One of the wettest and cloudiest Octobers ever in Chicago is in the record books. The 7.69-inch rainfall measured at Midway Airport was the fourth wettest since observations began there in 1928. O'Hare International Airport is Chicago's official observation site, and its total of 6.04 inches was the ninth greatest in the 139 years of city records dating back to 1871. Rainfall frequency was also extraordinary, with measurable rain (0.01 inches or more) occurring on 19 of the 31 days, which tied October's all-time record set in 1883. Illinois State Climatologist Jim Angel noted that even greater rainfall downstate raised the state average to 8.35 inches---the second wettest since cumulative state records were begun in 1895 (9.23 inches in 1941 is the wettest on record.)
Chicago's October's sunshine was only 33 percent of possible sun (58 percent is normal)--the second-cloudiest on record dating back to 1893. It actually tied two other years (1917 and 1984.) Only the 31 percent in October 1925 had less sunshine. Chicago's October temperatures also averaged about 5 degrees below normal.
Early November outlook
Chicago temperatures are expected to average slightly below normal through Wednesday, but there are indications of a warming trend. The Climate Prediction Center's 6 to 10-day and 8 to 14-day outlooks call for area temperatures to average slightly above normal, and precipitation to be well below normal (good news for area farmers!).
Dear Tom,
With November beginning, I'm wondering what the month's weather extremes are in Chicago.
--Tarleton Edwards Dear Tarleton,
Dear Tarleton,
November weather in Chicago transitions from autumn to winter, sometimes gradually but often harshly and abruptly. Normal high temperatures decline more rapidly than in any other month --on average 1 degree every other day (from 55 degrees to 40). At its extremes, November weather displays a split personality. The month's highest temperature, 81 degrees (recorded on Nov. 1, 1950), and its lowest temperature, 2 degrees below zero (Nov. 24, 1950), occurred only 23 days apart. November usually brings the season's first accumulating snow, and the average monthly snowfall is 2.2 inches --- but 14.8 inches came down in November 1940.
It's an October responsible for unusual weather which we'll not soon forget once it closes at midnight Saturday. Rain has fallen more frequently than in any October since 1925 -- on 22 days since the first of the month, 19 of them measurably.
Midway Airport's eye-catching 7.69" October total -- which includes Thursday night and Friday's 2.26" downpours -- finishes nearly three times "normal." The month's gray skies have permitted only 33% of October's possible sunshine -- a far cry from the 58% which is normal -- and the least October sun here over the past quarter century. It's among the three lowest October sun tallies since 1893. And if the wet, gray weather hasn't been enough, October's 48.9-degree average temperature comes in at 5 degrees below the long-term average, making it the 19th coolest in 139 years. It's estimated home heating may have been up as much as 21 percent over a year ago.
The wind-driven deluge Thursday and Friday -- the 2nd to drench the area in a week -- produced eye-catching totals. Early measurements from Weather Bug rain gauges ranged as high as high as 3.65" at Hebron and 3.54" at Darien. Chesterton picked up 2.74" and Kankakee County's Bonfield was swamped by 2.55" while National Weather Service CO-OP observers reported 3.10" at Portage, Ind.; 2.50" at Woodridge; 2.39" at Romeoville; and 2.26" at Oak Brook and Peotone.
State Climatologist Dr. Jim Angel of the Midwestern Regional Climate Center reports statewide rainfall in October will finish 2nd wettest since 1895. It's the wettest to occur in Illinois since 1941.
Friday's 67 degrees not enough; October the first in 92 years not to generate a 70-degree high
While temperatures and surging humidities (dew points, a measure of atmospheric moisture, surged into the mid 60s) produced a springlike feel to the air Friday and highs of 67 degrees at O'Hare and 68 degrees at Midway, the month closes at midnight as the first October in 92 years which has failed to produce a single 70-degree high. That's happened in only two Octobers over the 139-year Chicago weather record. Temperatures did reach 70 Friday at Gary!
Dear Tom,
The first day of winter is Dec. 21, the shortest day of the year. Days start lengthening after that and the Earth also gets closer to the sun. So why does Chicago continue to get colder almost to February?
Bob Thurston
Dear Bob,
The sun is 2.8 million miles closer to Earth in early January than it is at its most distant point in early July. However, the effect of that "closeness" is overwhelmed by the effect of the tilt of our planet's axis relative to the sun. That tilt situates the Northern Hemisphere away from the sun's most direct rays, thereby reducing the amount of solar energy available for heating.
Other cooling factors such as round-the-clock darkness and widespread snow cover in the polar north prove far more important in determining temperature than closeness to the sun, and cold air continues to expand its dominance well into January.
For the second time in a week, the area is being walloped by significant rains. The October rain tally had reached 4.63" at O'Hare and 5.46" at Midway even before the current system's precipitation began Thursday, assuring the month a spot among the Top 10 wettest Octobers on the books here. The frequency with which rain has fallen the past 30 days has been stunning. The last time an October produced 22 days with a trace or more of rain occurred 84 years ago in 1925.
The waves of rainfall predicted to sweep the Chicago area Friday are a continuation of overnight downpours, some from 41,000-foot thunderstorms. They fall on saturated soils unable to absorb them. With no option but to run-off, the 1" to local 2.5" totals predicted by Friday evening will stream into area rivers threatening flooding. The Fox River near Montgomery was within 0.2 feet of flood stage even before the latest deluges arrived.
