October 2008 Archives

Readings soared into the 70s across the Chicago area Friday -- the region's warmest in
18 days and only the fifth 70-degree or higher temperature in October. A typical
October produces nearly twice as many.
O'Hare Airport's 70-degree high was the mildest Halloween reading here in eight years.
Even warmer readings were observed in other parts of the area. Northerly Island
reached 73 degrees while the WeatherBug sensor in Libertyville and New Lenox recorded
75 degrees. Highs of 73 degrees were reported at DeKalb and Plainfield. Warmest of all
was Burlington, Wis., where the mercury hit 79 degrees.
October 2008 closed 6.3 degrees cooler than its 2007 counterpart, but still managed to
be 0.6 of a degree warmer than normal.

RESURGING WARMTH PROMISES
NEAR-RECORD ELECTION DAY HIGHS
The passage of a cool front overnight has introduced northeast winds which slash
temperatures here by at least 14 degrees Saturday. But the front moves north of the
area Sunday afternoon, placing Chicago back in unseasonably mild air expected to last
through midweek. South winds and abundant sunshine could push Election Day
temperatures to near-record levels here.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
What month has had the most 6-inch or greater snowfalls here?
Nick Recchia, River Grove
Dear Nick,
Six-inch snowstorms: a child's delight and a motorist's nightmare. Chicago
has its share of such storms, to be sure, but, given its reputation as a
cold and snowy Midwestern city, not as many as one might suppose.
Chicago weather historian Frank Wachowski cracked open the record books to
provide the following snowy statistics. Based on 80 years of snowfall data
compiled at Midway Airport since 1928, the city has logged 112 snows of 6
inches or greater, an average of 1.4 per winter season.
Here's the monthly breakdown: November, 3 storms; December, 30; January, 25;
February, 26; March, 24; April, 4. Two surprises: April leads November; and
December, only the city's third-coldest month (behind January and February),
leads the pack.

Thanks for joining us for this Friday edition of Before the Forecast! Happy Halloween everyone! O'Hare airport hit 70 degrees today, and we can expect the mild weather will continue through the weekend. Electon day is the next chance we could see 70 degrees. Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Eric Szos for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

CHICAGO TUESDAY NOV. 4 ELECTION DAY WEATHER FORECAST
AND OBAMA RALLY WEATHER UPDATE
There has been no change in our Election Day weather forecast for Chicago. The area continues in line for the mildest Election Day weather which has occurred in Chicago in 44 years since Election Day (Nov. 3) 1964 when the city's official high was 75 degrees.

TUESDAY NOV. 4 ELECTION DAY FORECAST
Issued Friday Oct. 31
Mainly sunny, breezy and unseasonably warm. Temperatures 16 degrees above normal! Completely rain-free! South to southwest winds 11 to 23 m.p.h. with some gusts. (Normal Nov. 4 high: 54 degrees). Highs approaching 70 degrees.

OBAMA TUESDAY NIGHT INTO WEDNESDAY MORNING RALLY
Scheduled to run from 8 p.m. Tuesday evening to 1 a.m. Wednesday morning
Scattered clouds, breezy and unusually mild. Rain-free! Temperatures at the start of the rally near 64 degrees falling to 56 degrees by the rally's end.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Our friend Anson Mount turns the camera on himself for this photo. If you're a regular visitor to our blog, you recognize Anson's name from the many postings of his photos over the years.
We wanted you to have a chance to actually see him. Anson's a pilot, and here we see him at work in the pilot's seat. Check out Anson's shot of a temperature inversion on a flight from Waukegan to Watertown, Wis., taken Thursday. He tells us the inversion topped out around 2,500 feet -- an observation which matches vertical temperature "soundings" which were taken over the area yesterday. Happy Halloween Anson!
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Photo courtesy of Anson Mount, Waukegan, Illinois

Chicagoans basked in the first 60-degree temperatures in 11 days Thursday. The
mercury reached 62 at O'Hare International Airport just before 4 p.m. and 63 at Midway.
Even warmer readings were reported at Rockford (65 degrees), Joliet (66), St. Charles
(66), Marseilles (67), Morris (68), and Peru (70). Converging winds ahead of a
southbound late-day cold front Friday are likely to drive readings even higher on
Halloween with 70-degree temperatures a distinct possibility.

The warm-up dominates much of the country's Heartland. In Marquette, Mich., where 2
inches of snow fell Monday, high temperatures Thursday soared to 64 degrees -- a new
record and even warmer than Chicago's high. The dome of warm air produced 80s in
sections of the Plains just east of the Rockies including 82 degrees at Boulder, Colo.,
and 82 at Kearney, Neb.

FAIRBANKS, ALASKA TO CLOSE BOOKS ON 4TH COLDEST OCTOBER EVER

Bitterly cold air has gripped our 49th state over the past week. At Chandalar Lake,
Alaska, temperatures plunged to 42 degrees below zero. In Fairbanks, the books are
poised to close on the city's 4th coldest October.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
How does all the rain we had this summer compare to the rainiest places in the world?

Anna Spiczynski, Chicago

Dear Anna,
The world's wettest locations are on mountains or ridges situated so that prevailing
winds force moist oceanic air inland and upslope. In the United States, the wettest spot
is on Mt. Waialeale on the island of Kauai, Hawaii. The annual rainfall there is a
whopping 460.0 inches -- about 38 feet of rain -- or 12.7 times Chicago's annual
average of 36.27 inches.

With 43.28 inches of precipitation (rain plus the water content of melted snow) as of
October 25 at O'Hare, only an additional 6.08 inches is needed to establish a
new annual record (currently 49.35 inches registered in 1983).

The world's wettest location is Lloro, Colombia, with 523.6 inches (14.4
times Chicago's average). There, prevailing west winds carry in moist tropical air from
the Pacific Ocean.

Thanks for joining us for this Tuesday's edition of Before the Forecast! Despite less sun time Chicagoland is feeling a slight warm up. But will it last for election day? Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather interns Ellen Lytle and Aaron Brackett, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Thanks go out to Gina Tedesco from the Morton Arboretum who was kind enough to share
these pictures of this fall's spectacular display of color, which she describes as the "best
in a long time."

Photo courtesy: Gina Tedesco

Great weather expected for both Election Day and Obama Election Night Rally

Mildest Chicago Election Day in 44 years predicted next Tuesday—with the windy, rain-free and mild conditions extending through Tuesday evening/Wednesday morning’s Obama Rally at Grant Park

ELECTION DAY WEATHER FORECAST----For next Tuesday November 4, 2008

The evidence for warm, windy and rain-free weather for Election Day as well as for the Grant Park Obama Rally in the 8pm to 1 am period Tuesday night and Wednesday morning continues VERY strong. Showers and late-season thunderstorms are not likely reach Chicago until Wednesday night and Thursday next week---WELL after the election and rally.

Here’s our latest Tuesday November 4 weather forecast:

Chicago’s mildest Election Day in the 44 years since a 75-degree Chicago high on Election Day (November 3) 1964 . Generous if not unlimited sunshine next Tuesday Nov. 4, windy and unseasonably mild. Only a few fair weather clouds and patches of high thin clouds. South to southwest winds increase 12 to 24 m.p.h. Tuesday’s predicted high: 68-degrees. (Note: That’s 14-degrees above the normal 54-degree November 4 high and 19-degrees above the 49-degree high last presidential election day in Chicago in 2004.

FORECAST FOR THE OBAMA GRANT PARK RALLY Tuesday evening/early Wednesday morning

Fair, breezy and quite mild for the season from 8 pm-1am Tuesday evening into Wednesday morning. South winds 12 to 18 m.p.h. during the rally at Grant Park temperatures at 8pm around 62-degree lowering to 56-degrees by 1 am. That’s remarkably mild for a November evening which typically cools to lows in the mid 30s at night. Current indications are that showers and thunderstorms advancing through the Plains are NO THREAT to the Grant Park Rally Tuesday night/Wednesday morning, remaining WELL west of Illinois until Wednesday night.

Tom Skilling, Chief Meteorologist, WGN/Chicago Tribune

A mild late-autumn pattern is poised to take over from the chill of recent days. The
cold readings of late have slashed October's average temperature to 52.6 degreesa --
6.8 degrees cooler than the same period a year ago and 1.7 degrees below the 137-year
average. That places this month among the coolest third of Octobers on the books here
since 1871.

The U.S. was a country meteorologically divided on Wednesday between the record-
breaking morning chill that gripped Florida -- nearly all of the state's weather
observing stations recorded new lows -- and surging readings in the Plains. Down-
sloping winds compressed and warmed in the Dakotas sending afternoon highs to 78
degrees at Dickinson -- a record. The mild air is surging eastward and is behind the
warm-up predicted for Chicago. Highs in the 60s on Thursday and Friday mark the first
time in 11 days readings have broken above 60 degrees.

If Friday's high temperature matches the 69-degree prediction, it would make
Halloween 2008 the warmest since the 68 degree Halloween high in 2001.

ELECTION DAY (TUESDAY) COULD BE THE MILDEST HERE IN 44 YEARS

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
What date and year has Chicago recorded its earliest measurable snowfall?

John Lustrup

Dear John,

Chicagoans don't think of October as a "snow month," but in fact October brings the
first snow of the approaching winter season in more than half of the years. A computer
scan of the city's official snowfall data set reveals that the first snow of the season has
occurred by Oct. 31st in 65 of 124 years, or 52 percent of the time.

Oct. 12 stands as the date of Chicago's earliest-occurring measurable snow in the
autumn: 0.3 of an inch fell on that date in 2006. However, Chicago weather historian
Frank Wachowski tells us that measurable snow has fallen even earlier in the season at
Midway Airport when 0.2 of an inch fell on Oct. 8, 2000, but Midway was not the official
observation site at that time (by then, O'Hare International Airport was, and still is, the
official site).

Thanks for joining us for this Wednesday edition of Before the Forecast! After a pleasant day with generous amounts of sunshine, we can expect to see the same weather for the next couple of days. Temperatures could possibly hit 70 degrees by Friday. Tom Skilling explains it all on Tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Predicted weather for Election Day and the Obama Grant Park rally Tuesday night

Chicago’s mildest Election Day in 44 years is predicted Tuesday. Partly sunny, windy and mild weather. A high of 68-degrees—the mildest Election Day temperature since the 75-degree high here on Election Day (November 3) in 1964.

