February 2009 Archives

March is the month when Chicago begins its transition from winter to spring in earnest,
with normal temperatures on a steady rise (from a high of 41 degrees on March 1 to 52 on
the 31st). March 2009's opening week will mirror this pattern, starting out cold and
blustery with periods of lake-effect snow Sunday, but quickly morphing into a mild, rainy
pattern with highs well into the 50s by next weekend. Before the warm-up, strong north-
northeast winds blowing cold air down the full length of Lake Michigan will set up a
potential for some accumulating lake-effect snow in lakeside counties.
TWISTERS HIT ALABAMA; MAJOR SNOW TARGETS SOUTH AND EAST
A developing storm system brought at least three twisters to east-central Alabama
Saturday. This same storm is expected to bring heavy snowfall to much of the South and East
Sunday and Monday blanketing areas from Alabama, Georgia and Tennessee to New England
including the major cities of the Northeast.
On Saturday, this storm produced more than 9 inches of snow at Salem, Mo., located
southwest of St. Louis. Snow and sleet also fell from Arkansas across western Tennessee and
northern Mississippi.
--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
Sometimes March "comes in like a lion." What is the worst March 1 weather that Chicago
has experienced?

Red McCarthy, Plainfield

Dear Red,
It is hard to pick Chicago's worst March 1, but we can offer some strong contenders. In
both 1947 and 1948, March arrived with a major snowstorm. In both years the snow
continued into March 2, bringing the city more than 7 inches. March's opening in 1932
was raw, damp and blustery—temperatures were in the 30s with gusty northeast winds the
city was soaked by nearly an inch of rain. And just two years ago in 2007, 1.09 inches of
rain doused the city. In 1962, March opened as a "cold lion" with a high of 18 degrees and
a low of 5 below zero. Of course, there have been some years when March opened like a
lamb. One of the nicest was in 1992 when the high soared to 71 degrees.

Record books in Chicago close Saturday night on the coldest December through February
meteorological winter of the past 23 years. The season has averaged 22.1 degrees -- colder
than last winter's 24.8 and well below the long-term average of 26.7. February has been
the least harsh of the three-month season, but Saturday's 30-degree high will fall
nearly 10 degrees below normal.
A modest lake-effect snow setup produces a few flurries Saturday morning as a
better-organized snow system sinks southeastward from Nebraska through Memphis -- with snow
possible all the way to Atlanta. Chicago's lake-snow potential rises Sunday. Winds coming into
the city from the north will travel four times the distance over water as compared to
Saturday and with a much sharper temperature drop as altitude increases -- signs that
lake-snow formation may be more vigorous.
2009'S 1ST 100-DEGREE READING IN U.S.
A sure sign of the upcoming warm season is the nation's first 100-degree-plus reading of
2009, recorded Friday at McAllen, Texas. It was the earliest-ever triple-digit high for
McAllen and beat the old record (set March 6, 1956) by a week.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Early afternoon on Jan. 21 the national radar picture showed some snow off
of lakes Erie and Ontario, and patchy rain over California, but nothing
elsewhere. Has there ever been a time when the whole nation was dry?
Joseph Morgenstern
Dear Joseph,
Precipitation-free periods might occur across the 48 contiguous states,
though only rarely and briefly.
Retired meteorologist Robert Johns, a 40-year veteran with the Storm
Prediction Center, says, "The most likely period for a few dry hours would
be the fall (probably late September or October) after low-level moisture
has been swept out of the nation and before the cold blasts needed for Great
Lakes snow/rain bands have developed. During this period you would need a
west-to-east weather pattern with the jet stream displaced north into
Canada, possibly with a weak high pressure system over the north and central
Plains."

--WGN-TV Weather Center

Photo courtesy of Amy Rowan

Standing water was everywhere late Thursday in the wake of blinding downpours delivered
by building-rattling thunderstorms. The city's official rain tally at O'Hare Airport had
reached 1.90 inches by 9 p.m. -- an amount well beyond the 110-year-old Feb. 26 record of
0.92 inches. The deluge closed area roads and prompted flood warnings. The rainfall was
more than typically falls in an entire February and becomes the second heaviest February
rain event in 138 years. Midway Airport's 1.60 inches was also a same-day record,
eclipsing the 0.87 inches in 1971.
Plunging overnight temperatures threatened to turn standing water to ice, and motorists
and pedestrians were being advised to approach Friday morning's commute with caution. The
one consolation for many weary of winter was that Thursday's precipitation was liquid
and not 20 inches of snow, which could have occurred at lower temperatures.
LATE SEASON ARCTIC CHILL IN PLACE
March will open on a wintry note Sunday as strong arctic high north of the Great Lakes
sends an icy blast of northeast winds into the Chicago area causing bands of lake-effect
snow showers to develop here by Sunday evening.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
What is the average date of the last snowfall? What is the earliest date that we have
been done with snowfall for the season?
Nick Recchia, River Grove
Dear Nick,
Spring is fast approaching and the recent smattering of mild days has raised hopes that
the harsh winter we've been enduring is finally behind us.

However, Chicago's snow history suggests caution is in order. Snowfall records dating
from the winter of 1884-85 provide these sobering statistics: Chicago's average last
date of measurable snow (0.1 inch or more) is April 3 --- five weeks away. March runs
a 96 percent chance of bringing measurable snow, and in April it's 52 percent.
Measurable snow has fallen as far into the spring as May 11 (0.2 inch on May 11, 1967).

At the opposite extreme, the city's snow season ended as early as Feb. 27 in the mild
"El Niño" winter of 1996-97.

Leave it to our friend Ryan Szekeres to send us beautiful shots like
these! Wednesday's mild weather--the warmest here in two weeks--was a
treat for all--even this Hawk which Ryan photographed on Northerly
Island along Chicago's beautiful lake front Wednesday. Thursday's rain
and downpour-generating thunderstorms accompanying chilly, raw winds off
still icy Lake Michigan couldn't be more different than the sunshine
picture here just yesterday! Thanks for the great shots, Ryan!

Tom Skilling

Photos courtesy of Ryan Szekeres, Chicago

Wednesday's mild weather appeared to do the trick in encouraging these flowering Winter
Aconite plants from the ground in the garden of Cathie and Gerry Klemm in Geneva,
Illinois. Gerry reports he expects to have 300 of these little beauties in a few weeks!
THANKS Cathie and Gerry for providing us wonderful visual evidence that spring is really
on the way—and good luck with garden this year! We’re sure it’s going to be terrific with
your green thumbs nurturing it!