The powerful autumn storm behind Friday's downpours has established an uninterrupted flow of Gulf moisture riding 60-plus mph south winds into the Midwest just above the surface. It's a set-up which assures a nearly limitless supply of moisture to fuel Friday's waves of gusty showers and thunderstorms. Though rain won't fall continuously, when it does it may well be heavy. With dew points, a measure of atmospheric moisture, predicted to hover around 60 degrees Friday -- much higher than yesterday's upper 40s -- in combination with mild south rather than lake-cooled southeast winds, Friday should feel "warmer."
Chicago's wet storm was responsible for a half dozen twisters which dipped Thursday from Texas, Louisiana and Arkansas skies. Rainfall topped 5" near Shreveport, La., and flood watches extend over a dozen states from the Gulf north to Illinois and Indiana.
Blinding snows dominated the system's backside and halted travel over sections of 4 states from Colorado and Wyoming into western Nebraska and South Dakota. Snowfall reached 1-2 feet in Denver and up to 4 feet nearby in the mountains. An area three miles southeast of Pinecliffe, Colo., was buried by 45.8" of new snow and drifts in Wyoming were up to 6 feet tall.
Warming slated later next week -- but it may not last
Much cooler air hits Friday night into Sunday morning. Gusty west winds will add to the chill of the 50-degree Halloween Day predicted Saturday. Longer range models hint at the potential for significant warming later next week into the following weekend. The predicted "warm-up" has the look of an El Nino inspired temperature increase. But, several key cold weather indexes turn negative toward the end of the coming two weeks -- suggesting any warming may not last.
REMINDER: Daylight Saving Time ends Sunday morning at 2 a.m. Turn clocks back an hour before heading to bed Saturday night. The change means it will feel like we have an extra hour of sleep Sunday. But sunsets will move from 5:46 p.m. Saturday to 4:45 p.m. Sunday as a result of the change.
Dear Tom,
I moved to Chicago several months ago and I've heard that winters here are brutal. Does the cool weather now mean this winter will be even more brutal than usual?
Tami
Dear Tami,
Take heart. A review of Chicago's autumn and winter temperature statistics in years past shows that a chilly October (such as we're experiencing this year) is usually followed by an abrupt temperature turnaround. Winter is cold, of course -- Chicago's winters are always cold -- but a winter with above-normal temperatures often follows an October with subnormal temperatures.
May we take exception to your characterization of Chicago winters as "brutal"? We believe that's too harsh. If you moved here from a milder climate, as your question implies, Chicago's winter weather will shock you initially, but you'll quickly become acclimated.
It often takes the powerful winds of a large autumn storm to sweep warm air into Chicago this time of year. That's precisely what happens Thursday in advance of the wind-driven and potentially thundery waves of rainfall expected to produce fall's 2nd heaviest rainfall here Thursday night and Friday. An average of 30 computer rainfall projections suggests 1.19" may fall before Friday closes -- but predictions range as high as 2.57". It will take only 0.6" of additional rain to push the month into the ranks of Chicago's 10 wettest Octobers on record over the past 139 years. At Wednesday's close, October's official O'Hare total stood at 4.63".
Thursday's strengthening southeast winds are predicted to gust to 30 mph by nightfall and are likely to grow even stronger at times Thursday night and Friday. They represent a key element of the approaching storm. Any thunderstorms which arrive within the storm's expansive rain shield may well be able to harness energy from the 60-plus mph winds predicted just above the surface, transferring some of that wind energy down to the surface as powerful gusts.
Before the downpours get going late Thursday night, Chicagoans are in for something of a meteorological treat. Sunshine, in short supply this month -- it's been the 5th cloudiest October on record and the least sunny in a quarter century -- should be abundant.
The day's southeast winds sweep into North Shore suburbs after a trip over Lake Michigan's cool waters. That's a development expected to restrict highs in Waukegan and Kenosha to near 60 degrees while Chicago's lakeshore reaches the mid 60s and some warmer south and southwest suburbs peak in the low 70s. The city has yet to log a 70-degree temperature this month, making it only the third October to do so since 1871.
Storm buries Colorado under 2-plus feet of snow;
threatening Plains severe weather outbreak
The storm behind Chicago's two day "warm-up" has hammered the Rockies and western Plains with the region's biggest snow this season. Totals late Wednesday had reached 35" at Pinecliffe, 28.6" near Nederland, 28.5" just outside Golden and 14" at Boulder -- all in Colorado. The area just south of Denver was under a new 11" snowpack as night fell Wednesday.
A severe weather outbreak threatens to the east in the storm's front-side warm sector Thursday. Areas from Texas north to Oklahoma, Arkansas and southern Missouri are at risk for damaging thunderstorm winds including possible tornadoes.
Dear Tom,
We're planning an ocean-side vacation at Waikiki Beach in Honolulu, Hawaii, and have become concerned about the tsunami threat. Any thoughts?
Kim Larson
Dear Kim,
The catastrophic tsunami of Dec. 26, 2004, in the basin of the Indian Ocean raised worldwide awareness of the deadly potential of such occurrences. Your concern is justified because, despite the Indian Ocean event, the Pacific Ocean, in which Hawaii is located, is encircled by the notorious "Ring of Fire" and is the world's most tsunami-prone ocean.