Clouds increase Tuesday evening and night, gusty south/southwest winds and mild temperatures. Current indications—subject to update---are that showers advancing through Iowa Tuesday night may wait until after the rally to reach Grant Park. The progress of those showers will have to be monitored and we will update this forecast regularly in coming days.
Tom Skilling Chief Meteorologist WGN Weather Center

The powerful early season cold blast in recent days responsible for Chicago's chilliest
weather in 6 months, and freezing temperatures south to Florida, produced explosive
storm development on the Mid-Atlantic coast Tuesday. Barometric pressure readings
-- a gauge of storm intensity -- went into a 12-hour dive which revved coastal winds
to gale force (39+ m.p.h.) while burying northern New Jersey, eastern Pennsylvania and
a swath of eastern New York beneath one of the region's heaviest early season
snowfalls. National Weather Service forecasters ranked the 17 inches that fell in
northeast Pennsylvania as that area's heaviest early season accumulation in at least
three decades while the 14 inches measured at High Point State Park, N.J., was that
state's heaviest early snowfall on record. New York fared little better. New Kingston was
buried beneath 15 inches. Winds drove rain horizontally in Cape May, N.J., and roared at
velocities up to 66 m.p.h.

By contrast, temperatures in the Plains soared 25 degrees Tuesday afternoon over
readings 24 hours earlier. The eastbound mild air promised relief from the chill in the
Midwest.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
My husband likes to say that it "always rains on Halloween." I know that is not true, but
how many times has it rained on Halloween in the past 50 years?
E. Howard

Dear E. Howard,

Your husband is exaggerating, but there have been quite a few rainy Halloweens in the
last half century. Chicago climatologist Frank Wachowski noted that since 1958 at
least some rain (trace of more) had fallen on 27 of the past 50 Halloweens(54 percent).
The last two Halloweens here have been dry, but most recently rain fell 2005 and in
2003. In 1994 the city experienced its rainiest Halloween on record when 2.26 inches of
wind-driven rain soaked the area. Before midnight some western suburbs even reported
some snow. That rainstorm produced tragic consequences when 68 people perished in
a plane crash near Roselawn, Ind., a result of severe icing.

Thanks for joining us for this Tuesday edition of Before the Forecast! Big snows are occuring in eastern portions of the country as chilly polar air inundates the area. For the Chicago area, a warmup is expected just in time for trick or treating. Tom Skilling explains it all on Tonight's BTF. A big thank you goes out to our weather intern Aaron Brackett, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Kurt Neumaier reports large, heavy snowflakes fell for nearly 20 minutes and stuck to
everything in Saint John, Indiana. It was the area’s first snow. What great
photos---thanks Kurt!

Photos courtesy of Kurt Neumaier, Saint John, Indiana

We often show you Weather Bug video of weather conditions in Algonquin as observed
from Ericson Marina. Anson Mount, a frequent photo contributor to this blog, snapped and
submitted this shot of the Marina which sits on the Fox River there. Tuesday's wispy
cirrostratus---which take on the appearance of mares' tails---hover above. Thanks
Anson!

Tom Skilling

Photo courtesy of Anson Mount, Algonquin

The coldest temperatures in nearly seven months will have Chicagoans shivering as
Tuesday gets under way. The mercury dropped into the 20s at O'Hare and over many
areas away from Lake Michigan overnight. It's the first time since the 28-degree
minimum on April 2 that the city's official low temperature dipped below 30 degrees.
The chill, which prompted frost and freeze advisories across sections of 17 states
overnight, is part of a massive early season cold air incursion that sent temperatures
plummeting into the 30s south to north Florida and the Gulf Coast.

Lake-effect rain and snow showers have targeted northwest Indiana and lower
Michigan. Snow covered the ground in the northern Midwest, with accumulations of 3
inches at Eagle River, Wis, and 2.2 inches at Marquette, Mich.

2008 GROWING SEASON ENDS 3 DAYS SHORTER THAN NORMAL

With sub-freezing temps overnight, the 2008 growing season has come to an end. The
growing season is the period between the last frost of spring and the first frost of fall.
Normally 183 days in length, this year it was 180 days.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,

My great-grandchildren are old enough to trick-or-treat now and I've been telling them
about some very warm Chicago Halloweens that I remember back in the 1930s. Can you
refresh my memories so I give them more detail?

Clara Price

Dear Clara,

You must be recalling the Halloweens in 1933 and 1935 when the temperature peaked
at a summery 78 degrees. In fact, since 1871 only two Chicago Halloweens have been
warmer, 1950 when it reached 84 degrees and 1944 when the mercury hit 79. Not only
was Halloween 1933 warm but it was also dry, a great day for trick-or-treating, but in
1935 a steady rain fell after 8 p.m. putting a damper on the festivities. The city's last
truly mild Halloween was back in 2000 with a high of 70 degrees. In contrast, the
coldest took place in 1873 when the high was only 31 and the low 23 with some light
snow reported at times.

When snow melts and refreezes again while falling, it takes on an almost
kernel-like appearance. Such snow is referred to as graupel snow,
pictured here. These photos come to us from Chuck Heaver who shot them
in Union Pier, Michigan. The lake-effect set up behind Monday night's
rain and snow showers is occurring from roughly Porter County, Indiana
east. The warm 54-degree lake waters are responsible for imparting some
warmth to the atmosphere there which is melting the snowflakes falling
from cold clouds aloft. This refreezing of the partially melted
snowflakes is producing the graupel which Chuck's photos show
accumulating on the still warm ground in the Michigan lake snow belt.

Tom Skilling

Photos courtesy of Chuck Heaver, Union Pier, Michigan

Tyler Christiansen e-mails this shot of Sunday's precipitation producing towering
cumulus and asks if they are some sort of snow squall or snow rollers. What you're
seeing Tyler is swath of falling snow which would, given the powerful winds in play
Sunday, come closest to a snow squall. Great shot—thanks Tyler.

Tom Skilling

Photos courtesy of Tyler Christiansen

Sunday's powerhouse cold front was accompanied by eye-catching cloud formations
many of you have been good enough to send us. Ross and Amy Jones snapped these
shots around 4 p.m. in Plainfield, Illinois of towering cumulus clouds from which a wispy
region of falling snow is evident--what might be called a "snow shaft". Temperatures
were very cold just above the ground supporting the swath of falling snow which is
evident in these terrific shots. Thanks Ross and Amy!

Photos courtesy of Ross and Amy Jones, Plainfield, Illinois

Thanks for joining us for this Monday edition of Before the Forecast! Today we failed to reach the 50 degree mark, and tomorrow could have the same fate. Temperatures are, however, expected to rebound later this week. Tom Skilling has all the details on tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Check these marvelous shots taken near Michigan City High School of mammatus
clouds which appear to hang from the underside of an anvil-shaped towering cumulus
clouds. Tama Pickford was good enough to send these along and asks in her
accompanying e-mail is these are "upside down" clouds. It certainly looks that way,
doesn't it? Mammatus clouds DO have the appearance of hanging from a cloud deck
above so Tama's description is a good one. This formation occurred as a powerful cold
front roared across the area--a development which sent temperatures tumbling and
produced the first official flakes of snow at both Midway and O'Hare in Chicago Sunday
afternoon and evening. Thanks Tama for the great shots!

Tom Skilling

Photos courtesy of Tama Pickford, Chesterton, Ind.

Many thanks to Chuck Hagen of Oak Lawn for sharing these beautiful fall photos taken Sunday at Starved Rock State Park at Utica!

Tom Skilling

Photos courtesy of Chuck Hagen, Oak Lawn, Illinois

Chicagoans got a sneak preview of upcoming winter Sunday afternoon as strong
west-northwest winds swept remaining leaves off trees and brought a late-autumn
chill into the area. Early afternoon readings that peaked in the middle and upper 50s
had dropped into the 30s by evening after an afternoon that featured rain, snow
showers and some small hail. Highest wind gusts were clocked at 61 m.p.h. at West
Chicago, Gary and the Harrison-Dever Crib. Sunday's winds produced scattered tree
damage and power outages throughout the city and suburbs.
Several locations reported snow pellets Sunday afternoon including the official O'Hare
site, marking the start of the 2008-09 snow season five days ahead of schedule.

FREEZE TO END GROWING SEASON; SHARP WARM-UP TO FOLLOW
Frosts have occurred in scattered inland areas already this fall, but this vigorous cold
snap should bring widespread subfreezing temperatures to many inland areas this
morning and to much of the region tonight with the possible exception of the
immediate lakeshore. Southwest winds return by Wednesday, sending the mercury back
to the 60s by Thursday and Halloween.
--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
I am negotiating a snow removal contract for our homeowner's association.
How many snows of two inches or more does the Chicago area receive in a
typical winter?
Joseph Hudetz
Dear Joseph,
Chicago's snow records date back 124 seasons to the winter of 1884-85, and
the long-term averages show that the city receives measurable snowfall (0.1
inch or more) on 29 days each cold season and a snowfall of 2 inches or more
on six occasions. Of course, those numbers can vary tremendously depending
upon the nature of the winter. The city has never gone through a winter
without a 2-inch or greater snowfall but on two occasions, first in the
winter of 1921-22 and again in 1936-37, there was only one such event.
Compare that to the 15 2-inch-plus snowfall events during the snowy winter
of 1977-78, and you get an idea of the winter-to-winter variability in
snowfalls that Chicago has experienced.

West winds will howl across the Chicago area Sunday, a harbinger of the season’s first
cold-air blast that will send the mercury tumbling to its lowest levels since April.
Though readings peak in the middle 50s on Sunday, west winds will gust as high as 50
m.p.h. as the colder air arrives. Skies will cloud over by evening as temperatures fall
through the 40s and into the lower 30s by Monday morning, which could bring not only
the season’s first freezing temperatures but the first snow flurries as well. The
combination of gusty northwest winds and high temperatures struggling to reach only
the lower 40s Monday will give the day an early-December feel. The chill will be
fleeting, as readings rebound to the middle and upper 50s midweek, setting the stage
for a mild Halloween with temperatures surging into the 60s.