Photos courtesy of: Cathie and Gerry Klemm

The Chicago area's biggest precipitation- producer in nearly two months is on its way.
Rainfall commences toward midday and should build in short order into heavy downpours that
may grow thundery late in the day. At the same time, a snowstorm is to wallop an area to
Chicago's north, from the the Dakotas through the Twin Cities into northern Wisconsin
and Michigan.
The new winter storm producing the cocktail of precipitation was centered in Colorado
late Wednesday. It's the byproduct of a 100-degree north/south temperature spread.
Wednesday readings ranged from below zero on North Dakota's border with Canada to the 90s in
southwest Texas.
A shallow layer of cold air has temporarily returned to Chicago and threatens some sleet
or freezing rain at the onset of precipitation Wednesday -- especially in the north and
west suburbs. But a northbound warm front could send 50s back into the city after dark
ahead of a late-night temperature plunge.
AREA TREATED TO WARMTH WEDNESDAY
O'Hare's 54-degree Wednesday high was the city's mildest reading in two weeks and the
warmest Feb. 25 in eight years. Gary reported a high of 59 and New Lenox hit 58.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Is it just me, or has this winter been more sunny than usual?
Mark
Dear Mark,
Chicago weather historian Frank Wachowski confirms your suspicions: This winter has
been considerably sunnier than usual. That's a ray of good news in a winter that in
other respects has been quite harsh by historical standards. Wachowski reports that, as
of Tuesday (Feb. 24), this winter (Dec. 1- Feb 24) has been the 18th sunniest since the
inception of sunshine records in the city in 1894 (115 years ago).

Winter days are "shorter" (that is, the hours of daylight are fewest at that time of year)
and winter is also Chicago's cloudiest season -- a double whammy that makes this
time of year seem especially gray and gloomy. As of Tuesday, Chicago's sunshine this
winter stood at 51 percent of the maximum amount possible, versus a normal winter
reading of 43 percent.

Chicago's temperatures take off in Wednesday's gusty southerly winds -- reaching the
highest levels in two weeks. The warm-up is being driven by the same air mass behind
Tuesday's temperature surge in the nation's mid-section, which saw readings in the 70s in
Nebraska and in the 90s in western Texas, where highs included 94 degrees at Ft. Stockton and
Pecos -- and a record-breaking 90 at Midland.
A major winter storm comes together Thursday and Thursday night in the Plains and
Midwest. Computer models predict 60+ m.p.h. southerly winds from the Gulf of Mexico north to
Illinois by late Thursday -- a flow expected to act as an atmospheric conveyor belt for
moisture. More than an inch of evaporated moisture is to reach the Chicago area.

THREAT OF MORE PRECIPITATION THAN IN A TYPICAL FEBRUARY
With abundant moisture and tremendous atmospheric lift there is a growing potential for
thunderstorms and heavy rainfall. A normal February produces 1.63 inches of liquid
precipitation here and totals from this storm could easily top that amount.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Has Chicago ever had a winter in which it recorded 20 inches of snow in three separate
months?
Pat Byrne Hoffman Estates, Ill.

Dear Pat,
A winter with three months of 20-inch plus snowfall has never occurred in the Chicago
area since records began in the winter of 1884-85.

The closest we've come was back in the winter of 1977-78 when only January, with
32.3 inches, exceeded the 20-inch threshold, but that December logged 19.2 inches
and February 19.7 inches.

So far this winter we've received more than 20 inches of snow in both December (21.9)
and January (21.5), but to date February has produced only a meager 4.5 inches. Unless
March or April turns out to be a blockbuster month for snow, the city's record of never
recording three 20-inch snow months in one winter will continue.

It's been five days since Chicagoans have been treated to a temperature above 32
degrees. A subfreezing spell spanning five days occurs this late in the season an average of
once every five years. Coming as it has in the midst of an especially harsh winter, it's
little wonder predictions of 40- and 48-degree highs Tuesday and Wednesday are raising
Chicagoan's spirits. Despite a February weather pattern less extreme than December or January,
the latest stats on the 2008-09 meteorological winter season, which began Dec. 1, rank
it among the city's harshest 12 percent over 139 years of official weather observations.
Temperatures have averaged 21.4 degrees -- the coldest in 23 years -- and Chicago's
current tally of 48.5 inches of snow is the most in the three decades since the infamous Jane
Byrne/Michael Bilandic 1978-79 snow season that ended up producing 89.7 inches.
SOUTHWEST SIZZLES, TUCSON TOPS LIST
While Chicago was locked in a late-winter chill Monday, record warmth covered portions
of the West. Tucson's 91 degrees fell just one degree short of the all-time February high
there. Records also fell at Winslow, Ariz. (76), and Bozeman (61) and Helena (60), both
in Montana.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
On a recent Hawaiian trip the paper not only listed the actual time of sunrise and
sunset but also times for civil, nautical and astronomical twilight? Can you explain?

Joe Kirasich western Springs
Dear Joe,
The time of sunrise and sunset is defined as the moment when the top of the sun's disk
is on the horizon. Civil, nautical and astronomical twilight are defined as when the sun
is six, 12 and 18 degrees below the horizon, respectively, as it is rising or setting. The
times as determined by U.S. Naval Observatory are used to define the gradual changes
in visible light that occur between total darkness and sunrise or sunset. Astronomer
Dan Joyce tells us that there are small time variations during the year, but there is
generally a period of almost 90 minutes for the transition from total darkness to
sunrise or from sunset to total darkness.

As the jet stream pattern gradually shifts from a northwest to more westerly flow the
next couple days, a cold Canadian high pressure air mass will move east. As a result,
southerly winds will return to the Midwest beginning tonight, and temperatures will begin to
rise Tuesday.
By Wednesday, northeast Illinois will have experienced some 48 hours of south winds, and
much of the snow cover -- especially southern portions -- will have melted. The melt
will accelerate as the air mass becomes more moist and showers develop. Under the right
circumstances, highs on Wednesday could well exceed 50 degrees -- but cloudy skies, scattered
showers and energy spent on melting snow all will work to restrict warming.
COLD AND SNOW RETURN THURSDAY
As a cold front eases through the area Thursday, winds will shift northeast off Lake
Michigan, and a steady light rain will probably change over to snow Thursday night. The
center of coldest air will hold to the north, but Chicago will sit in the southern flank of
the cold high pressure still partially under the influence of low pressure passing to the
south. That low may bring snow here Friday night and Saturday.
--By Paul Dailey, WGN Weather Center Meteorologist

Dear Tom,
The boiling point of water varies with air pressure. What about the freezing
point?
Russ Scott, DeKalb
Dear Russ,
Changes in air pressure do affect the freezing point of water, but the
effects are vanishingly small.
Dr. Christopher Grayce, Professor of Chemistry at the University of
California (Irvine), explains, "The freezing point of water increases with a
decrease in the pressure applied to it. Hence the freezing point of water
will be less at high altitude and low pressure. But this effect is small.
The freezing point of water rises a mere hundredth of a degree per
atmosphere of decrease in pressure."
That is, the difference is air pressure values between sea level and the
farthest upper reach of the Earth's atmosphere, say 500 miles aloft,
provides a freezing temperature increase of only 0.01 degree. For all
practical purposes, the freezing point remains unchanged.

Chicagoans will experience single-digit windchills today as gusty northwest winds usher in a cold Canadian-source high pressure air mass. The sun's impact will be diminished as it reflects off the fresh 2-to-5-inch snow cover in place after Saturday's storm. Winds will diminish Monday as the eastward-moving center of high pressure passes overhead.
By Tuesday, strengthening southerly flow will allow the return of milder air, but clouds will be increasing as low pressure develops in the central Plains and moves this way. Despite clouds and showers, Wednesday could well be the mildest day of the week as southerly winds continue.