That said, be advised that Hawaii has had long experience with tsunamis and, with the National Weather Service's "TsunamiReady Program," has an excellent warning system in place. The Weather Service's Pacific Tsunami Warning Center, located in Ewa Beach, Hawaii, with a staff of 15, maintains 24-hour vigilance.
October often brings Chicago some of its nicest weather before the dark, dreary, chilly days of November and December set in. However, October this year has been November-like, with persistently cloudy,chilly, wet weather. Through Sunday the month has had just 39 percent of its possible sunshine, on par with November's typical 40 percent. The city has recorded nearly twice as many days with precipitation as usual and already ranks as one of the wettest Octobers, with a week remaining. It has been cool, as well, with temperatures well below normal. Bucking historic trends, October 2009 has yet to record one 70-degree day in a month that normally produces eight. The upcoming week promises a continuation of the cloudy, wet weather, but a break in the rain on Thursday coupled with strong southerly winds ahead of a Plains storm system has the potential to send the mercury surging to 70. The warm-up will be brief, with temperatures dropping into the upper 30s by Halloween morning. But afternoon sun should send the mercury back to about 50 for trick-or-treaters.
Dear Tom,
Our 5th grade science class is studying the sun. Can you tell us the highest and lowest temperatures in the world?
Chloe, Justin, Michael and Danielle
Fernway Park School, Orland Park
Dear students,
The temperature extremes on our planet span an amazing 265 degrees. The world's highest temperature of 136 degrees was recorded at El Azizia, Libya, on Sept. 13, 1922. Contrast that to a low temperature of minus 129 degrees measured at Vostok, Antarctica, on July 21, 1983. Temperature extremes in the U.S cover a substantial but smaller range of 214 degrees. The nation's highest temperature was 134 at the Greenland Ranch in Death Valley, Calif., on July 10, 1913. The lowest was 80 degrees below zero at Prospect Creek, Alaska, on Jan. 23, 1971. Excluding Alaska, the lowest reading in the Lower 48 was minus 70 at Rogers Pass, Mont., on Jan. 20, 1954.
Rain finally ended this morning after a prolonged soaking that began on Thursday. Shortly after 9 a.m. Saturday morning with temperatures hovering in the upper 30s morning, the season's first snowflakes were observed at Midway Airport mixed with the rain. Skies cleared in the afternoon bringing the city its first sunshine since last Wednesday. More rain is expected to fall in the area in the upcoming week adding to the month's already impressive rainfall totals. This October is already the ninth wettest at Midway Airport with 4.83 inches on the books. The city's wettest October was in 1954 when 12.06 inches fell.
A long-shot at a 70
In addition to the rain, brisk south winds ahead of a midweek storm system will send the mercury climbing back into the 60s. With temperatures running more than 5
degrees below normal, October 2009 has yet to record an official 70-degree temperature, a value reached in all but two Octobers here since 1871. Though clouds and showers
will likely keep the mercury from reaching the 70-degree mark, readings here should climb well into the 60s Thursday afternoon. Chilly weather will follow on Friday, but temperatures should moderate Saturday setting the stage for a dry and seasonably cool Halloween.
Dear Tom,
While the Halloween 1991 "Perfect Storm" was raging in the Atlantic, Minneapolis was hit with a major snowstorm. Were the storms related?
--Rick Mullin
Dear Rick,
Though occurring half acontinent apart, the storms, though separate entities, were related. The "Perfect Storm" made famous by Sebastian Junger's novel and the movie raked the Eastern Seaboard from Oct. 30 to Nov. 1, 1991. At the same time an equally amazing storm was bringing record snowfall to Minnesota. From Oct. 31 to Nov. 2 the blinding snowstorm dropped 28.4 inches of snow on the Twin Cities, a single storm record. Duluth was buried by 36.9 inches, the largest storm total in Minnesota history. Because of the strength of the Atlantic storm, the Midwest storm could not move east and was forced north, prolonging the snow in Minnesota.
The last vestiges of the mega-rain producing storm which walloped the area with 2 to 4 inch rains Thursday night and Friday aren't long for the Chicago area Saturday. The cloudy, sporadically drizzly weather with which the day opens gives way to brightening skies toward midday and some welcome sunshine Saturday afternoon. Temperatures, which peaked for a time in the 60s Friday -- 61 at O'Hare and 62 at Midway -- will average 12 degrees cooler Saturday and may have trouble breaking out of the upper 40s in some areas.
October rainfall, typically just 2.71", is running twice the normal pace in the city -- but has totaled as much as 7.62" at south suburban Flossmoor, 7.28" at Hebron, Ind., and 6.79" at Glenview. All the wet weather this month makes October 2009 among the wettest of the past 139 years. The 4.15" at O'Hare is the 13th wettest to date since 1871; Midway's up to 4.80" -- and there's still a week to go. Rain has fallen on 17 of the month's opening 24 days -- that's 71 percent of them!
It was snow -- not rain -- which fell on the departing storm's backside in Minnesota and northern Wisconsin Friday. Stewartville, Minn., was hit with 4.2" while Rochester was whitened by a 3" snow pack and Eau Claire, Wis., was hit by 2".