MIDWEST’S FIRST WINTER STORM WATCHES IN WISCONSIN, MICHIGAN

The system responsible for Chicago’s chill will bring lake-effect snowfall to portions of
the upper Midwest downwind of Lake Superior. Winter storm watches have been posted
for up to 8 inches of snow from Bay- field, Wis., to just south of Upper Michigan’s
Keweenaw Peninsula by Monday.

Dear Tom,

How come we never hear of any hurricanes hitting the U.S. Pacific Coast?
Frances Lang, Glen Ellyn

Dear Frances,

Water off the coast is too cold. Eastern Pacific hurricanes usually develop from Baja,
Mexico, south to Central America, where the ocean water exceeds the 80-degree-plus
warmth needed for storm formation. Water temperatures plummet quickly northward
along the California coast, dropping into the 60s—a value prohibitively cool for
hurricanes. Farther north off Oregon and Washington, the water temperature is in the 50s.
On rare occasions, a Pacific hurricane will move north, hugging either side of the Baja
Peninsula and affect the southwestern United States. In September 1939, one of these
storms, known as El Cordonazo, brought gales and heavy rain to Los Angeles and San
Diego.

Lightning flashed late Friday from low-topped thunderstorms across the Chicago area.
The storms bubbled into existence as a pool of unseasonably cold air at the heart of a
slow-moving storm system aloft swept directly overhead. It's a development which
encouraged 54-degree air at ground level to ascend into subfreezing air hovering less
than a mile above the surface and fostered hailstone formation. Quarter- to
half-inch-diameter hail was reported at Sugar Grove, Pecatonica, Elburn, Plano and
Flossmoor, as well as Munster and Crown Point in Indiana. The rainfall spawned by the
storm had pushed Midway Airport's two-day tally to 0.65 inches by late Friday. Heavier
rain totals occurred to the west where 1.01 inches fell at Pontiac, 0.92 inches at Morris
and 0.87 inches at Marseilles.
A classic high-wind scenario threatens to take shape Sunday as west-northwest surface
and jet stream winds align.
Subsidence as arctic air approaches could mix 40-50 m.p.h. gusts down to the surface --
inducing compressional warming which initially delays the onset of the coldest air but is
still likely to whisk the coldest air in six months into the area Sunday night and Monday.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Your recent column regarding ragweed prompts me to write. When I was a
child, ragweed (also known as goldenrod) was considered extremely
detrimental to those with allergies and asthma, but nowadays this is not the
case. Why does no one connect this deadly ragweed to the terrible increase
in asthma cases?
Grace Hansen, Des Plaines
Dear Grace,
Goldenrod and ragweed are entirely different plants. The Great Plains Nature
Center in Wichita, Kan., says, "Goldenrod gets mistakenly blamed for the
agonies of hay fever sufferers in autumn. It blooms at the same time as
ragweeds, which are the real culprit. Ragweeds are pollinated by the wind."
Goldenrod pollen is fat and sticky, and carried by insects. It is not borne
on the wind like ragweed pollen. The Center explains, "People suffering from
allergies ... look for a flower to blame and goldenrod gets the rap because
it is so visible and abundant."

Tracey Surface of Chicago shared with us some amazing lightning photos Friday night,
including the one shown below. Thanks Tracey!
--WGN-TV Weather Center

Photo courtesty of Tracey Surface, Chicago

Thank you for joining us for this Friday edition of Before the Forecast! Showers and a few embedded thunderstorms have invaded the area. Get ready for back-to-back 40 degree temperatures since late April. Tom Skilling has all the details on tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Quarter- to half-inch-sized hail was reported at several locations Friday afternoon as
rain clouds overspread the Chicagoland region. Locations reporting hail included
Elburn, Sugar Grove, Crown Point, Munster, Flossmoor, Lake Zurich and Plano. Matthew
Cumberland was kind enough to share these photos of the hail that fell in Plano. Also
added is a photo from Greg Huggins in Sugar Grove. Thanks Matthew and Greg!
--WGN-TV Weather Center

Photos courtesy of Matthew Cumberland, Plano, Ill.

Photo courtesy of Greg Huggins

Mike Frankowski was kind enough to share this wonderful fall photo with us. Mike took
the picture today (Oct. 24, 2008) along the Illinois Prairie Path in Wayne, Ill. Thanks Mike!
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Photo courtesy of Mike Frankowski, South Elgin

Maxine Levy of Arlington Heights was kind enough to share these wonderful pictures with
us. Thanks Maxine!
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Photos courtesy of Maxine Levy, Arlington Heights, Illinois

The powerful easterly winds that tapped dry air for a time and held rain at bay much of
Thursday finally eased and yielded to rain late in the day. The winds were behind
6-foot-high waves that pounded the Illinois shoreline for a time. But as velocities fell,
the atmosphere became saturated with moisture and the heavens opened. Rains that had
drenched areas of Illinois west and south of Chicago much of the day began falling in the
western suburbs from Aurora and Joliet around 4 p.m. and began falling in the city around
6 p.m. Downstate rainfall totals included 1.10 inches at Marion, 1.09 inches at Effingham
and 1.01 inches at Decatur. Nearly 0.70 inches fell in St. Louis.
TEMPS PLUNGE LATE SUNDAY AS ARCTIC FRONT HITS WITH 30 M.P.H.-PLUS WINDS
Big changes loom early next week as a strong cold front passes through the city Sunday
afternoon, sending readings plummeting from highs near 60 degrees midday to the
lower 30s by Monday morning, bringing not only light showers or sprinkles but
possibly the season's first snow flurries. Highs on Monday will struggle to reach the
lower 40s, a level more typical of late November or early December.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Why do typhoons and hurricanes have different names since the only
difference between them is location?
Pamela, Tinley Park
Dear Pamela,
Tropical cyclones are a global phenomenon developing in tropical waters both
north and south of the equator. The storms are given regionally specific
names including hurricane in the Atlantic, Caribbean, and northeast Pacific,
and typhoon in the northwest Pacific. These names have developed over time
primarily from the cultures located in the areas that they affect. The word
hurricane is thought to be derived from the word huracan, a Taino and Carib
god, or hunraken, the Mayan storm god. The word typhoon seems to have
originated either from the Cantonese t'ai fung (a great wind), the Arabic
tufan (smoke) or from the Greek typhon (a monster). In the Indian Ocean,
these storms are referred to only as severe cyclonic storms or tropical
cyclones.

Jim Bayne sends us such fascinating photos -- and these images are no exception!
Jim e-mailed to say:

"I went out on a boat this morning and happily rode the waves as I captured the attached
shots . . . a bit rough and windy as I enjoyed the HIGH temps of this week (or so) . . . the
boating season lives on for yet another day!"

It does indeed, Jim! THANKS as always for sharing these shots with us!

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Photos courtesy of Jim Bayne, Chicago

Thanks for joining us for this Thursday edition of Before the Forecast! A cut off low in the Midwest is slowly moving towards the Chicagoland area bringing some rain showers. How long will this last? Tom Skilling has all the details on tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Gusty east to southeast winds, which took hold Wednesday afternoon, continue
Thursday. They're part of the circulation of a powerful autumn storm that has drenched
the Plains and western Midwest in recent days. Rainfall exceeded 3 inches there
Wednesday as powerful 55+ m.p.h. gusts raked an area from South Dakota to Kansas.
The wind, in combination with a 2-inch coating of wet snow, downed trees in O'Neill,
Neb., while 4.16 inches of rain doused Beaver City in south-central Nebraska. A
blizzard warning was issued for northwest Kansas and motorists were warned that 50
m.p.h. winds and heavy snow threatened to slash visibilities to a quarter-mile or less
with local white-out conditions into Thursday.

The storm, cut off from a powerful jet stream steering winds to the north, is only
expected to crawl across the Midwest, delaying rain's arrival in Chicago until early
Friday. Once here, rainfall could reach a half inch or more.

SEASON'S COLDEST CHILL YET BOOSTS LATE WEEKEND FLURRY
POTENTIAL

Early-season arctic air brings back-to-back 40s Sunday and Monday. Sprinkles could
mix with some flurries.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Could you please explain what a front is? It is a very strange sounding term.
Mrs. Mary Toth

Dear Mary,
Like all areas of inquiry, meteorology has its own language of technical terms, many of
which undoubtedly sound strange to an unaccustomed ear. In the atmospheric
sciences, a front is the transition zone or boundary between two air masses of
significantly different characteristics.

Fronts are often a few hundred miles in length, sometimes over a thousand. In width, a
frontal boundary zone ranges from a few miles to about 50 miles. Air temperature and
moisture are two of the characteristics that cause air masses to differ, and in the usual
case one air mass is colder and drier than the other. A front can be stationary, but it
usually moves (though rarely faster than 40 m.p.h.). When colder air is advancing, it is
called a cold front; with warmer air advancing, a warm front.

Thanks for joining us for this Wednesday edition of Before the Forecast! Today we hit the coolest temperature since early May at 52 degrees. Tom explains the cooler temperatures in store for the coming weekend. All this and more on tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Mark Vogan, who as a resident Scotland, is so wonderful at keeping us posted on
weather developments on the UK, e-mails these photos taken Tuesday. They depict the
effects of high winds on Scotland's north coast and offer stunning examples of rain
shafts associated with incoming squalls. Snowcapped mountains can be seen in Mark's
photos. Mark describes one stop on his 600 mile trip to Scotland's north coast
Tuesday:

"When parking the car and looking over the stone that said, DUNNET HEAD, BRITAIN'S
MOST NORTHERLY POINT, WELCOME.. The wind was rocking the car, at times violently. I
stepped out and thought I was in a hurricane as the winds were fierce like I had never
felt before. The cliffs are as dramatic as the huge swells that rolled into the Scottish
coast. I believe winds were sustained at 50 mph in 20 to 30 sec intervals with gusts on
top in the 70 to 80 mph range, though I have emailed the METOFFICE to see if they have
measurements that can verify this for me."