SNOW MELTS OFF, THEN RETURNS
Winds shift to the northeast Thursday, but rain should continue, making it a cool damp day and removing any trace of snow cover. However colder air returns later Thursday night with rain changing to snow. Snow ends Friday with cold high pressure holding into the weekend.

Dear Tom,
You often mention "buckling jet streams," but that term confuses me. Could you please
amplify?
George Burger

Dear George,
Jet streams are belts of very strong winds found within a narrow depth in the atmosphere,
usually 6 to 9 miles aloft. Because these winds often steer the movement of surface air
masses and weather systems, weather forecasters pay them close attention. Jet streams
form in the boundary zones ("baroclinic zones") between warm and cold air. When masses
of warm and cold air relocate, jet streams buckle to conform to the new boundary's
position. It's a complicated process because pockets of wind maxima embedded within jet
streams often trigger the development of surface storm systems that, in turn, shift the
positions of warm and cold air, further distorting the jet stream. The process feeds on
itself.

The manner in which winter storms produce their snow is often more complex than it
appears to a casual observer. Take the storm in progress as Saturday dawns. The snowfall it
has generated overnight has been warm air advection snow. That's the snow which develops
as the storm's southerly winds force mild, moist air into cold air. Next comes the
storm's dynamically produced snow. That's the snow generated as upper winds exiting a powerful
jet stream wind pocket slow -- a process which also encourages snow formation. To anyone
watching from below, the snowflakes which result look exactly the same. Yet the storm
is producing its snow in very different ways. The third phase of many winter storms --
this one included -- is the lake-enhanced phase. This occurs in the final hours of a winter
storm as lake moisture is swept into its cold backside. Here, especially large flakes
form and, because of their enhanced size, are noticeably different than earlier snowflakes.
Snowfall may decrease or even ebb temporarily Saturday morning as a slot of dry air
common in winter storms shifts across the area. Snowfall resumes toward midday and through
the afternoon amid strengthening winds.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
How many times has Chicago had snow on the first day of spring (March 20 or
21)?
Bill Ooms, Alsip
Dear Bill,
Chicago winters are long enough and harsh enough to make us anxious for
spring, but don't be fooled. The beginning of spring comes so early that it
falls well within Chicago's normal snow season.
For people in the atmospheric sciences, spring (so-called meteorological
spring) begins on March 1. In Chicago, measurable snow has fallen on that
date in 24 of the 124 years since snow records began here in 1885 -- about
one year in five (one in 5.2). The greatest amount: 4.6 inches in 1947.
Astronomical spring, defined as the date of the vernal equinox, occurs on
either March 19, 20 or 21. Measurable snow has occurred here 22 times on the
vernal equinox, or one year in six (one in 5.6, actually). The biggest
storm: 6.0 inches on March 20, 1964.

Chicago's February snow drought is about to end. Indications remain compelling that a
swath of the Chicago area may be on the way to getting 6 inches or more of snow. Amounts
farther south -- from Morris to Kankakee and Rensselaer -- may be limited to several inches
because of an anticipated lull in snowfall for a time Saturday morning. The storm system
responsible isn't Chicago's conventional 6-inches + snow producer. Racing southeastward
from Canada, the system originates in a region of limited atmospheric moisture. But
computer models and an array of snowfall forecast techniques suggest it will compensate by
taking advantage of strong jet stream dynamics that will lift and cool available moisture to
produce clouds and snow. A modest injection of lake moisture appears a good bet
Saturday. The storm's snow accumulation is to be made up of 6-7 inches of "system snow" which
falls fairly steadily over 12 to 14 hours -- and a possible 2-3 inches of added lake
moisture which could boost totals in lakeside counties. Snow showers could linger into Saturday
night.
February is historically Chicago's third snowiest month, but has logged 0.8 inches. A
year ago, 14.8 inches had fallen to date.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Mr. Skilling,
What is the best and worst that can happen around here, snow-wise, in the winter?
Mildred Dudek

Dear Mildred,
A whopping 4,563.1 inches of snow have fallen on Chicago (excluding this winter)
since the inception of snow measurements in 1884. That averages to 36.8 inches per
winter but, as your question implies, snowfall varies greatly from year to year.

Oddly, the city's two least snowy winters and its two most snowy winters were each
back-to back affairs. The winters of 1920-21 and 1921-22 brought 9.8 and 11.5
inches, respectively; the snowiest winters, 1977-78 and 1978-79, put down 82.3 and
89.7 inches, respectively.

However, Chicago weather historian Frank Wachowski once remarked, "Weather records
are made to be broken," and the point is well taken. Chicago's snowfall records are not
carved in marble; it's only a matter of time -- those records will fall.

Carolyn Szepanski sent us this picture taken by her friend Mark Chryson who lives in Wasilla, Alaska. This picture was taken right outside his door!

Thanks for the picture Carolyn and Mark!

Photo courtesy of: Mark Chryson, Wasilla, Alaska

Travel was a nightmare Wednesday over sections of the area as snow combined with
plummeting temperatures to coat many thoroughfares from Rockford into Chicago's
west and northwest suburbs with ice. Conditions became so treacherous that a section
of Illinois Highway 25 in Carpen- tersville and a stretch of Randall Road in Geneva and
St. Charles had to be closed after a rash of accidents and spinouts. Snowfall reached
0.6 inches late Wednesday at O’Hare and Midway—the month's heaviest single-day
tally and the most significant snow since 1.9 inches on Jan. 28.

Until Wednesday, only 9 other Februaries over the past 124 years had produced so little
snow through mid-month. The snow drought didn’t last. Seven of those 9 Februaries
were followed by significant snowfalls (4 inches or more) before the snow season
ended. Typically a quarter (27%) of Chicago's seasonal snow falls after Feb. 19—and a
significant accumulation appears headed this way Friday night into Saturday.

SINGLE-DIGIT WINDCHILL THURSDAY

Thermometer readings struggle to escape the teens as gusty winds limit windchills to 4
degrees below zero to 6 degrees while delivering lake snow showers to portions of the
Indiana/Michigan snowbelt.

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

Dear Tom,
How far south in this country does subzero weather occur? Has it ever dropped below
zero in Texas or Florida?
Josh Sauerman Crown Point, Indiana

Dear Josh,
Florida has recorded a below zero temperature, but only once. On Feb. 13, 1899, with
an historic cold wave gripping the eastern half of the nation, the mercury dipped to
minus 2 degrees at Tallahassee. At the south end of the state, Miami's all-time low
temperature is 27 degrees and Key West's is 41.

Subzero weather does occur in Texas, especially in the north and in the higher
elevations of the west. The record low for the state of Texas is 23 below zero observed
at Seminole, located southwest of Lubbock near the New Mexico border at an altitude
of nearly 3300 feet. Farther south in Texas, the record low for San Antonio is zero,
recorded on Jan. 31, 1949.

Carolyn Szepanski sent us these pictures of Wednesday's snow.
Thanks Carolyn!