Next wet storm could warm Chicago mid-week before a Halloween weekend temp crash
A disturbance due to sweep into the area Sunday brings clouds and a few possible mainly afternoon sprinkles -- with a better chance of showers Sunday night into Monday. But it's Wednesday and Thursday which sees a broad fetch of gusty south winds make their way into the area as a storm develops in the Texas Panhandle Wednesday and lifts into the Great Lakes Thursday and Friday, inducing warmer temperatures. The set-up could even support gusty thunderstorms Thursday.
The system's progress will have to be monitored: A bit of sunshine or a slowdown in its northeast trek across the Heartland could permit temperatures to become even warmer than the 60s now indicated to occur. Weather history shows 80 percent of the final weeks of October have produced 60s and 45 percent have hosted 70s.
Dear Tom,
I received an email showing people walking on a frozen Niagara Falls in 1911. Is that real, and if so how cold was it?
George Koziol, Chicago
Dear George,
Those photos have been making the rounds for many years. While not commenting on their validity but only on the weather, they were probably not taken in 1911 but in late January or early February 1912 when severe cold gripped the Great Lakes region. Weather records indicate that January 1912 was the coldest January on record to date in the Lakes region, not only in terms of average temperature but in consecutive days of below zero weather. Buffalo recorded only five days with highs above freezing during all of January. Intense cold continued in early February, and that six-week period ranked as one of the coldest on record at that time. Buffalo did not climb above freezing from Jan. 30-Feb. 16 and dropped to 13 below zero on Feb. 10.
Downpours swept into the Chicago area Thursday and have continued overnight. The storm is expected to produce the biggest rainfall tallies in two months--more than 2 inches in some areas. It comes in an October which has seen rain 16 of 23 days. But, not since 2.12 inches fell between Aug. 26-29 has a wetter system hit the area. It's arrived as area farmers struggle with what is already the latest harvest in recent memory, a development brought on by an extraordinarily wet spring and cool summer. The latest rains all but guarantee field work won't resume for 3 to 4 days, according to John Hazzard who farms in Will County's Wilmington area. What's more, this year's fall color display---arguably one of the best in recent years---may well be adversely affected as the current system's wind/rain combo brings down leaves.
Area rainfalls by late Thursday evening had reached 1.85 inches at Kenosha, WI, 1.58 Rockford, 1.37 Sandwich, 1.34 Lake Geneva, 1.24 Henry and 1.20 in Glenview---totals expected to rise significantly in overnight downpours expected to extend into the first hours of Friday morning. While occasionally heavy rains are projected through mid-morning, easing to lighter showers by lunchtime and to lighter, far more sporadic sprinkles Friday afternoon, the storm's backwash showers---showers which sweep around such a system's west and southern flank--aren't likely to fully depart the area until later Saturday afternoon. Still another system--lacking the huge moisture budget of this one---may ignite some additional showers Sunday afternoon and night. And another wet system seems a good bet mid-next week.
Louisiana tornado overturns 18-wheeler as rains top 4 inches in Arkansas
Driving rains weren't the system's only effect in a 1,000 mile swath of terrain extending from Louisiana and the Gulf of Mexico to Wisconsin and Michigan. A tornado touched down just after noon Thursday in Jennings, Louisiana, overturning cars on Interstate 10 and flipping an 18 wheeler on its side. Big rains to Chicago's south included 4.20 inches at Arkadelphia, AR, 3.98 at Alexandria, Louisiana, 2.68 at Ames, Iowa and 2.26 at Kirksville, Missouri.
Dear Tom,
In your Oct. 22 column you mentioned that 1992 had the fewest number 80 degree or higher days (58) before this year (56). What was the winter of 1992-93 like?
Frank Davis Prospect Heights
Dear Frank,
The winter of 1992-93 was slightly above normal in both temperature and snowfall. The winter averaged 26.4 degrees---about a degree warmer than a typical Chicago winter. There were only four days of subzero weather, with the winter's lowest reading dropping to just minus 4 degrees on Feb. 24. Snowfall totaled 46.9 inches as compared to a city-wide average of about 40 inches. There were no huge snowstorms---the biggest totaling around 7 inches, and the season's deepest snowpack reached only 8 inches. The winter's first major snow, a 5 inch affair, did not occur until Dec. 9-10.
Wind-driven rain and a sharp temperature pullback ride into town Thursday and Thursday night with the month's wettest storm to date--a system likely to linger through Friday and Saturday. Initially patchy light rain is to build steadily in coverage and intensity Thursday as will winds, which are predicted to shift northeast off Lake Michigan shortly after daybreak. The strengthening northeast flow will take a mighty toll on temperatures, which managed the month's first 70-degree readings over much of the metro area Wednesday. Though Thursday opens comparatively mild, intensifying rainfall from a lowering and thickening cloud base and surging winds expected to reach 25 m.p.h. late in the day and 35 m.p.h. at times Thursday night should lop 10 to 20-degrees off the warm levels observed Wednesday. Readings are predicted to tumble to the low 50s by Thursday evening's rush hour where they are to linger into Friday. October's generous rain tally to date (2.23 inches going into this storm)--already above normal--is likely to surge by as much as 2 inches in the downpours predicted to fall most heavily between mid and late Thursday afternoon and early Friday afternoon. The incoming storm has incorporated moisture from the remnants of once powerful Hurricane Rick with eastern Pacific origins.