Thanks for keeping us posted on the weather in your part of the world, Mark! Your
photos are magnificent!

Tom Skilling

Photos courtesy of Mark Vogan, Glasgow, Scotland

They deal with tornadoes, blizzards, and floods, but Chicago meteorologists also know how to have fun.

Watch Chicago's weather men and women -- including our very own Tom Skilling -- in a music video produced for the 50th Anniversary of the Chicago Emmy Awards, October 18, 2008.

Wednesday dawned with frost in a number of western suburbs for a second consecutive
morning. The overnight chill followed Tuesday's 55-degree high -- a reading in stark
contrast to the 80 degrees recorded a year earlier. Tuesday's chilly high tied for fall
2008's coolest.

To date, October is running a modest 1.3-degree surplus. But the month's average
temperature is well behind a year ago. While Chicagoans have been treated to one
80-degree day earlier this month, eight had occurred in October 2007.

A storm taking shape in the Plains is eastbound and likely to bring wetter weather
toward Friday. Eight of the 13 most recent computer models suggest rains of a half
inch or more will fall across the Chicago area with the late-week storm.

FALL HARVEST WELL UNDER WAY -- 2 WEEKS OF GOOD WEATHER NEEDED

Will County farmer John Hazzard reports that 95 percent of soybeans and 35 percent of
the corn in his area have been harvested -- ahead of the statewide average reported
earlier this week by USDA. Area farmers would like to see another two weeks of good
weather to finish their fieldwork, but may have to contend with late-week rain.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
I have some old family photos labeled "the farm after tornado March 25, 1942". The
farm was near Fairview in Fulton County, Illinois west of Peoria. Do you have any
information on this storm?
Bev Cherney

Dear Bev,

The picture may have been taken on March 25, 1942 but the tornado actually occurred
nine days earlier on March 16.

Several twisters struck central Illinois that day, an F4 storm that killed 11 northeast of
Champaign near Alvin, an F2 that hit near Yates City northwest of Peoria and the F2
tornado that struck your family farm. This tornado moved northeast on a 10-mile path
through Fulton County. The twister struck 13 farms causing damage estimated at about
$100,000. Many homes were torn apart and barns were destroyed. Eleven
people were injured in the storm but fortunately there were no fatalities.

Thanks for joining us for this Tuesday's edition of Before the Forecast! Today's high temperature tied with yesterday's as the coolest yet of the season! Tom explains the cooler temperatures and even mentions snowfall as a possibility in the next few weeks! All this and more on tonight's BTF. A big thank you goes out to our weather intern Ellen Lytle, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

This is truly eye-catching! Luis Tamayo, a photographer originally from
Northbrook and now living in Virginia with his wide who is stationed
there and is an officer in the U.S. Navy, shares this remarkable photo
of a cloud with an uncanny similarity to an Eagle. Luis explains how
this photo came to be:

" We had taken a few days to do some sight seeing in western Virginia
with my in-laws who where visiting from Japan. Just before we where
about to check-out of the hotel, my father in-law called me to the balcony,
I was amazed at what I saw. He ran to the car to get the digital camera,
I pulled out my Nokia cellular phone and took the picture you see. By the
time he returned with the camera, the eagle's beak was dissipating."

It's an amazing shot! Thanks for sharing it with us Luis!

Tom Skilling

Photo courtesy of Luis G. Tamayo, Suffolk, Virginia

Check out fog rolling off Amanda Pickett’s pond in Winfield, Indiana Tuesday morning.
Amanda includes some other photos, including a picture of her kittens Pixie and Shelley
who were out enjoying all the beauty of an autumn day in northwest Indiana! Thanks
Amanda!

Tom Skilling

Photos courtesy of Amanda Pickett, Winfield, Indiana

Gorgeous rainbow shot over Lake Michigan taken by Kim Piotrowski looking out her office
window Tuesday. Thanks Kim for the great shot!

Colden M. Searles shares this amazing photo of the rainbow produced near Chicago’s
lakefront by lake-effect rain showers which swept ashore over Tuesday’s lunch hour.
What a fantastic shot! Thanks Colden!!

Tom Skilling

Photo courtesy of Colden M. Searles, Chicago

The lake-effect rain machine will be active Tuesday, particularly in the morning. Not
only have the chilly north winds that greet Chicago morning commuters traveled the
length of Lake Michigan, the atmospheric setup also features a temperature decline
between the lake surface and a mile aloft of 30-degrees. That's a much steeper drop
than normal. A decrease of just 20 degrees is enough to encourage air to rise and cool
producing lake clouds -- so Tuesday's elevated decrease goes even further in
encouraging the comparatively mild air hugging the lake surface to ascend and cool --
a prerequisite for cloud and shower formation.

The lake setup breaks down Tuesday afternoon and chilly temperatures Tuesday night
threaten frost away from the lake. Monday's 55-degree high is the chilliest of the fall
season to date. It's also the coolest since May 28.

ATMOSPHERIC STIRRINGS OVER GREENLAND AND NORTH ATLANTIC SIGNAL
NEW CHILL HERE NEXT WEEK

Buckling of jet stream is to set up northwest flow aloft over the Midwest.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,

I live on the ninth floor of a 14-story condo near Lake Michigan. What should I do in
the event of a tornado?

Sally J. Loeser, Chicago

Dear Sally,
The structural strength of skyscrapers, and even medium-rise structures such as yours,
far exceeds the stresses that tornadic winds could apply to them. Winds in excess of
100 m.p.h., sometimes much higher, occasionally buffet the upper reaches of Chicago's
higher downtown buildings in the winter, and channeling of winds between high-rise
buildings sometimes creates those extreme winds at lower levels as well.

Be advised, however, that windows will shatter and exterior walls may tear away. For
those reasons, the safest and most tornado-proof location in a condominium high-rise
or office skyscraper is an interior closet or an interior stairwell. Do not try to get to a
lower floor and do not use the building's elevators.

Monday started with such promise. Our friend pilot Anson Mount was flying over Lake
Michigan before clouds thicken and the rains arrived and shares this shot with us. Thanks
Anson!

Tom Skilling

Photo courtesy of Anson Mount, Algonquin, Illinois

Get ready for more autumn like temperatures as we will struggle to reach the 60 degree mark for the rest of the week. Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Our thanks to Tom Janito for this great shot of Sunday's (10/19/2008)
altocumulus clouds over the Fox River in Oswego! This is beautiful.
THANKS Tom!

Tom Skilling

Photo courtesy: Tom Janito

Rain showers are often involved in the production of rainbows—especially when the sun in
low in the sky----i.e. either rising or setting. Such was the case this past Saturday
morning (October 18) when Paul Lanzo snapped this remarkable photo in Melrose Park.
Paul has been kind enough to share hit incredible shot with us. THANKS Paul!

Tom Skilling


Photo courtesy: Paul Lanzo

Paul Havlik, armed with his Canon Rebel XT, shares these awesome shots of Greenland
taken while flying at 35,000 ft and over 500 m.p.h. this past Friday afternoon (October 17)
as he returned by air from an overseas business trip. The flight from Paris arced north
over Greenland--not unusual route for flights headed for the U.S. from Europe as pilots
attempt to fly north of mid-latitude jet streams thus avoiding powerful. Flight-slowing
headwinds. Paul explains the two photos in his e-mail, telling us:

“The two pictures (I have dozens) that I selected are:

1. Image of the eastern side of Greenland where you can see the creation of hundreds
of ice bergs. The mountains really hold back the sheet behind them, but the the
glaciers feed down the sides to the ocean.

2. This second image is of a glacial valley on the southwest coast. You can clearly see
the icebergs from the calving and how the glacier has retreated up the valley. “

With Greenland so often mentioned in discussions of climate change, it’s interesting
to have a first hand view of the ice which covers so much of the land mass there. MANY
THANKS to Pauil Havlik for sharing these photos with us! They are something to see!

Tom Skilling

Photos courtesy of Paul Havlik, Mundelein, Illinois

Just a week ago Sunday, the city basked in bright sunshine and record-tying mid-80
degree warmth -- but after readings struggle to reach 60 degrees Monday, the mercury
will be hard-pressed to get out of the 50s the rest of the week.
Slow-moving low pressure is forecast to develop, bringing the Midwest several cloudy,
damp and rainy days. Late-October 70 degree-plus warmth is not uncommon in
Chicago, having occurred in seven of the past 10 years -- but current outlooks
preclude any such rebound through the end of the month.
In addition to the inevitable late-autumn cool-down, the city is also approaching its
cloudiest time of the year. November and December average just 40 and 39 percent of
possible sunshine respectively, a large drop from October's 58 percent. This week's
dominant cloud cover should provide a preview of the upcoming dreariness.

ATLANTIC HURRICANE ACTIVITY
QUIETING DOWN AFTER A BUSY SEASON
The Atlantic Basin is currently storm-free after Hurricane Omar's recent demise, though
about six weeks still remain in the 2008 season which ends Nov. 30.
--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
How long does it take for total darkness to set in after sunset?
Does the length of time vary by season?
Tina Bohlen
Dear Tina,
Astronomer Dan Joyce tells us that most widely recognized definitions
for darkness are civil, nautical and astronomical twilight which occur
when the sun sinks six, 12 and 18 degrees below the horizon
respectively. Once astronomical twilight ends, astronomers are assured
that no extraneous light will appear on their telescopic images. In
rural areas, most people will stop noticing atmospheric illumination
shortly after nautical twilight ends, but city dwellers will not perceive
much difference beyond the end of civil twilight. There are small
variances during the year but in general the time from sunset to the end
of civil twilight is about 30 minutes with another 30 minutes for
nautical twilight and an additional 25 minutes for astronomical
twilight.

Strengthening southerly winds and abundant sunshine should allow temps to warm into
the mid-to-upper 60s Sunday afternoon. As a cold front approaches from the
northwest, clouds will spread across northern Illinois Sunday night acting as a blanket
to keep overnight temperatures mostly in the 50s. The cold front should move through
northeast Illinois Monday afternoon, preceded and accompanied by scattered brief
showers. Winds will shift to the north, and cooler air on the leading edge of a Canadian
high pressure air mass will feed into the metro area holding over the Midwest through
Wednesday.