Wednesday opens with south winds blowing and Chicago in the "warm sector" of a
storm that swept 70s into Kansas and Oklahoma on Tuesday. That mild air in
combination with an influx of Gulf moisture and a fairly steep decline of temperatures
early Wednesday threatens to set the atmospheric stage for some thunderstorms. But
the warmth won't last long. Arctic air is on the move. A late season cold blast sends
temperatures diving Wednesday evening in what is to become the Chicago area's
coldest outbreak in two weeks—since 17 and zero-degree temperature extremes Feb. 4.
While longer days and more direct sunlight takes a bit of the edge off late winter cold
spells, Thursday’s chill is to be impressive. Daytime temperatures will be 15 degrees
below normal with single-digit wind chills.

ONLY 9 FEBRUARYS IN PAST 124 YEARS WITH SO LITTLE SNOW

Only modest snows are predicted as the cold air arrives Wednesday night. Some 1- to
2-inch totals aren't out of the question over portions of the area. More impressive
snow may occur Friday night into Saturday. Until then, February 2009 continues as one
of the nine least snowy to date in 124 years. Only 0.2 inches is on the books.

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

Dear Tom,
You have mentioned that salt particles in the air act as condensation nuclei for cloud
formation. Where does that salt come from?
Joseph Mathias

Dear Joseph,
Every cloud that passes overhead is a visible collection of myriad particles
consisting of water droplets or ice crystals or both; and every cloud particle began its
life as a so-called condensation nucleus on which water molecules collected. The
collection process is called condensation when the resulting cloud particle is a water
droplet and sublimation when the resulting particle is a tiny ice crystal.

Chief among condensation nuclei are specks of sea salt, even thousands of miles into
the interior of continents. Droplets of salty ocean spray, when they evaporate, leave
their tiny burdens of salt floating in the air, to be disbursed through the atmosphere
and around the world.

In a winter that more often than not has kept arctic outbreaks and snow coming,
February's weather has offered a bit of a reprieve. Not only has the month averaged temperatures
4 degrees above normal, it's running 4.5 degrees milder than the same period a year ago.
February snowfall has been a fraction of December's ( 21.9 inches) and January's (21.5
inches), totaling just 0.2 inches at O'Hare Airport. A normal February sees 8.3 inches of
snow -- more than 40 times this month's tally to date. But as any longtime Chicagoan will
tell you, winter snows are fickle. Nearly a third of Chicago's seasonal snow has fallen
beyond this date and forecasters are monitoring two systems for possible accumulations.
The storm responsible for 3-inch rains in California on Monday (a storm which prompted a
special marine warning in San Francisco Bay and brought 2 feet or more of snow to the
mountains surrounding Los Angeles) is the first under scrutiny. Forecasters are anxious to
see how computer projections of the system evolve once it moves into the land-based U.S.
weather balloon network. The system appears to have the potential to produce sticking
snow in Chicago later Wednesday. A second lake-enhanced snow could reach Chicago Friday
night into Saturday.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
What are the temperature ranges for it to snow?
Dennis Finn, Geneva, Ill.
Dear Dennis,
Snowflakes form in clouds only when in-cloud temperatures are below freezing (32
degrees). When in-cloud temperatures are above freezing, condensation produces water
droplets and rain. Usually, though, air temperatures at ground level are different --
sometimes higher, sometimes lower -- than temperatures in snow-producing clouds.

Chicago's biggest snowstorms generally occur with readings from about 25 to 32
degrees, but we have had snow with temperatures as high as the lower 40s and, on rare
occasions, below zero. Two inches of snow fell on Jan. 14, 2009, when the high/low
temperatures were 14 degrees and 2 below zero; nearly an inch of snow came down on
Jan. 10, 1982, with a temperature of 15 below zero. Snow routinely falls in Antarctica at
or below minus 50.

High pressure holds over Chicago today; but as it moves east Tuesday, winds strengthen
from the south and clouds increase rapidly from the west. Meanwhile, low pressure will
produce heavy snow in the southern Rockies then move into the central Plains on Tuesday.
That system is projected to intensify as the center of lowest pressure tracks through
northern Illinois on Wednesday. As a result, Chicago's temperatures will rise, probably warming
into the 40s despite the thickening and lowering cloud cover. Rain could begin Tuesday
afternoon, possibly becoming heavy at times as showers -- maybe thunder -- develop Tuesday
night and Wednesday morning. Wednesday looks to be very stormy from the Great Lakes to
the Gulf of Mexico, with heavy snow in Wisconsin and severe storms south of the Ohio
River. Chicago will experience falling afternoon temperatures as rain changes to wet, sticking
snow.
MUCH COLDER AFTER WEDNESDAY
Chicago temperatures will stay below freezing Thursday to Sunday as cold Canadian-source
high pressure is reinforced after a second snow-producing low pressure Friday.
--By Paul Dailey, WGN Weather Center Meteorologist

Dear Tom,
Ducks are often seen in lakes (fresh water) when Chicago's temperatures are
below zero. The 32-degree water must seem warm to them. When it is 40 below
in polar climates, how "warm" would the sea water be to the penguins?
Shawn Groom, Palatine
Dear Shawn,
Pure water freezes at 32 degrees. Water molecules, which tumble about
loosely when in the liquid state, become ordered in a crystalline lattice
during the freezing process. (By the way, the lattice structure encloses a
bit of space; that's why water "expands" when it freezes into ice.) However,
foreign particles in water (such as sodium and chlorine ions from dissolved
salt) hinder the formation of the crystalline structures because they
interfere with intermolecular forces between the water molecules. The result
is that the freezing temperature of salt water drops, sometimes into the
middle 20s.

Our astronomy consultant Dan Joyce, astronomer at Triton College's Cernan Space Center has passed on three more spectacular photos taken out in the northwest corner of Illinois just south of Elizabeth in Jo Daviess County.

This photo was shot with an 8" telescope is IC1871, also known as the "Heart and Soul Nebula" in Cassiopeia, probably just over 2,000 light-years away.

This photo, taken with a 10" scope depicts IC 405 also known as the "Flaming Star Nebula" in Auriga and is about 1,600 light-years out. The bright star varies its radiant output but averages 950 times the solar luminosity. The reddish color is hydrogen fluorescing in the star's ultraviolet radiation and the bluish-purple is a reflection of the star's own color mixed with the glowing hydrogen.

The last photo is galaxy IC 342 (it has no fancy name) and is about 11,000,000 light-years away in the obsure northern constellation of Camelopardalis. This shot was taken with an 8" telescope.

The week ahead in Chicago will start and end on a cold note -- a sign that winter is not
yet ready to relinquish its icy grip on the city.
After a week of bare ground, a light snow covered the area Saturday. The ground should
remain at least partially snow-covered into Tuesday before temperatures surge into the
40s, triggering a rapid departure of any remaining snow.
MIDWEEK STORM SYSTEM TO START RAINY BUT END SNOWY
That warmth will arrive ahead of a vigorous storm system slated to pass south of the
city through central Illinois. The storm will start out as a rain producer Tuesday night,
but as colder air feeds back into the city on gusty northeast winds on the system's western
flank, the precipitation should quickly change to snow on Wednesday. Several inches of
snow could accumulate before diminishing to flurries late in the day.
The rest of the week will take on a wintry feel with highs in the 20s and 30s. Some snow
is possible as a weather disturbance moves through the area Friday night and Saturday
and more lake-effect snow will occur in the Michigan and Indiana snowbelts.
--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
Last Tuesday, we just missed breaking a record high that stood since 1876. What are
Chicago's longest-standing temperature records?
-Ken Kapson, Chicago

Dear Ken,
According to Chicago climatologist Frank Wachowski, the city's longest standing
temperature records are back-to-back lows set Dec. 4 (6 degrees below zero) and Dec.
5 (minus 8), 1871, just about a year after the city's climate records launched in late
1870. Chicago's longest-standing record highs date back to Dec. 31, 1875 (a balmy 68)
and the following day when it reached 65. The Feb. 10, 1876, record high of 63 that we
fell just short of last week is the city's third-oldest record high on the books.
Wachowski also noted that a 62-degree record high on Jan. 12, 1871, has never been
surpassed, but because it was tied on Jan. 12, 1890, the later date is the one in the
record book.