Temperatures Wednesday reached 70-degrees at Midway and the lakefront and 69-degrees at O'Hare. Other area readings included 73-degrees at Aurora and Joliet, 72-degrees at Gary and Marseilles and 71-degrees at Romeoville, Burr Ridge, Wheaton, West Chicago and Plainfield.
Snowfall in south Colorado's high country tops a foot and a half, Minnesota close to 3 inches
The incoming storm produced 17 inches of snow in south-central Colorado Wednesday while up to 3 inches whitened Minnesota's Arrowhead region north of Duluth.
Dear Tom,
Is it true that Chicago had twice as many days of 80 degrees or higher in 2007 than we have had this year?
Pat Byrne Hoffman Estates
Dear Pat,
This year's lack of warm days has been extraordinary. So far in 2009 Chicago has logged only 56 days at Midway Airport where the mercury has reached at least 80 degrees. That is the lowest total there since records began in 1928, besting the previous record of 58 days during the cool summer of 1992 when volcanic haze from Philippine volcano Mt. Pinatubo reduced temperatures world-wide. Ironically the year with the most days of 80 or higher was one year earlier in 1991 with 108. In 2007 the city reached 80 or higher 103 times falling a little short of doubling this year's anemic number.
An October which fails to produce at least one 70-degree temperature is virtually unheard of in Chicago. A 70-degree high high has occurred in 136 of the past 138 Octobers---98.6 percent of them. But this month to date, the highest reading here has been 65 degrees recorded this past Monday. It's a situation in stark contrast to the 84-degree high which occurred a year ago on Oct. 12. This is to change Wednesday. All appears go for a number of afternoon highs across the Chicago area which reach or sneak above 70-degrees amid strengthening south winds. Sunshine will play a role. Just how quickly lingering morning clouds and spotty showers exit the area will be a key in determining precisely how warm afternoon readings here rise. Various indicators suggest an O'Hare high which may peak between 70 to 73-degrees. Late October 70s are not uncommon, having occurred beyond the 21st in 64 percent of years since 1871.
Highs Tuesday, restrained a bit by the arrival of afternoon clouds, still managed to hit 62-degrees at O'Hare and 64-degrees at Midway. Readings in southern sections of the metro area were even higher, reaching 70-degrees at Marseilles and Pontiac and 68-degrees at Kankakee.
Windy, wet late week Chicago storm to include Pacific Hurricane Rick moisture
Wednesday's warm up won't last. A southward plunge of colder air over the Rockies and western Plains is helping spin up a storm expected to arrive with wind and rain here Thursday into Friday. A series of 15 computer rainfall projections puts more than an inch and a half of rain into the area between Thursday and Saturday night and suggest a wind shift to the northeast by Thursday afternoon will send temperatures diving. Of particular interest may be the entrainment of tropical moisture from the remnants of Hurricane Rick---only this past weekend, the second most powerful eastern Pacific hurricane since the 1960s--the storm's sustained weekend winds topped 180 m.p.h.
Dear Tom,
What does a cool October say about the following November? Here's hoping your crystal ball can offer some good news.
Doug Geist
Dear Doug,
Indeed it can. A review of Chicago's historical October and November temperature data indicates that far below-normal temperatures in the Oct. 1-19 period (such as we have experienced this year) do not carry into November. A sharp temperature turnaround usually occurs.
This year, October's temperatures (through the 19th) have averaged 46.9 degrees -- 8.0 degrees below normal -- and that is the chilliest Oct. 1-19 in the 51 years for which temperature data are available at O'Hare International Airport.
We looked at November temperatures following ten comparably chilly Oct.1-19 periods. The good news is that temperatures in nine of those ten Novembers were at or above normal.
Temperatures beneath Monday's sunny skies surged to the area's highest levels in three weeks, reaching 65-degrees at O'Hare, 66-degrees at Midway and Kankakee, 67-degrees at Chicago's lakefront and 68-degrees at both Gary and Joliet. The day delivered 98 per cent of its possible sun--the most in two weeks--and the temperature surge it helped produce ended, at least for the time being, an extraordinary 21-day string of below normal temperatures--including a 45 degree high 3 days earlier on Friday. The cool spell is behind Chicago's 3rd coldest October open since 1871. The first 19 days of October averaged an eye-popping 9.6-degrees below the 139 year average as the warm-up began.
October's track record at producing 60s has been abysmal--the worst of the past 113 years. Monday's 65-degree official high at O'Hare was only the 5th this month--less than half the long-term average of 13 and well behind last year's 17 to date.
The break in the rain and wet weather has finally allowed area farmers--who are as much as three weeks behind in the autumn harvest because of inclement weather--to get out in their fields. USDA reported Monday that only 11 percent of Illinois' corn has been harvested--far below the most recent 5-year average of 68 percent. The 2009 harvest across the 18 states responsible for 94 percent of last year's corn production has reached only 17 percent versus the 46 percent recent average.
Think this fall's been wet? Last autumn had logged 15.04 inches by now
While October 2009 has been wet---2.20 inches vs. the normal of 1.63---the full autumn season which began Sept. 1 has actually produced less precipitation than normal: 3.23 inches vs. 4.90. And the 2009 tally is dwarfed by the fall tally 15.04 inches on the books by this time a year ago.
Dear Tom,
Has this been the coolest year in memory, or is that just my impression?
Alex Vesselinovitch
Dear Alex,
2009 has been a cool year thus far, but memories and impressions can be deceiving.