LOW PRESSURE FORMS IN THE PLAINS

By midweek, a pocket of very cold air aloft is forecast to sweep out of western Canada
into the central Plains, creating a “cut-off low pressure system”. This slow-moving
system develops a broad area of cloudiness and showers. Showers may be mixed with
wet snow on the backside of this storm system. As the eastward-moving low center
approaches Kansas City, Mo. later Wednesday, the leading edge of the expansive cloud
pattern will spread over Chicago. Rain will begin here Thursday and persist into next
weekend.

Dear Tom,

Has Chicago ever recorded a temperature of 90 degrees or higher in the fall after a
sub-40 degree low?

Brandon D. Lade

Dear Brandon,

It hasn’t happened often, but we can find at least three such occurrences including one
just last year. On Sept. 15, 2007, Chicago set a record low of 39 degrees. Just nine days
later, on Sept. 24, warmth returned, and the city officially logged a high of 90. Similar
occurrences were noted in 1956 when after a 38-degree low on Sept. 20, the mercury
soared to 92 degrees just two days later on Sept. 22; and in 1951 when a 38 on Sept. 28
was followed by a 90-degree high on Oct. 4. Though 90s after 30s are rather
uncommon in Chicago, early season chills are often followed by warm-ups in the 70s
and 80s as northerly winds in the buckled jet stream that brought the chill move east,
putting Chicago in a warm southerly return flow.

A 57-degree reading recorded at 10:59 a.m. Friday proved all the atmosphere here could
muster. It was the second consecutive day readings failed to reach 60 degrees -- the first
time that's happened in nearly five months. Rain falling into a dry layer of air and
evaporating Friday afternoon -- a process meteorologists refer to as "evaporative cooling"
-- sent temperatures falling to late-November levels. By mid-afternoon, readings had
retreated to the mid-40s in Wheaton, Naperville, Darien and Frankfort -- easily the
coolest since May 27. Friday's chill followed a night of 30s in many suburban areas --
with cool air responsible for frost at some locations. Clouds eventually break Saturday --
but Sunday appears to be this weekend's real winner as gusty south winds bring a
temperature surge to Chicago. Though a far cry from last Sunday's record 84 degrees at
O'Hare Airport, Sunday's 70-degree high will be a 12-degree improvement over Saturday's
58. A system taking shape later next week threatens wetter weather. And at least four
punches of cool air are possible in October's remaining days. Despite recent chills,
October to date here is more than 2 degrees above normal -- but is running 4.8 degrees
behind a year ago.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Has a World Series game ever been snowed out?
Ed Berling, Lockport
Dear Ed,
Snow has fallen during at least three World Series games since the inaugural
Fall Classic in 1903, but no game has ever been snowed out. Prior to
baseball's expanded season and playoff structure, the World Series used to
be held in early October, so a major snowfall was never a concern. But now
with the final games potentially extending into November, the odds of a
postponement due to snow increase, particularly in the northern cities.
Ironically, two games that were played in snow flurries took place here in
Chicago during the 1906 World Series between the Cubs and White Sox on Oct.
9 and 11, 1906. More recently, snow showers fell during the late afternoon
on a very cold Oct. 22, 1997, in Cleveland during Game 4 between the Indians
and the Florida Marlins.

Some warmer air is coming in this weekend. Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Chuck Hagen of Oak Lawn shares with us some beautiful fall photos from Waterfall Glen
in southeastern DuPage County. Thanks so much Chuck, and on a personal note, we wish
you the very best this weekend!
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Photos courtesy of Chuck Hagen, Oak Lawn

Temperatures struggled to 59 degrees Thursday at the three major Chicago weather
reporting locations -- O'Hare and Midway Airports and Northerly Island. It marked only
the second time this autumn the mercury has failed to reach or exceed 60 degrees, the
fewest sub-60-degree highs to occur this far into the fall season since 1966 when only
one high had remained below 60 degrees. The chill continues Friday with a second day
of 50s predicted -- the first time back-to-back 50s have occurred here in nearly 5
months.

Some lake-effect clouds greet Chicago as Friday dawns. Temperatures drop 27 degrees
in the first mile of the atmosphere -- supportive of lake cloud development. The steep
vertical temperature decline encourages air to rise from the lake surface, cool and
condense producing clouds. But with an easterly flow in place, winds travel over 80
miles of the lake, allowing little time for significant moisture to evaporate and fall as
rain.

60 OF PAST 80 YEARS HAVE PRODUCED MULTIPLE 70s BEYOND OCT. 17

A 70-degree high is predicted Sunday. Weather records indicate an average of four
70-degree days occurred beyond this date.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,

During many of the thunderstorms in Chicago this past summer, strong winds often
started up a few minutes before the rain began. Were any of those winds associated
with tornadoes?

Thad Courter

Dear Thad,

The winds that you have described are called thunderstorm outflow winds, and they are
not associated with tornadoes. Raindrops falling from a thunderstorm literally drag
down with them the air through which they are falling. Much more importantly,
raindrops also evaporate as they fall, cooling the air they pass through and making it
heavier. A current of strongly descending air thus develops in the rain area of the
storm. When that current strikes the ground, it rushes out ahead of the storm,
producing the strong (and sometimes damaging), gusty, cooling winds that typically
occur at the onset of a thunderstorm.

Frost is possible for our friends to the west tonight as skies clear out over the area. Also, clouds have plagued northern Indiana and parts of Chicago as strong northerly winds blow over the lake. What does all of this mean for the days to come? Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather interns Aaron Brackett and Ellen Lytle, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Autumn's chill is in the air. Not since back-to-back daytime 50s occurred here nearly
five months ago on May 22 and 23 -- 59-degrees and 57-degrees respectively -- has
cooler air dominated Chicago's weather scene. Temperatures within a mile of the earth's
surface are so cool, they are to encourage north to northeast winds, predicted to blow
the length of Lake Michigan into the area to tap some lake moisture. It's a development
which could yield some lake-effect sprinkles Thursday night into Friday. Cooling aloft
and an upper disturbance predicted to pass Friday afternoon and night could ignite a
few light showers elsewhere across the metro area.

Six states -- from Minnesota across Iowa, Missouri and eastern Nebraska -- were
under frost and freeze advisories overnight. Breaks in the clouds and lighter winds may
permit 30-degree temperatures and patchy frost in Chicago's far western suburbs.

A low of 3 degrees below zero in snow-covered Fairbanks, Alaska, early Tuesday
marked interior Alaska's earliest sub-zero low since 1988.

OMAR THE STRONGEST LATE SEASON HURRICANE TO HIT THE VIRGIN
ISLANDS IN A DECADE

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,

When was the last time there was measurable snow here in November?
Linda Coleman

Dear Linda,

There was measurable snow here last year when a total of 0.3 of an inch fell on Nov.
21 and 22 and also in 2006 when 0.4 of an inch fell on Nov. 30.

In fact, the city's last November without measurable snowfall was in 2001. Since the
city's snowfall climatology began in 1884, measurable snowfall (0.1 of an inch or more)
has been logged in 101 out 123 Novembers (81 percent). While the snowfall in most
Novembers is light, the city has had some exceptionally snowy ones and has endured
some major early-season snowstorms. Chicago's snowiest November was in 1940
when 14.8 inches of snow piled up. That month turned out to be the snowiest month of
the entire 1940-41 winter season that went on to produce 52.5 inches of snow.

Thanks for joining us for this Wednesday edition of Before the Forecast! After showers brought a cool and dreary day for Chicago, we can expect to see a dive in temperatures the next few days. New storm Omar becomes a hurricane. As always, Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Mike McLaughlin of Roanoke, Indiana sends us this beautiful shot of the
fall colors in Maine. He snapped this shot September 29 in Soamsville,
Maine on Mt. Desert Island. It's beautiful--thanks for sharing this with
us, Mike!

Tom Skilling

Photo courtesy of Mike McLaughlin of Roanoke, Indiana

Curt Renz, who for year’s reported on business for WCIU with our friend and former WGN
alum Jack Taylor, is always wonderful in sharing his twin passions for astronomy and
photography for us. Curt sends us these shots taken from Arlington Height Tuesday
evening of the Hunter’s Moon. He snapped this 19 minutes after moonrise and 5 minutes
before sunset at 6:06 p.m. THANKS Curt!

Tom Skilling

Photos courtesy of Curt Renz, Arlington Heights

Rick Thoman, a Lead Forecaster at the National Weather Service Forecast Office in
Fairbanks, Alaska, shares this beautiful shot with us from Interior Alaska. Rick reports:

"The chinook last Friday and Saturday was warm enough to melt most of the snow in
town, but since then there has been 3-5 inches of snow. It cleared out overnite, with
valley site falling below zero. The low of 3 below this morning at Fairbanks airport is
the earliest first "zero" in the autumn since 1988, and the coldest this early in the
season since 1982. The Goldstream Valley CWOP site had 12 below, and North Pole had
11 below."

Many thanks, Rick, for the spectacular shot and for an update on the onset of frigid
weather in our beautiful 49th state!

Tom Skilling

Photo courtesy of Rick Thoman, Fairbanks, Alaska

Rains predicted to sweep the Chicago area Wednesday into Wednesday night drenched
the Plains on Tuesday. The wet system -- which combines remnant moisture from
Pacific Hurricane Norbert, which roared into Mexico this past weekend, and a fresh
supply of moisture from the Gulf of Mexico -- may produce one-half to 1 inch of rain
here before exiting Thursday. Kansas was hardest hit Tuesday with as much as 2.68
inches recorded near Scott City in southwest Kansas while El Dorado in the center of
the state suffered a 2-inch drenching.

Chilly air -- the coolest here since late May -- spills into the Midwest next. Daytime
highs Thursday and Friday may struggle into the mid-50s. Any clearing at night could
permit local 30s in outlying areas.

FAST INTENSIFYING OMAR THREATENING TO SWEEP PUERTO RICO, VIRGIN
ISLANDS AS A FULL BLOWN HURRICANE

Warm Caribbean waters threaten to turn the season's 15th tropical storm into a
Category-2 hurricane (Sustained winds of 96-110 m.p.h.)as it sweeps toward Puerto
Rico and the Virgin Islands. Hurricane watches have been issued.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,

While following the progress of Hurricane Ike and other hurricanes on a usually reliable
lightning detection website, I noticed few if any lightning strikes associated with the
hurricanes. Is this normal?