The ground is covered with snow for first time in a week. Only a week ago, readings were
headed to near 60 degrees here -- a development which brought an unceremonious end to
the longest-lasting winter snow cover in eight years. For 32 consecutive days, an inch or
more of snow covered the ground. The storm system responsible for Chicago's overnight
snows walloped sections of Nebraska and Iowa on Friday. Nebraska totals included 10 inches
at North Platte and Calloway and 8 inches at Omaha, while 7.1 inches fell at Des Moines.
Though the system was weakening as it swept toward Chicago, it generated 3 inches of snow
near Freeport and 2 inches in Rockford by late Friday evening, producing numerous
accidents.
Until Friday, this month's lack of measurable snow during its opening 12 days in Chicago
was in stark contrast to the 14.5 inches that fell during a comparable February period a
year ago.
Cold north winds travel down Lake Michigan late Saturday night into early Monday and
threaten to provoke lake-effect snow showers in the Indiana snowbelt. A few flurries may
even swipe the northeast Illinois shoreline. A stronger storm is being monitored Tuesday
night into Wednesday.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
In my astronomy class I learned that century years were not supposed to have
a leap day. Why then did February 2000 have 29 days?
Marlene Fisher, Blanchard, Mich.
Dear Marlene,
Most people are familiar with the fact the leap years occur in years that
are divisible by four. However, if a year is divisible by 100 (century
years) it is not a leap year unless it is also divisible by 400. That is why
1700, 1800 and 1900 were not leap years, but 2000 was. There will not be a
leap day in 2100, 2200 and 2300 but there will be one in 2400, the next
century year to have a Feb. 29. Leap days are needed to keep the calendar in
sync with the seasons.
A tropical year, defined as the time between successive vernal equinoxes, is
365.2422 days -- so adding a leap day every four years keeps the alignment
differences between the calendar and the seasons fairly insignificant.

Thanks to retired Chicago Tribune/WGN employee Daniel Kowalec now living at Mescal, Arizona-about 45 miles east of Tucson for passing on these shots showing the 4 inches of snow that fell there. Pictured is the snow-covered Rincon mountain range east of Tuscon. Dan reports that the snow was great for making snowballs and snowmen.

--WGN-TV Weather Center

Chicago's first measurable snow in more than two weeks may whiten the ground in time for
Valentine's Day (Saturday). It's true that Indiana's snowbelt was lambasted by one of
the biggest lake snows in decades in February's opening days, but that snow bypassed
Chicago. Not since Jan. 28, when 1.9 inches fell at O'Hare International Airport, has a
measurable snow (0.1 inch or more) occurred in the city. It's been 11 years since a February has
reached its 13th day with so little monthly snow on the books.
The incoming snow is being handled inconsistently by computer models -- not unusual in
developing weather situations. But, an average of all model predictions of this system in
recent days suggests as much as 2 to 4 inches of snow may fall here over a 6- to 10-hour
period beginning late Friday. Several lake effect flurries may precede that snow as early
as Friday afternoon. Winds may become favorable for additional lake-effect snow Sunday
into Monday.
WINTER'S 'COLD RANKING' SLIPS
Recent mild temperatures have slashed Chicago's winter temperature ranking from 10th to
20th coldest. Readings since Dec. 1 have averaged 20.9 degrees -- 5.3 degrees below
average and 4.9 degrees colder than a year ago.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
What kind of weather does the moon have?
Kenny Birks (age 10)

Dear Kenny,
The moon has no weather at all -- and that sounds pretty bleak, don't you think? The
kinds of events that come to mind when we think about "the weather" -- wind, clouds,
precipitation (like rain, snow, sleet and hail) and storms of all kinds (such as
thunderstorms, tornadoes and hurricanes) -- all those phenomena are children of the
Earth's atmosphere.

Our language is sprinkled with words that we commonly use to describe the weather --
hot, warm, cool, cold, humid, rainy, cloudy and fair, to name a few. You can probably
think of many more, but all of them would be useless if you were on the moon because
the moon has no atmosphere, none at all, and so it has no weather. The moon's gravity
is so weak that it cannot keep gases like the kinds that make up our air from escaping
into space.

Our friend pilot Anson Mount shares these photos he took Thursday while 6,000 ft.
above Pontiac on a flight to Springfield in downstate Illinois. In his e-mail
accompanying the photos, he reports,

"The soil is saturated as you can see by all of the standing water."

Anson's photos included some wonderful airborne shots of crepuscular rays. THANKS for sharing these, Anson!

Tom Skilling

Photos courtesy of Anson Mount, Algonquin, Illinois

Downpours Wednesday, the heaviest here since thunderstorms swamped the area with nearly
2 inches of rain Dec. 27, set a record at O'Hare. The 0.83 inches there blew past the
previous Feb. 11 record of 0.70 inches recorded 129 years ago. Other area totals included
1.23 inches at Valparaiso, Ind., 1.08 inches at Romeoville, 0.85 inches at St. Charles and
0.78 inches at Oak Brook. Downstate Illinois bore the brunt of Wednesday's storm. There,
t-storms erupted near Homer in Champaign County producing 60 m.p.h. wind gusts. Rains in
the region were heavy and included 4.11 inches at Hidalgo, 4.00 inches at Effingham and
3.10 inches at Vandalia.
Sunshine's return Thursday and Friday belies the development of a stormier, more wintry
pattern which may dominate the U.S. much of the remainder of February. A series of storms
embedded within a powerful jet stream roaring off the Pacific are likely to traverse the
U.S. at 3- to 4-day intervals. Among them is a system expected to affect Chicago with
potentially accumulating snow Friday night into Saturday. An average of 38 computer
forecasts suggests as much as 6 inches of snow could render bare ground history here by the
weekend. Lake snow showers may linger into Sunday.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Why can I hear airplanes and other far-away sounds so much better the colder it gets
outside?
Mark Barberis
Dear Mark,
Distant sounds can be heard more clearly in frigidly cold air than in warm air. Because
outdoor activity is reduced and fewer people are stirring about when it is very cold,
individual sounds are easier to distinguish.
The most important factor, though, is the great difference in the thermal structure of
the lower atmosphere when it is cold versus when it is hot. When air temperatures
change along the path that sound waves are traveling, the waves always bend toward
the colder air. In bitterly cold arctic air masses, the coldest temperatures are at the
ground with higher temperatures above; sound waves do not disburse upward readily.
On hot days, it's just the opposite: It's hottest at the ground and cooler above; sound
waves bend up and away.