Averaged from Jan. 1 through Oct. 17, this year's temperature stood at 51.4 degrees, as registered officially at O'Hare International Airport. A computer sweep of the city's entire 139-year official temperature data base (1871-2009) indicates that 2009 ranks 26th coolest. That places this year among Chicago's coolest 19 percent of all years, but 25 years had lower average temperatures in the period from Jan.1 through Oct.17.
The chilliest year in the data base is 1875, with an average temperature of 47.0 degrees. Even when ranked among the 51 years (1959-2009) for which temperature data are available at O'Hare, 2009 is merely the 11th coolest.
High temperatures Sunday again barely surpassed 50 degrees despite 97 percent of possible sunshine, but Monday will be a different story. Warmer air will ride into northern Illinois on strong southwesterly winds, and afternoon readings are expected to rise well into the 60s. After the coldest October start since 1876, southerly winds should persist the next four days with highs averaging 5 degrees above normal. The extended period of southerly winds is due to a slow-developing low pressure system that will move out of the central Plains and cross the Mississippi River on Thursday. A broad band of showers and thunderstorms with 1 to 2 inches of rain will cover Illinois on Thursday. Even as the low moves slowly east away from the area, clouds and scattered showers will persist into Saturday.
Cold Sunday
Record low maximum temperatures were recorded Sunday in every eastern seaboard state from Virginia to Florida. Miami registered a record low maximum of 71 degrees Sunday, after a record high of 92 Saturday.
Dear Tom,
Why are weather people called meteorologists? Since they deal with the weather and not meteors, it seems more appropriate to call them "weatherologists."
Claire Gerbeck, Oak Park
Dear Claire,
The derivations of many words in the English language can be traced to the languages and literature of ancient cultures, and such is the case with "meteorology." It dates back to early Greece, when anything that was suspended in the air or fell from the sky (clouds, rain, rainbows, meteorites, etc.) was referred to as a "meteor."
Aristotle (384-322 B.C.) presented a series of treatises on natural phenomena in 340 B.C. Entitled "Meteorologica," they covered that era's knowledge of weather, astronomy and related subjects. Because much of "Meteorologica" dealt with weather, the term meteorology became linked with weather and atmospheric studies.
Saturday afternoon Chicago temperatures briefly rose above 50-degrees
for the first time in over a week. With the ridge of high pressure
drifting east, warming southwest winds will finally grab a toehold over
northeast Illinois. Readings will rise modestly today into the mid to
upper 50s and then approach the 70-degree mark Monday and Tuesday.
Cloud cover could temper the early workweek highs, but the potential is
there. Low pressure is expected to develop over the central plains and
approach the Midwest Wednesday. Prolonged moist southerly flow from the
Gulf of Mexico north up the Mississippi Valley will prime Illinois,
Wisconsin, Lower Michigan and Indiana for potentially heavy rains
Thursday.
Record low high temperatures over the southeast
The effects of the cold air hit the southeastern U.S. hard Saturday
with record low high temperatures in the 50s recorded in the Carolinas,
Georgia, and Tennessee. In Florida record low highs were set in
Tallahassee (60 degrees) and Orlando (72 degrees), but the cold front
had not quite reached Miami which observed a record high of 92 degrees.
Dear Tom,
Growing up in Chicago in the 1950s I remember an October with some very heavy rain and a lot of flooding. What year did that occur?
--Stuart Chambers
Dear Stuart,
Without a doubt you are remembering October 1954, the city's wettest October on record. The month recorded an official 12.06 inches of rain with most of it falling early in the month. During the morning of Oct. 3, thunderstorms dumped nearly 4 inches of rain that produced widespread flooding of basements and viaducts. Less than a week later devastating floods returned as Midway Airport recorded 6.72 inches of rain in a span of 48 hours between Oct. 9-11. West and south portions of the metropolitan area got 10 to 12 inches. A number of Loop buildings were flooded, and the Chicago River rose so high that numerous bridges were inoperable.
After a high of 45 degrees and a low of 39 degrees Friday, this October still ranks in the top three coldest in Chicago records dating to 1871. Today will not be much different, but warmer days are just ahead. Saturday will mark the 20th consecutive day with below-normal temperatures in Chicago and while warmer, Sunday will make it 21--but Monday could finally signal the return of above-normal 70-degree readings. A shift in the upper-air jet stream pattern will allow the return of warming southwesterly winds to northeastern Illinois for the first time this month. Low pressure will bring showers and thunderstorms midweek followed by a brief turn to cooler weather later in the week.
Eastern extremes
Miami registered its hottest readings ever (94 degrees) for so late in the season Friday, marking an October record 13th straight 90-degree-plus day. At the same time northern Pennsylvania was digging out of a heavy, wet 5- to 9-inch snow with additional snow forecast to hit later Saturday night and early Sunday.
Dear Tom,
Do you happen to know the derivation of "blizzard"?
Robert Gow
Dear Robert,
It's a relatively recent word, and it originated in the United States or England. By the early 1800s in this country, blizzard meant a cannon shot, a rapid volley of musket fire or a severe blow. Frontiersman Davey Crockett (1786-1836) was described as "speaking a blizzard" (a verbal blast) during a dinner speech and, on another occasion, taking a blizzard (a volley of shots) at a deer.