Brent Erwin

Dear Brent,

It is normal. Hurricanes contain very little, if any, lightning despite
popular belief to the contrary. The concept of "raging thunderstorms" in hurricanes is
erroneous.

Cumulonimbus clouds (thunderheads) become electrified when their vertical wind
currents cause raindrops and ice crystals to brush past each other; the "rubbing" causes
the particles to become charged. Hurricane winds, though, are mainly horizontal. They
lack the powerful, very localized vertical currents typical of thunderstorms. In addition,
hurricanes are tropical weather systems; they are warm throughout and they contain
little or no ice, even at great altitude.

Tracey Surface sent us these great pictures of Tuesday evening's full moon.

Thanks Tracy!

Photo courtesy: Tracey Surface

Our thanks to Jim Marocchi for more shots of the Chicago area's maturing
fall colors. Thanks Jim!

Tom Skilling

Photos courtesy of Jim Marocchi

Thanks for joining us for this Tuesday's edition of Before the Forecast! Cool spells hit in waves for this upcoming week here in Chicago land while a new storm Omar brews in the tropics. As always, Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Ellen Lytle, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Mike Frankowski’s photos are always a treat—and his newest set of photos is NO
exception. Check out Mike’s eye-catching collection of fall color shots taken Tuesday
in northwest suburban Busse Woods.

Thanks Mike!!

Tom Skilling

Photos courtesy of Mike Frankowski of South Elgin, Illinois

Gerard J. Fabrizius farms in Maple Park, Illinois and snapped these photos while out
doing morning chores. His wife Judy tells us Gerard is a hay farmer and points out the
photos reveal round bales of hay. Great shots! Our thanks to Judy and Gerard Fabrizius
for sharing these with us!

Tom Skilling

Photos courtesy of Judy and Gerard Fabrizius, Maple Park, Illinois

Barb Stover in far west suburban Elburn sends us this photo of the sharp demarcation
between clouds and clear skies Tuesday morning. The extremely well defined cut-off
between overcast and cloud-free skies was just as dramatic in appearance on satellite
images of our area. There are times when the juxtapositioning of moist and dry air
leads to this sort of sharp cut-off in a cloud deck—and this morning was clearly one of
them. Thanks for sharing this with us, Barb!

Tom Skilling


Photo courtesy of Barb Stover from Elburn, Illinois

It will seem a lot more like autumn than summer by the end of the week as weather
more typical of mid-October arrives on the scene. Sunday's record-tying highs in the
middle 80s will be long-gone, replaced by Saturday morning lows in the 30s that could
bring frost and even freezing conditions to areas away from Lake Michigan. The
downhill temperature trend will begin slowly on Tuesday and Wednesday as
temperatures remain in the 60s. Cooling gathers steam later in the week as highs fail to
break 60 from Thursday through Saturday.

Some light showers will accompany the first surge of cooler air early Tuesday, but a
more significant shot of rain is expected to move in Wednesday before a stronger
intrusion of colder air.

NANA FADES -- OMAR LIKELY TO BECOME A NAMED STORM TUESDAY

Tropical Storm Nana has weakened to a depression and will dissipate in the open
Atlantic later this week. Meanwhile, another depression gaining strength south of
Puerto Rico should become the season's 15th named storm, Omar, Tuesday. The
system's heavy rains already produced flash flooding in Puerto Rico on Monday.

--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,

What is the latest date of any 80-degree day here? How often has it reached that
temperature in meteorological fall?

Nick Recchia, River Grove

Dear Nick,

A computer scan of 138 years of Chicago's official temperature records dating from
Nov. 1, 1870, to the present reveals that every meteorological autumn (September
through November) has produced at least one day at or above 80 degrees. The same
can be said of meteorological spring (March through May) and summer (June through
August). An 80-degree day has occurred as early in the spring as March 3 (81 degrees,
1974) and as late in the autumn as Nov. 1 (81 degrees, 1950).

Winter (December through February) is the only season during which Chicago's
temperature has not reached 80. Nevertheless, the city's highest winter temperature is a
very unwintry 75 degrees (Feb. 27, 1976).

For the second straight year the Chicago Marathon was run in unseasonably warm
weather. Sunday's high of 84 degrees at O'Hare Airport tied the day's record high set in
1960, while Midway Airport's 86 equaled a previous 1930 benchmark. In 2007, the race
held on Oct. 7 was canceled after 3.5 hours when the mercury soared to a
record-breaking 87 degrees. The city had not experienced temperatures as high as
Sunday's in more than five weeks since a steamy 94 degrees on Sept. 2.
One more day of warmth is expected Monday, but more cloudiness should temper the
heat, holding readings closer to 80 degrees. More seasonable conditions will return for
the rest of the week as cooler weather moves in following the passage of a cold front
early Tuesday.

IN ATLANTIC, IT'S NANA -- THEN GOODBYE
Tropical Storm Nana, the 14th named storm of the season formed in the open Atlantic
Sunday afternoon about 900 miles west of the Cape Verde Islands. However, Nana is
expected to meet a quick demise as the storm encounters strong winds aloft. In the
Caribbean, forecasters are watching another system south of Puerto Rico that may
strengthen into Tropical Storm Omar.
--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
I remember several inches of snow falling in Chicago in October when I was a
kid. I'm guessing that it was in the early 1950s. Can you verify this event?
Bill Renner
Dear Bill,
The year was 1952 when 3 inches of lake-effect snow fell in the Chicago area
during the early morning hours of Oct. 20. A strong cold front passed
through Chicago late on Oct. 19 and temperatures plummeted as strong north
winds gusted to 40 m.p.h. The strong winds produced high waves on Lake
Michigan that flooded portions of South Lake Shore Drive. As the temperature
dropped, snow began falling shortly after midnight and continued into the
morning. Despite the still-warm ground the snow accumulated -- especially on
grassy areas. After a subfreezing morning low of 29 degrees, the temperature
climbed to 41 degrees, and the record early season snowfall was nothing more
than a melted memory.

Two years ago today the Chicago area was hit by the earliest measurable snow in its
history. Officially 0.3 inches of snow fell at O'Hare Airport, but many suburban areas
received more than an inch of snow on a day that saw a high of 39 and a low of 30.

Click here for Tom Skilling's full report and weather photos from Oct. 12, 2006

In contrast, today the city is basking in summerlike warmth with temperatures topping
the 80-degree mark.
--By Steve Kahn, WGN Weather Center Meteorologist

The first snow of the season hit Cedar City Utah this weekend.
--By Steve Kahn, WGN Weather Center Meteorologist

Photo by Gail Miller

It won't be as hot and humid as last year's heat-shortened race, where readings soared
to the middle 80s before noon. But runners competing in Sunday's 31st Chicago
Marathon will still have to contend with late-morning temperatures in the 70s as warm
weather dominates race day for the second straight year. Highs on Sunday should top
out in the lower 80s, compared to last year's record-breaking 87-degree high.

After failing to reach 70 degrees in October's opening nine days for the first time since
1977, the high reached 72 degrees on Friday and 79 Saturday, setting the stage for at
least four straight 70-degree-plus days before the next cooldown arrives Tuesday.
High temperatures should then slowly fall through the 60s the rest of the week as more
seasonable weather returns.

WINTER ARRIVES EARLY IN THE WEST

An early-season storm is bringing the first snows of the season to the northern
portions of the Rockies and High Plains. More than 2 feet of snow has buried portions
of Wyoming and Montana with another foot expected in many areas before the storm
ends. Boise, Idaho received 1.7 inches Friday, its earliest measurable snow since 1898,
when records began there.

--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
How often has Chicago moved its official site for weather records?

Natalie Strauss

Dear Natalie,

Since the beginning of weather records here on Oct. 15, 1870, the city’s official climate
site has moved 13 times. The first official observations were taken at what is now 181
W. Washington St. from Oct. 15, 1870, until it was abandoned on Oct. 8, 1871, during
the Great Chicago Fire. After the fire, several downtown locations served as the official
site with the longest tenure at the U.S. Courthouse at 219 S. Dearborn St. Records
shifted to Rosenwald Hall at the University of Chicago on Jan. 1, 1926, until a move to
Midway Airport on July 1, 1942. Midway was the official site until a relocation to O’Hare
International Airport on Jan. 17, 1980. The official station has been moved around
O’Hare three more times, reaching its current location on Feb. 1, 1996.

The weather's beautiful on the Door Peninsula this weekend. So reports Anson Mount
who shares this Friday evening (October 10) sunset with us. THANKS as always, Anson!
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Photo courtesy of Anson Mount

The weather doesn't get much nicer here in October. Chicagoans are in line for a
weekend likely to be the warmest of any until next spring.
Temperatures, which peaked at 72 degrees at O'Hare International Airport on Friday --
the warmest here in 13 days and October's first 70-degree-plus reading -- head even
higher Saturday and Sunday. The mid- and upper 70s predicted in all but immediate
lakeshore locations represent an increase of 16 degrees warmer than last weekend and
run at levels more than 20 degrees warmer than the same period a year ago. While
highs of 75 and 78 degrees are predicted Saturday and Sunday, readings only reached
54 and 59 degrees a year ago.

MONTANA, WYOMING SNOWS ONLY BEGINNING
AND ALREADY UP TO 16" DEEP
The irony of this weekend's exceptional weather is that autumn's most powerful storm
to date is behind the warm south to south winds helping to buoy temperatures.
That system is hammering the West with weather advisories across 13 states. Snowfall
by late Friday had reached 16 inches at Nye, Mont., where wind gusts were clocked at
40 m.p.h.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Last week we saw what appeared to be frost on our rooftops in the early
morning even when temperatures were not even close to 32 degrees, and
probably much warmer on the roof of the house. Was that really frost?
William Brown, Aurora
Dear William,
It was frost. Frost forms when a layer of air cools below freezing and below
its saturation temperature by contact with a cold surface which itself has
chilled to a subfreezing temperature. Airborne water vapor condenses
directly, in ice crystal form, onto the cold surface and frost forms. (Frost
is not frozen dew.)
Under clear, calm, chilly nighttime conditions, surfaces like blades of
grass (but it works for rooftops, too) radiate a great deal of heat and
their temperature will drop sharply. If there is no wind, a thin layer of
very cold air develops, sometimes an inch or less in depth, and it is here
that frost forms.