It was great while it lasted, but Tuesday's wind-blown 60 degree warmth has vanished as
the city braces for today's heavy rain episode followed by cold and snow in time for
Valentine's Day. Tuesday's balmy highs broke the 60 mark for the first time in 2009. Midway
Airport's 62 degree maximum was the warmest ever there on a Feb. 10, eclipsing the pair of
61 degrees highs reached in 1976 and again in 1999, while the city's official
thermometer at O'Hare International Airport peaked at 61 -- just shy of the record 63 degree high
set in 1876.
Severe weather struck Oklahoma on Tuesday afternoon, producing three damaging twisters
along with highs winds and large hail. One twister did considerable damage in Edmond,
just northwest of Oklahoma City. This same storm system is going to bring heavy rain and
possible flooding to the Chicago area Wednesday as up to 2 inches of rain falls on rivers
swollen by the recent snow and ice melt.
A second storm is expected to bring accumulating snow to the city by late Friday. Early
trends indicate that 3-5 inches could be on the ground here by Valentine's Day.
--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
Why is Aurora always colder than everywhere else?
Chad D. May
Assistant Principal/Athletic Director
Lake Zurich Middle School South
Lake Zurich, Ill.

Dear Chad,
Jim Allsopp, Warning Coordination Meteorologist at the Chicago office of the
National Weather Service, explains: "The weather observation is taken at the
Aurora Airport which is actually in Sugar Grove, about eight miles west of
downtown Aurora. It is a rural setting and it is not representative of
temperatures in the city of Aurora.
"The airport sits in a low spot. On nights with conditions favorable for
strong radiational cooling -- clear skies, light winds -- cold air, because
it is more dense, settles in low spots and valleys. The Sugar Grove weather
equipment is regularly maintained and calibrated by NWS technicians and it
is in good working order."
The Sugar Grove weather observations provide necessary information for
aviation operations and are not intended for other purposes.

A day of record-breaking warmth -- potentially 2009's mildest to date -- sweeps into
the area Tuesday, the product of powerful winds and generous sunshine. Wind trajectories,
which allow the tracking of air mass movement produced by winds, indicate the May-level
60s predicted here had origins not more than 24 hour ago in Louisiana, Arkansas and
Missouri. Record highs Monday -- including 66 degrees Downstate in Springfield, 72 at Paducah
and 70 at Louisville -- occurred within this air mass. Not since a 71-degree high here
three months ago, on Nov. 5, has the Chicago area been treated to warmer temperatures.
There had been two days of 60s by Feb. 10 a year ago, but temperatures of 60 degrees or
warmer this early in the season have occurred in only one of four years since local
weather records began in 1871.
The same storm producing Tuesday's warm winds has coated the Upper Midwest and Plains
with ice and snow. A second storm, responsible for a rare tornado near near Atwater,
Calif., on Monday and for big snows in the mountains of the West -- including 20 inches at
Alpine Meadow Ski resort in California -- next targets the Mid- west late Tuesday night and
Wednesday.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
What is the latest date we've ever had a temperature below zero?
Deborah Morgan, Batavia, Ill.
Dear Deborah,
Winter is winter and low temperatures are to be expected, but the frequency of frigid
weather this winter is testing the patience of even normally stoic Chicagoans. We're
beginning to hear questions like yours -- variations on "How much longer can this
last?" The answer, based on a computer scan of Chicago's temperature history, is: Quite
a bit longer. A sub-zero reading has been recorded here as late March 22, when the
city's temperature hit 1 degree below zero. Needless to say, that was an extreme event,
but temperatures this winter have tended toward the extreme. With an average
temperature of 19.3 degrees, the December-January period entered Chicago's record
books as the city's 10th coldest, and the coldest in 26 years.

Low pressure approaching from the west is expected to spread a brief period of showers
over northeast Illinois this afternoon and tonight. As this band of rain moves to the
east, southwesterly winds will pick up, pulling unseasonably warm air into the area Tuesday.
Chicago's 63-degree record high for Feb. 10 that has stood for 133 years will be tested.
The mild air will also threaten the record high minimum temperature of 43 set in 1886.
Because warm air holds more moisture, showers and thunderstorms could dump heavy rain
before low pressure and the associated cold front Wednesday. Computer models indicate that
as much as 2 inches of rain could fall with these storms, resulting in heavy runoff over
frozen soil and subsequent flooding of already swollen rivers and streams.
TURNING COLDER THURSDAY
For the rest of the week, colder Canadian high pressure will hold over the northern half
of the country, including northern Illinois. This will force low-pressure systems to
track east through the southern portions of the United States and keep Chicago mostly
precipitation-free.
--By Paul Dailey, WGN Weather Center Meteorologist

Dear Tom,
The polar regions experience very short days in the winter, but the tropics
still have long days. The question is, do the polar regions receive as much
sun as the tropics? I would think not.
Martin Eck
Dear Martin,
We posed your question to astronomer Dan Joyce of the Cernan Earth and Space
Center at Triton College, and he provides this uncharacteristically brief
answer, "This is going to kill me, given my propensity for the long haul,
but, in a word, the answer is 'yes!'"
And that says it all. Cloudiness aside, long summer days and short winter
days in the Earth's polar regions offset each other, thereby exactly
preserving the annual average of six months of daylight and six months of
darkness. And that is also true everywhere else on the planet -- in the mid
latitudes (Chicago's location), in the tropics and at the Equator, and at
the North and South Poles.

The city's snowpack, which has covered the ground for more than a month, all but vanished Saturday as the mercury soared into the 50s, bringing the warmest weather here since late December. O’Hare reached 56 degrees and Midway 59, but strong southwest winds sent the mercury to 61 degrees along the lakefront at Northerly Island.The city's official thermometer at O'Hare reached 56 degrees falling short of the day's official record high of 59 set back in 1925, but Midway observer Frank Wachowski tells us that Midway Airport peaked at a balmy 59 degrees establishing a new record high for that site, eclipsing the old record of 53 set in 1965 and tied in 1987. Records tumbled elsewhere around the state including Peoria (65), Springfield (67), Rockford (52) and St. Louis (70).
Cooler weather will return Monday with readings only reaching the lower 40s, but temps rebound sharply on Tuesday as gusty southwest winds should have the city flirting with 60 degrees. The warmth will be followed by some heavy rainfall and even some thunderstorms Wednesday, which combined with added moisture from the melting snow and ice could result in flooding on area streams and rivers.

WINTER RETURNS BY WEEK'S END
Colder air will flood into the region in the wake of the storm, setting the stage for more snow as a series of storm systems parade through the southern states. The first of these could arrive Saturday, making for a snowy Valentine's Day.

--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
Has every one of the 50 states recorded a temperature of 100 degrees or higher?
Rev.Ray Cosentino, Homer Glen

DearRay,
Yes, all 50 states have reached the century mark, but our two newest states barely made
the cut. The only time Alaska reached triple digits wason June 27, 1915, with a high of
100 degrees at Ft. Yukon. Pahala, on the Big Island of Hawaii, holds the honors for that
state’s hottest day with a 100-degree high on April 27, 1931. With the exception of New
England, where the all-time state highs hover around 105, the rest of the country’s
highest readings have topped 110 degrees. Illinois’ hottest is117 degrees set at East St.
Louis on July 14, 1954. The nation’s hottest reading, a blazing 134 degrees, was recorded
at Greenland Ranch in Death Valley, Calif., on July 10, 1913.