At about the same time in the English Midlands, blizzer referred to a severe wind and snow storm.
The first documented published uses of blizzard appeared in a few newspapers in Iowa in March and April of 1870 to describe a fierce winter storm in that area. Thereafter, blizzard came to be recognized as descriptive of a severe, wind-driven snowstorm.
What an October! Cool weather is well into its third week and still has two days to run. Gusty northeast to north winds and a steep 30-degree temperature drop in the first mile of the atmosphere set the stage for lake-effect rain showers Friday into Saturday evening before sunshine returns Sunday for the first time in more than week. The warming which follows arrives on gusty southerly winds Monday and Tuesday sending temperatures into recovery mode and boosting readings here to their mildest levels in three weeks.
Thursday's temperatures were anything but mild--and would have been at home in late November. The day's 44-degree official high equaled readings observed here for the date in 1876, 1909 and 1943--each tying as Oct. 15's coldest on record. The tenacious cold spell--which is to last into Sunday morning before breaking--produces a 19th day of below normal temperatures Friday and limits highs to the 40s for a 7th consecutive day--the most ever so early in the season. Chicago's average temperature over the month's first 15 days slipped Thursday to 47.3-degrees---the city's chilliest October open in the 133 years since 1876. Not only has it been cool---it's been cloudy and wet. Rain has fallen 10 of the past 15 days and has totaled 2.13 inches---nearly an inch (0.85) above normal. The damp weather has allowed only 38 percent of October's possible sunshine to date---58 percent is typical.
Not all of the country is shivering. South Texas broiled in unseasonable heat. Readings hit 100-degrees at McAllen and 99 at Del Rio.
Gusty downslope winds sweep Colorado during Thursday balloon episode
The 20-foot-diameter, helium-filled balloon first feared to be carrying a 6-year old as it took to the skies above Colorado Thursday afternoon, was whipped by gusty winds sweeping out of the mountains into the state's eastern Plains. These katabatic or Chinook winds gusted at times as high as 28 to 50 mph. The compressional warming they set in motion sent eastern Colorado temperatures soaring to near 70-degrees.
Dear Tom,
A couple days ago, while talking about a powerful storm hitting California, you mentioned heavy snow in the mountains, but here in Tahoe, at 6,200 feet, it was pouring rain.
Jimmy Smith, Tahoe, Calif.
Dear Jimmy.
Early-season snowstorms in California's mountains are usually confined to the most lofty elevations of the Sierra Nevada Mountains. It's a matter of atmospheric physics. Air expands and cools when it rises, losing 5.4 degrees for every thousand feet of vertical ascent in clear air and 3.3 degrees when it is saturated with moisture (in fog or clouds). When humid air from the Pacific Ocean ascends the Sierra Nevadas, it cools at a rate of 5.4 degrees per 1,000 feet of vertical rise until clouds form, after which the chill rate occurs at 3.3 degrees per 1,000 feet. Rain at Tahoe (6,200 feet) at, say 40 degrees, would likely be snow at 30 degrees at 9,200 feet.
Chicago remains mired in the chilliest early October in 22 years. The opening 14 days of the month, with an average temperature of 47.6-degrees, are well below the 57.3-degrees observed during same period over the past 138 years and 10.7-degrees cooler than a year ago--chilly enough to rank third coldest since 1871. The only Oct. 1-14 periods which have been colder occurred in 1876 (46.0-degrees) and 1987 (47.5) underscoring just how unusual the current chilly spell is.
All indications point to Thursday becoming the 18th consecutive day temperatures post a deficit and the sixth day highs fail to reach 50-degrees, establishing a new record for the most early season daytime readings which fail to break out of the 40s. With both Friday and Saturday predicted to stay in the 40s, the string is likely to end up at 8 days, something which doesn't happen here most years for another 5 weeks.
Rain falls across the Chicago area Thursday, the latest offshoot of a mammoth Pacific storm system which has whipped the West with 100 mph mountaintop wind gusts in recent days and stunning rainfall up against some of California's westward facing mountains. Totals reached 21.34 inches at Mining Ridge in Monterey County, roughly halfway between San Francisco and Los Angeles. A wind gust of 135 mph whipped Tahoe City, Nev. Wednesday and gusts of 70 mph raked San Francisco. Even sections of the Salt Lake City, Utah area registered 50+ mph gusts.
Dear Tom,
So far this October the highest temperature has been just 62 degrees and the forecast calls for continued chilly weather. Have we ever had an October that has failed to produce a 70 degree day?
Gene Maxwell
Dear Gene,
October is usually Chicago's last nice month before the dark, damp and chilly days of winter set in. Typically the area sees about 10 days with highs of at least 70 degrees, and usually there are at least a couple of days in the 80s. Checking temperature records dating back to 1870, climatologist Frank Wachowski found only two Octobers that failed to produce 70 degrees--1885 and 1917. In sharp contrast to those years, October 1963, the city's warmest on record, was a banner year for days of 70 or higher-- with 24 on the books. That month tallied 11 days in the 70s, 12 in the 80s and even a 94 on Oct. 6.