Thanks for joining us for this Friday edition of Before the Forecast! This weekend looks great for the Chicago Marathon. Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Autumn is always a beautiful time of the year -- and nowhere more so than in Wisconsin
where this year's fall colors are out big time! Check out these photos from our friend Dan
Hanson in Winter. Wis. The community of Winter is located in northwest Wisconsin
approximately halfway between Eau Claire and Chippewa Dan and the Wisconsin/Upper
Michigan border.

Dan tells us colors there peaked last weekend -- but as you can see from his terrific
shots, there is still real beauty on display for all to see. And the spread of this season's
fall colors is evident elsewhere in Wisconsin south to the Chicago area! Our THANKS to
Dan for the great shots!
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Photos courtesy of Dan Hanson, Winter, Wisconsin

The official high temperature at O'Hare missed 70 by just a degree Thursday. It's 31
years since the opening nine days of October have failed to produce a single 70. It's a
string likely to be broken away from Lake Michigan Friday. Though southeast winds off
Lake Michigan are likely to temper lakeside highs, the warmest inland readings should
reach the mid-70s, thanks to an abundance of sun. A series of three additional 70s are
likely to ensue this weekend through Columbus Day, producing the area's longest
70-degree streak this late in the season in eight years. Friday's predicted 72-degree
high is to be the mildest in 13 days.

A powerful storm is pounding the West. Snows may accumulate more than a foot in the
hardest hit locations of Wyoming and Montana while 1-3 inches of rains in sections of
the Dakotas would be the equivalent of two Octobers worth of rain.

HAIL POUNDS SOUTHEAST THURSDAY: CALIFORNIANS WARY OF POWERFUL
WINDS, WILDFIRE THREAT

Nearly 20 reports of hail peppered sections of Georgia, Florida Thursday, including
baseball-size hail at Rochelle, Ga. which damaged automobiles.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Did Mrs. O'Leary's cow really start the Chicago fire?

-Jim Morris

Dear Jim,

Historians agree the Chicago Fire of Oct. 8-10, 1871, originated in the O'Leary barn,
but it is not clear that Mrs. O'Leary's cow kicked over a lantern. Daniel "Peg Leg"
Sullivan claimed in an inquiry on Nov. 25, 1871, he saw the cow start the fire. However,
investigation has since revealed Sullivan's testimony contained many inconsistencies;
the possibility that he himself started the barn fire is very real.

Regardless of the cause, Chicago was a tinder box waiting to ignite that
October. Only 0.74 inch of rain (19 percent of normal) had fallen in the five weeks
leading up to Oct. 8, a warm and very windy day with low humidity. Professor Increase
Lapham of the Chicago Weather Bureau later commented, "A dry season, a strong wind,
and an accidental fire, whenever they occur together, will do the work."

Thanks for joining us for this Thursday edition of Before the Forecast! We have quite a contrast in weather across the country. A nice warmup in time for the Chicago Marathon as well as big snows forecast for the west. Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather interns Aaron Brackett and Ellen Lytle, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

The dry air in place across the Chicago area has cooled overnight, contributing to
Thursday's daybreak chill. Highs Wednesday struggled to reach 64 degrees -- a
situation that is about to change. Areas away from Lake Michigan are in line for a string
of five 70-degree afternoons, which would be the longest late season 70-degree string
in eight years. October's cool open has been unusual and well below the same period a
year ago. The month has failed to produce a 70-degree high to date, something that
has happened here only once in the last half-century.

The warmth predicted in coming days is linked to a buckling jet stream out West
brought on by a southward plunge of cold early season air. The process is to produce a
powerhouse autumn storm that could drench the northern Plains with the equivalent of
two Octobers worth of rain while burying the northern Rockies under as much as 1-2
feet of snow. The system shifts Chicago winds southeast in coming days -- then
southerly over the weekend, promoting warmer and more humid conditions here.

POWERHOUSE PACIFIC HURRICANE NORBERT MAY SEND RAINY REMNANTS
INTO MIDWEST

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
What are the sunniest and cloudiest months of the year in Chicago?

Kelly Spong Arlington Heights

Dear Kelly,

Thanks to the continuing efforts of Midway observer Frank Wachowski, Chicago has
one of the best sunshine data bases in the nation dating to 1893. Wachowski notes, not
surprisingly, that the sunniest months here are in the summer. June and July lead the
year, averaging 68 percent of possible sunshine followed by August with 64 percent.
The city will shortly be approaching the cloudiest time of the year, with November and
December averaging 40 percent and 39 percent respectively. The sunniest month on
record here was July 1916, when nearly cloudless skies allowed 95 percent of the
possible sunshine to bathe the city. In contrast, a scant 16 percent of the possible
sunshine reached the city in November 1985.

Thanks for joining us for this Wednesday's edition of Before the Forecast! Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Eric Szos, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Connie Kohler e-mails us with this BEAUTIFUL shot of the fall colors in Waupaca,
Wisconsin! Many thanks Connie!

Tom Skilling

Photo courtesy of Connie Koehler, Waupaca, Wisc.

The first sticking snow arrived at Valdez, Alaska Tuesday. Dave Noble, who lives there,
sends us these great photos from our 49th state and writes :

“I have been an avid reader of your blog for 2.5 years now. I live in Valdez and work for
the National Weather Service. On Tuesday Oct 6th, we had our first measurable
snowfall.. 2.3 inches. Since 1972, we had never received snow on that date before. I
thought I would send you some pictures. There was a Grizzly bear outside of town that
morning sniffing around for dead silver salmon to devour while seagulls and eagles
looked on. We (the onlookers) were around 50 yards away from the bear...”

Dave—you're great to share this information with us! MANY THANKS and please don't
hesitate to write us or send pictures anytime! All the best!

Tom Skilling

Photos courtesy of Dave Noble, Valdez, Alaska

Rainfall topped one inch at a number of locations Tuesday, the biggest tallies since
0.82 inches fell at O'Hare International Airport on Sept. 29. The clouds and precipitation
cut deeply into daytime warming, limiting Chicago's high to 63-degrees. The heaviest
preliminary totals at Weather Bug rain gauges in the area included 1.02 inches at
Palatine, 0.89 inches at Oak Lawn, 0.82 inches at Evergreen Park and 1.18 inches at
LaPorte, Ind. COOP Patrick Skach in Oak Brook reported 0.81 inches through 9 p.m. --
and it was still raining. O'Hare's rain tally of 0.54 inches through 8 p.m. pushed the
meteorological autumn tally (since Sept. 1) to 14.24 inches -- the heaviest in 138 years
of official Chicago weather records.

MILD MARATHON AHEAD SUNDAY -- BUT 12 TO 14 DEGREES BELOW A YEAR
AGO

Cold air crashes into the West in coming days setting the stage for big northern
Rockies snows, but warming Chicago into the 70s this weekend. The pattern includes
milder than normal Chicago Marathon weather Sunday -- though cooler than last
year's heat-plagued event which was suspended after 3.5 hours.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,

During my childhood in the early 1950s I remember spending most of my summers in a
swimming pool during very hot weather. Could you characterize the summers of the
1950s?

-John Skaritka Elgin

Dear John,

You were not alone in trying to escape the heat during the hot summers of the 1950s.
Based on average temperature, five of the city's all-time 10 warmest summers (June,
July, August) occurred during the '50s. The summer of 1955 with an average
temperature of 76.4 degrees holds the honors for being the city's warmest. That year
the city logged 46 days where the mercury reached 90 degrees or higher. Other
summers that decade with a lot of 90 degree plus days included 1953 (42), 1959 (39),
1952 (38), and 1954 (36). Based on Midway Airport data, the '50s brought Chicago
276 days of 90 degrees or higher, second only to the "Dust Bowl" years of the 1930s
that recorded 343 such days.

Thanks for joining us for this Tuesday's edition of Before the Forecast! Huge temperature changes are in store for this upcoming week through out the nation. Tom Skilling has all the details on Tonight's BTF. A big thank you goes out to our weather intern Ellen Lytle, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

An photo update taken by Anson Tuesday in Orlando.

The cool nights of recent weeks have encouraged the development of fall colors. Though
still patchy, Chuck Hagen of Oak Lawn, Illinois managed to capture these examples near
Maple Lake in Hickory Hills and shares them with us. Thanks Chuck!!

Tom Skilling

Photos courtesy of Chuck Hagen

Bruce Devick sends us this picture of a hole created in a cement platform located near a
barn in Newark, Illinois by a lightning strike a week ago Monday (on September 29). Bruce
reports the hole measures four by five feet and that it’s 14 inches deep and says the
platform and a barn 20 feet away were struck simultaneously by the same lightning bolt.
Lightning is often known for the vagaries with which it strikes and this is certainly an
instance which illustrates why. THANKS for sharing this with us Bruce!

Tom Skilling

Monday's 69 degrees was Chicago's warmest official high in nine days -- a welcome
development in an October that has averaged nearly 16 degrees cooler than a year ago.
The month's opening six days have been the coolest of any October in four years. The
day's southeasterly winds limited Monday's warmest readings to inland areas. Weather
records suggest it may be three weeks before 70s disappear from the scene here. Over
the last 10 years, Oct. 26 has been the average date of the year's final reading in the
70s -- though a 72-degree high occurred Nov. 18, 1999.

The fall harvest is under way on many area farms, though well behind the five-year
average on a statewide basis. The USDA reported Monday that 10 percent of the state's
corn and 22 percent of its soybeans have been harvested -- well behind the respective
averages of 47 percent and 48 percent over the last five years.

SOUTHBOUND ALASKAN CHILL TO SET STAGE FOR BIG ROCKIES/PLAINS
SNOW

The season's coldest air dropped the temperature at Anaktuvak Pass in Alaska's Brooks
Range to 7 degrees. The southward plunge of that cold air sets the stage for a Rockies
and western Plains snowstorm.