Friday's 41 degrees marked the first time in 2009 that winter-weary Chicagoans have
been treated to an official reading above 40. After the battering Chicagoans have endured
through a parade of arctic air masses responsible for the 9th coldest and 6th snowiest
winter to date of the past 138 years, a day above freezing has become a cause for
celebration. Temperatures have risen slowly overnight and soar 11 degrees higher than Friday this
afternoon, reaching 52 degrees. The reading comes almost six weeks since city was last
treated to a 50-plus-degree high. Melting on Friday reduced Chicago's snowpack 1 inch, to a
depth of just 4 inches, and will end up completely obliterating the 33-day-old snowpack
in coming days. The incoming warmth has origins in the Plains where record-breaking
June-level 80s occurred in Kansas. Garden City's 81 degrees not only set a record, it blasted
past the previous record of 66 set in 1984 by 15 degrees.
WINTRY PATTERN TO RETURN
An often stormy, colder than normal weather regime takes hold after Wednesday and
dominates the remainder of the next two weeks. Typically, 38 percent of Chicago's snow falls
beyond this date.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
My dad claims Chicago had a winter in the late 1970s in which it did not
snow from Feb. 1 forward. Given the heavy snows we had in the winters of the
late 1970s, I am skeptical. Is my dad correct?
Tom Shute
Dear Tom,
Your dad is incorrect. Winter is still going strong in February, and it's
asking a lot for the entire month to be snowless. Even March, with rapidly
warming temperatures, is often a snowy month. Together, they have produced
at least some snow from Feb. 1 onward in every winter since records began
here in 1884.
But let's not be too harsh. In all likelihood, your dad was recalling the
bitterly cold and record-snowy winter of 1978-79. By Feb. 1, 79 inches of
snow had buried Chicago, and it was widely speculated the winter total would
top 100 inches. However, the pace of snow abruptly diminished, and the
season ended with "only" 89.7 inches.

Friday marks the 32nd consecutive day Chicago-area residents have looked at snow covered
ground. It's the longest stretch of snow cover here in 8 years -- and one which is about
to end. Dramatic warming, which sent Plains temperatures as far north as Nebraska
soaring into the 60s on Thursday, is making its move on Chicago. Modest warming sent highs here
to 25 degrees Thursday -- up from 17 the day before. Readings jump another 15 degrees
Friday to 40. But, it's Friday night and Saturday that the most substantial warming is to
get under way. South winds from the Gulf of Mexico increase by Saturday morning to 80
m.p.h at 3,000 feet above the ground here. The set-up is to generate 30+ m.p.h. surface gusts
by late Friday night. As moist air reaches the metro area late Friday the lower
atmosphere will become saturated. Clouds, fog and drizzle will develop quickly. With dew points
-- the temperature at which the humidity is 100 percent -- predicted to rise into the low
40s over the cold, snow-covered surface during the night, the potential for thick fog is
real.
The rapid warming threatens ice jams on area rivers as the run-off from melting snow
hits. It's a formula for river flooding.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
The lowest temperature so far this winter has been 18 degrees below zero. That seems
colder than we usually get in the winter here in Chicago. How many winters have had a
lower temperature than 18 below?
Paul Rubin

Dear Paul,
Your hunch is correct. A computer scan of Chicago's entire official temperature data set
(138 years of records from the winter of 1870-71 to the present) reveals that only 12
winters have produced a reading lower than the temperature of 18 degrees below zero
recorded here on Jan. 16. And that was the city's lowest temperature in 13 years --
since 19 below zero on Feb. 3, 1996.

On average, the coldest temperature recorded during the winter at O'Hare Airport is 11
degrees below zero. Over the last ten years, however, with relatively mild winters, the
lowest temperatures each winter have averaged only 6 below zero.

Stunning photos taken by former Chicagoan, Colleen Baker, around 12:30 Thursday
afternoon in Lakeland, Florida. Early morning temperatures there dipped to a frigid
27-degrees while her sprinkler system was running. This resulted in a thick layer of ice
coating trees, shrubs and even her patio table.

Thanks much Colleen for sharing these with us!
-Bill Snyder---WGN Weather Producer

Photos courtesy of Colleen Baker, Lakeland, Fla.

Jaclyn Janoski sent us these pictures of the lake-effect snow which buried Michigan City!

Photos courtesy of Jaclyn Janoski

Here are some pictures sent to us by Gayle Beschinski from Chesterton, Indiana.
Thanks for the shot's Gayle!

Photo courtesy of Gayle Beschinski

The final flurries of this week's crippling 30-hour Indiana lake-snow storm fluttered
to earth late Wednesday after burying sections of Porter and La Porte Counties under as
much as 2 1/2 feet of snow. By sunset Wednesday, Burdick -- 5 miles east of Chesterton --
had taken on the dubious distinction as the storm's hardest hit community, reporting an
accumulation of 29 inches. That's nearly 80 percent of Chicago's average full-season snow
tally. Dr. Craig Clark, meteorology professor at Valparaiso University and widely regarded
as the department's winter weather and lake-snow expert, minces no words. He reported
the storm's nearly 2 feet of snow in Valparaiso made it that community's heaviest
lake-effect snow since December 1981.
Thursday is the season's 12th morning of zero or lower temperatures at O'Hare, which
makes this cold season the most prolific zero-degree producer in 25 years. This comes as the
metro area enters its 31st consecutive day under an inch or more of snow. Warming in
coming days -- a slow process at first -- leads to a 50-degree temperature increase by
Saturday afternoon. The day may produce the first 50-degree high here since late December.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
My husband is still upset with me for not picking him up after work on
Valentine's Day 1990. Can you remind him why I didn't?
Fran Fredricks, North Aurora
Dear Fran,
You were smart to stay home that evening. Valentine's Day 1990 left a legacy
of undelivered flowers and canceled dinners as a major snowstorm brought
Chicago to a standstill. Snow began shortly after noon and quickly became
heavy with visibilities dropping to near zero. The storm reached peak
intensity during the evening rush hour as strong northeast winds gusting to
more than 30 m.p.h. piled the heavy snow into huge drifts. Snow-clogged
streets were littered with abandoned cars. The storm raged through the early
morning hours of Feb. 15, blanketing the area with 8-12 inches of snow.
Downstate, the storm produced freezing rain and sleet that encased much of
central Illinois in ice.