--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
You publish a single high and low temperature forecast for Chicago. What site is that
for, and with all the variability around the Chicago area, how can you do that?

Jay Wait

Dear Jay,

The daily temperature forecasts are made for the city's official climate site at O'Hare
International Airport. However, great detail is provided in the supporting text to convey
the variability in weather that frequently exists around the vast metropolitan area,
further complicated by the proximity of Lake Michigan.

Temperature ranges are given from areas far inland to locations downtown or near the
lake or from far north to far south, depending upon the temperature distribution.
Efforts are made to pinpoint where the heaviest snow or rain is expected to develop.
Often winter storms track close to city bringing heavy snow to the northern suburbs, a
slushy mixture to the city and rain to southern sections.

Thanks for joining us for this Monday edition of Before the Forecast!
A big thank you goes out to our weather intern Eric, for helping us out with tonight's video.

For complete weather information, tune in to WGN News at 9pm and wgntv.com for Tom Skilling's Full and 7-day forecasts.

Tune in tomorrow for another edition of Before the Forecast, and as always continue
to watch WGN for more coverage: Morning, Noon & Nine.

Our friend, pilot Anson Mount, shares this shot of a thunderstorm bearing down on
Orlando, Florida Monday. The National Business Aircraft Association is holding its
convention there. Anson says he snapped this photo of the approaching thunderstorm
from his 16th floor hotel room. Thanks Anson!

Tom Skilling

Photo courtesy: Anson Mount

Chicagoans, it would seem, are growing accustomed to wet weather. The city struggled
through the second-wettest September in 138 years of Chicago weather history, and
computer models now suggest another rainy pattern is establishing itself this week.
Don't expect a repeat of September's deluges, but be advised that rain is mentioned in
Chicago's weather forecasts on five of the next seven days.
Two distinct storm systems head our way this week. The first, the weakened remnant of
a powerful system that blasted into the Pacific Northwest, brings rain to Chicago
Tuesday and Wednesday. Cold air accompanying that system put 10 to 20 inches of
snow across some of the higher mountain elevations of Colorado on Sunday.

WASHOUT NEXT WEEKEND?
Computer models indicate that yet another storm system has Chicago and the Midwest
in its sights toward the weekend, and early indications are that it could be a real
drencher. A strong storm -- slow-moving and dripping with moisture from the Gulf of
Mexico -- is likely to bring rain into the area late Friday, with possibly significant rain
totals occurring on Saturday, Sunday and Monday.
--By Richard Koeneman, WGN Weather Center Meteorologist

Dear Tom,
My hay fever is getting worse year by year and doctors say the ragweed
pollen count is increasing. How is the weather causing this?
Irene Stack
Dear Irene,
It's not the weather but rather the steadily increasing concentration of
carbon dioxide (CO2) in the air. CO2 greatly stimulates the growth rate of
plants and their production of pollen, including ragweed. Atmospheric CO2
has increased 31 percent from 294 parts per million (ppm) in 1900 to 384 ppm
now. In response, ragweed (the source of pollen that triggers hay fever) has
doubled its pollen production since 1900. Dr. Paul Epstein of Harvard
University's Center for Health and the Global Environment, says, "This
carbon dioxide stimulation of plants has a side effect for public health,
(causing) hay fever, conjunctivitis and ... asthma."

A powerhouse storm system, the first major autumn storm of 2008, is barreling from
the Pacific Northwest into the Intermountain Region of the West Sunday. This system
will eventually be a significant player in Chicago’s weather. We’ll experience increasing
southeasterly winds and warmer temperatures starting Sunday. Southeast winds,
though, are lake winds for northern portions of metropolitan Chicago, so the northern
suburbs will experience much less temperature moderation Sunday than western and
southern sections. Rain and thunderstorms will overspread the area from south to north
by early afternoon and continue Sunday night as the western storm system shifts into
the Great Plains. Mild air will arrive in strength Monday and will persist through Tuesday
in advance of the western system.

Looking ahead, rain will push to the east of Chicago by Thursday as cooler, drier air of
Canadian origin arrives, but computer models suggest the cool interlude will be
short-lived. Milder air stages a return on Friday and carries afternoon temperatures into
the 70s by the weekend. It's not even out of the question that Chicago might see
another 80-degree day next Sunday.

Dear Tom,
I have seen photographs of lightning bolts flashing through giant clouds of ash rising
above erupting volcanoes. Is this trick photography? A lot can be done with computers
these days to alter photographs.
Jack Larsen, Chicago

Dear Jack,

The number of lightning flashes that occur worldwide in any given year is
immense—literally hundreds of millions of them. The annual tally just in the United
States runs at more than 100 million. An overwhelming majority of those bolts are
“standard” lightning flashes associated with thunderstorms, but friction between sand
particles in sandstorms will occasionally generate electric charges sufficient to produce
lightning. Lightning also frequently flashes through ash clouds above erupting
volcanoes for the same reason. The photographs you saw were probably not doctored.

Clear skies and light winds under cold high pressure Friday night created near-perfect
radiational cooling conditions.
As a result, early Saturday morning temperatures in the mid to upper 30s and scattered
light frost were expected across northern Illinois. Frost warnings were issued for all of
Wisconsin with early morning readings just north of the Illinois-Wisconsin border
forecast in the lower 30s. East to southeast winds on the backside of cool Canadian
high pressure centered over the northeastern United States will hold over northeast
Illinois this weekend. But as the high slowly loses its grip and moves off the New
England coast, Chicago will experience a gradual moderation of temperatures. Highs on
Saturday will not be that much different than Friday's levels, but Sunday should see the
readings reach the "normal" level (67 degrees) for the first time in a week.

INCREASING TEMPERATURES,
CHANCE OF SHOWERS EARLY NEXT WEEK
As warmer, more moist air approaches from the west, Chicago's early workweek
weather should feature above-normal temperatures and a good chance of showers and
thunderstorms.
--By Paul Dailey, WGN Weather Center Meteorologist

Dear Tom,
On Jim Ramsey's WGN-TV weathercast a few years ago, he showed satellite
photographs in which cloud cover almost exactly matched the shape of the
Great Lakes. Other areas were clear but clouds over the lakes matched the
shape of the lakes. I found it very interesting. Cold weather effect?
Sharon Hrycewicz, Batavia
Dear Sharon,
Cold-weather effect it was. Very cold air over relatively warm water
stimulates the development of cumulus and stratocumulus clouds over the
water. It's practically a daily occurrence in the Great Lakes region during
the winter.
Usually, though, brisk winds constantly transport those clouds downwind and
over land. Sometimes, as in the situation that caught your attention,
minimal air motion allows the clouds to hover right where they form: over
the water.

The cool and rather moist air that has bathed the Chicago area in recent days is forecast to yield, albeit slowly, to moderately higher temperatures in the days ahead as the national weather regime shifts gears. For several days, the West has been warm, even hot, and the East has been cool and wet.

That's about to change, and the transition will take place this weekend. Milder air
begins filtering across the Chicago area this weekend, and by Monday the warming
trend is expected to carry temperatures into the 70s.

But there's a complication: Mild air arrives on the wings of brisk southeast winds,
raising the possibility of lake-induced cooling in Chicago's North Shore.

FROST ADVISORIES IN UPPER MIDWEST

National Weather Service offices have posted frost advisories across portions of
Minnesota and Wisconsin for the early-morning hours Friday. Patchy frost is in the
cards again early Saturday morning for much of the Upper Midwest, including northern
Illinois and the typically colder outlying areas of metropolitan Chicago.

--By Richard Koeneman, WGN Weather Center Meteorologist

Dear Tom,
My 10-year-old son asked, "Why does the sky turn green before a tornado comes?"

Charlie and Eric Mayer

Dear Charlie and Eric,

No one really knows for sure, but this much is certain: The greenish tint that
sometimes accompanies cloud structures in thunderstorms is not associated with
tornadoes. Many tornado-producing thunderstorms do not appear green and most
green-tinted thunderstorms do not produce tornadoes.

Please explain to your son that "green thunderstorms" are not reliable indicators of
tornadoes. Recent research suggests the greenish tint of some thunderstorms occurs
when they contain an especially great amount of water. Water selectively absorbs most
of the colors in sunlight but scatters out the green light. When sunlight passes through
such a storm, a disproportionately great amount of green light reaches our eyes.

Chicago’s October temperatures undergo the second-largest monthly decline of the year,
surpassed only by November.

EXTREME MINIMUM SUNSPOT ACTIVITY
Astronomers who keep tabs on sunspots—the dark blotches usually scattered across
the sun’s surface—have observed a recent extreme minimum of sunspot activity.
Sunspots run in 11-year cycles, but the current lull is exceptional (though not without
historical precedent). As of Sept. 27, NASA scientists report that the sun has been
absolutely blank—no sunspots at all—for 200 days in 2008.
NASA’s David Hathaway says, “Sunspot counts are at a 50-year low. We're experiencing
a deep minimum of the solar cycle.” The 11-year solar sunspot cycle is apparently not a
factor in the Earth’s weather because there is no known 11-year-cycle counterpart in
our weather.
--By Richard Koeneman, WGN Weather Center Meteorologist

Dear Tom,
The coldest temperature recorded in Antarctica is -129 degrees, and carbon
dioxide (CO2) freezes at -71. Has it ever snowed CO2 in Antarctica, or is
the percent of CO2 too low?
Alison Drabik, Oak Forest
Dear Alison,
Indeed, CO2 gas freezes at -71 degrees and winter temperatures in Antarctica
routinely drop below that frigid value, and on rare occasions in the Arctic
as well.
Meteorologist David Cook in the Climate Research Section at Argonne National
Laboratory in DuPage County says, "Certainly, at least some of the CO2 in
the atmosphere at the poles does freeze out (of the air) during the winter.
However, there is not enough frozen out to accumulate to any extent." This
is because Antarctic temperatures, as bitterly cold as they are, do not
remain below -71 degrees for much of the year. Also, atmospheric CO2
concentration is vanishingly sparse, at a meager 0.0385 percent.