Here are more great pictures from the remarkable lake-effect snow event that hammered Northwest Indiana yesterday and today. Please keep these wonderful pictures coming!
—WGN-TV Weather Center

Photos courtesy of James Flis, Valparaiso

Photos courtesy of Dennis Rock, Valparaiso

Photo courtesy of Joe Scida, Valparaiso

It was a nightmare scenario for Indiana snowbelt residents Tuesday afternoon and
evening. Lake-effect snow, fluffy by its nature, began falling late Tuesday morning and was
soon airborne in the day's powerful 30-plus m.p.h. gusts. Snowfall became heavy so quickly
that visibilities in Valparaiso -- 50 miles southeast of Chicago's Loop -- had plunged to
less than a quarter mile within an hour of its onset and remained there the rest of the
afternoon. Many areas of Lake, Porter, western La Porte and Starke Counties in northwest
Indiana reported travel-crippling whiteout conditions. Snowfall rates of 3.5 to 4 inches
per hour rivaled the heaviest snows that have fallen in Chicago. By late evening, 12.5
inches had accumulated in San Pierre in Starke County. Other early storm totals included 9
inches at Valparaiso, 7 inches at Michigan City and 6.5 inches north of La Porte -- and
snow was still coming down and expected to accumulate further into Wednesday. Final snow
accumulations could reach or exceed 20 inches in the hardest-hit areas of northwest
Indiana, and widespread totals of 6 to 12 inches were predicted by the time the snow finally
ends late Wednesday.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
I saw that January 2009 was the 10th coldest January in Chicago history, but
where does it rank among Chicago's all-time coldest months?
Derek Bogdan, Chicago
Dear Derek,
A computer scan of Chicago's entire temperature data set from Nov. 1, 1870,
to the present -- a period comprised of 1,659 months -- identified the
city's coldest 20 months. Sixteen of the "bottom 20" were Januarys. No
surprise there, because January is the core of the cold season and, in any
given winter, it's usually the coldest month.
January 2009 was, as you noted, the 10th coldest January on record with an
average temperature of 15.9 degrees. But when the ranking includes all
winter months, it drops to the city's 13th coldest month. Nine Januarys were
colder, as was December of 1983 (14.3 degrees), February of 1875 (14.6
degrees) and February of 1936 (15.3 degrees).

These dramatic snowy photos were taken Tuesday afternoon by our former intern Aaron Brackett on the campus of Valparaiso University. Visibilities at times dipped to near zero amid the wind-whipped heavy snow as gusts approached 40 m.p.h. As of late Tuesday evening, 9 inches was reported from the lake-effect snow event—and more was to fall.
--By Bill Snyder, WGN-TV Weather Producer

Photos courtesy of Aaron Brackett

Here's a look at the near whiteout conditions in Chesterton, Ind. at 2:30 p.m. Tuesday, Feb. 3:

Photo courtesy of Richard Vasquez

Here's a look at conditions in Valparaiso, Ind. at 3:20 p.m. Tuesday, Feb. 3:

Photo courtesy of Kathy Pasley

Lake-effect snow in Valparaiso on Tuesday afternoon.

Photo courtesy of Allan McLean, Arlington Heights

Dave Hartke of Channahon shares this photo of a robin -- one of about 20 he and his daughter spotted Sunday, Feb. 1, while walking along the Illinois & Michigan Canal State Trail in Channahon. Dave commented:

"I was very surprised to see them so early especially with all the snow cover. I assume they flew in on the two days of warm southerly winds."

Seeing robins during the winter isn't as unusual as you might guess (read Tom's Ask Tom Why about this topic).

Thanks Dave for sharing your photo!
—WGN-TV Weather Center

Photo courtesy of Dave Hartke, Channahon, Ill.

The meteorologically explosive combination of bitterly cold arctic air interacting with
"warmer" lake waters sets the stage for significant lake snow in portions of the Chicago
area Tuesday and Tuesday night. Moisture-laden air hugging Lake Michigan becomes buoyant
in this environment, fostering snow cloud development. The situation threatens to become
a prolific snow producer as north/northeast winds set up the length of the lake and
channel concentrated snowfall ashore. Snowfall will come and go with increasing frequency as
that band oscillates back and forth across eastern Lake, Cook and Will Counties in
Illinois and Indiana's Lake and Porter Counties. Snowfall is likely to be minimal in the western
suburbs that are out of reach of the lake snow. The potential exists for 2 to 4 inches
of snow, with 6 inches in spots, accumulating Tuesday and Tuesday night near the lake.
The heaviest snows shift into Indiana and continue into Wednesday; the extended duration
could produce 6- to 12-inch totals.
The last time the city saw bare ground was Jan. 5 -- 29 days ago. It's the longest
streak since the 63 days that 1 inch or more covered the ground from Dec. 6, 2000, through
Feb. 6, 2001.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune

Dear Tom,
Feb. 3 marks the 50th anniversary of the plane crash that killed Buddy
Holly, the Big Bopper and Ritchie Valens, and I read that the crash was
weather related. Can you provide any details?
Keith Mullen
Dear Keith,
The plane carrying the three rock stars took off from Mason City, Iowa,
around
1 a.m. on Feb. 3, 1959. Temperatures were around 20 degrees, and light snow
was falling. Weather reports indicated poor visibility as well as icing and
turbulence in the clouds. The pilot was not adequately advised of the
deteriorating weather conditions. In total darkness with snow falling and a
snow-covered landscape, the pilot lost the horizon and was forced to rely on
instrumentation he was not familiar with. The plane slammed into the ground
shortly after takeoff, killing all on board.

Janet Cameron was kind enough to share this wonderful photo of an unidentified man feeding geese at Montrose Harbor on Sunday, Feb. 2. Thanks Janet!
—WGN-TV Weather Center

Photo courtesy of Janet Cameron

The Chicago area, locked in a non-stop wintry pattern that brought its 10th coldest
January on record, is finally going to get a break from the cold and snow later this week.
Milder weather will sweep into the area by the weekend, putting a dent in the area's
persistent deep snowpack.
However, before that occurs, the city is facing yet another blitz of snow and cold.
Colder air and some snow will flow into the Midwest late Monday courtesy of strong northerly
winds as low pressure moves into lower Michigan. The trajectory will take arctic air down
the length of Lake Michigan, enhancing the precipitation with lake-effect snow, first in
northeast Illinois and then to northwest Indiana as winds back northwest, bringing
several inches of accumulation. When skies finally clear late Tuesday, readings will plunge --
bringing another night of zero weather to inland areas.
QUICK REBOUND IN TEMPS TO BRING 40s
By Thursday, southwest winds will bring milder air, sending readings Friday to 40
degrees for the first time in 2009. In addition, a weekend rain will help wash away much of the
ice and snow. More rain could arrive early next week.
--By Steve Kahn, WGN Weather Center Meteorologist

Dear Tom,
A recent question dealt with brutally cold back-to-back weekends in January
1982. Weren't all four Sundays that month extremely cold? Was that our
coldest month ever?
Malcolm Vye
Dear Malcolm,
January 1982 averaged a frigid 12.2 degrees and ranks as the city's fourth
coldest month on record. The only colder months here have been January 1977
(10.1 degrees), January 1912 (11.9 degrees), and January 1893 (12.0
degrees). Actually, January 1982 had five Sundays, and three of them
registered subzero readings. The first Sunday, Jan. 3, was relatively mild
with a high of 35 and a low of 30. The 10th and 17th were extremely cold
with high/lows of minus 4/minus 26 and 4/minus 23 respectively. Jan. 24 was
the third straight subzero Sunday with a high/low of 3/minus 3. The month
ended on a slightly milder note with a high/low of 21 and 10 on Jan. 31.