October's already impressive temperature deficit keeps growing. The month is running 8-degrees below normal---and the unseasonably chilly air which took hold here 17 days ago is showing no sign of departing through Sunday morning. Tuesday's 47-degree highs at O'Hare and Midway made it the chilliest Oct. 13 here in 82 years. The readings were 17-degrees below normal and 30-degrees lower than the 77-degree high a year ago---and missed by only 2-degrees the record low daytime maximum of 45-degrees set in 1909. It marked the fourth consecutive day in which temperatures failed to reach 50-degrees, a new early season record. Daily highs are predicted to remain below 50-degrees through Saturday.
The season's chilly, wet weather and recent frosts have hit Illinois farmers very hard producing one of the latest harvests in recent memory. The USDA reported Tuesday that only 57 percent of the state's corn crop has reached maturity compared to the 98 percent 5 year average. Late planting resulting from the spring's prolific rainfall and this summer's cool temperatures were factors. But most telling are the dismal harvest numbers to date. Just 6 percent of the state's corn has been harvested--56 percent is normal--while only 10 percent of Illinois soybeans have come out of the fields versus a five year average of 64 percent.
First storm of season lashes California; 8-inch-plus rain, 4+ ft. snows and 129 mph gusts
The season's first powerhouse storm--and not the last if the coming cool season follows trends observed in previous El Nino periods----lashed California Tuesday. 129 m.p.h. wind gusts were clocked at the 8,700 ft.level Donner's Summit and rainfall hit 9.32 inches at Fremont and 6.23 inches at Oakland. Snowfall in the Mammoth Lakes area was predicted to reach 4 feet at higher elevations. Waves of energy off that storm are behind the prediction of clouds, increased winds and periods of sprinkles and rain the next three days across the Chicago area.
Dear Tom,
We will be vacationing in Hawaii the entire month of February. What might be the effects of El Nino there?
Lucille Pirri, Deerfield
Dear Lucille,
El Nino, abnormal warming of water in the eastern tropical Pacific Ocean, is now occurring and is forecast to persist at least several months. The weather impacts of El Nino are global in scope, something Chicagoans, situated in the central United States, easily overlook.
The weather effects of El Nino are greatest in winter, and in Hawaii the primary impact is drought. That's bad news because water is chronically in short supply in Hawaii, and the islands are already experiencing severe drought. El Nino is likely to exacerbate the situation.
Other effects: lighter trade winds than usual and booming surf on west- and north-facing coasts. Finally, hurricanes, rare in Hawaii, are somewhat more frequent in El Nino years.
Not since 1987 have the opening 13 days of October been this chilly. The month is running more than 9-degrees below the long term average and 7-degrees cooler than the same period in 2008. It's a temperature trend which suggests home heating here is running at a pace 70 percent above the 30 year average and 80 percent ahead of last October.
The mercury struggled to reach 48-degrees Monday---a far cry from the summerlike 84 recorded a year earlier---becoming the third consecutive day Chicago's high temperature failed to get out of the 40s. In only four years have three back-to-back daytime 40s occurred by now---and a fourth day in the 40s Tuesday would become a early season first, having never occurred here since official weather observations began in 1871.
Midwest snowfall
An unseasonable snowfall whitened the Upper Midwest Sunday night and Monday. 4.2 inches fell in St. Paul, Minnesota while 3 inches fell at Newald in northern Wisconsin.
Warmer next week
Big changes coming: Temperatures could surge 60-degrees higher by next week in the Plains; 20+ degrees warmer here!
Cool as it's been, weather history strongly suggests Chicagoans haven't seen the area's last warmth. Temperatures, expected to surge 60-degrees higher in the Plains by this time next week, may well top 60-degrees as early as Sunday afternoon in Chicago and 70-degrees next Monday---a welcome change from the mid-November temperatures predicted to linger through Saturday. Weather records show an average of six 70s and sixteen 60s have occurred beyond Oct. 13.
Dear Tom,
Most of our weather moves from the west, but hurricanes in the Atlantic Ocean move to the west. Can you explain this?
Paul Knauth
Dear Paul,
Hurricanes move with the wind flow in the layer between the surface and approximately 40,000 feet aloft. During the summer and fall, a belt of more or less permanent high pressure extends across the Atlantic Ocean between the United States and northern Africa, paralleling the Equator.
Winds spiral out of the high in a clockwise direction and generate prevailing easterly flow across the tropical Atlantic, where most hurricanes form. Those prevailing easterlies steer hurricanes to the west, with a slight northward component. As hurricanes continue on that path, they eventually get caught in southwesterlies on the poleward side of the high pressure belt, and they "recurve" to the northeast.
Sunday's very chilly 44-degree high was more typical of Thanksgiving than just before Columbus Day, and it followed fall's first widespread hard freeze that dropped Sunday morning lows into the middle and upper 20s except for areas very close to the lake. O'Hare International Airport's 29 degrees was the coldest since April 2, when it dropped to 28, and Rockford's 25-degree low broke a record dating back to 1987, when it was 26. The Chicago area, along with much of the Midwest and Plains, has been locked in a chilly pattern since late September with little prospect for warming in the short term. Snow covers much of the Northern Plains and Upper Midwest, and up to 5 more inches are expected Monday.
Storm to hit Pacific Coast
The Pacific Coast is bracing for a major wind and rainstorm this week, heralding the opening shot of what could be a stormy El Nino-influenced winter. The brunt of the storm is headed for areas from Northern California to Washington, where 4 to 8 inches of rain could fall driven by 60 mph winds.
Dear Tom,
I remember a wonderfully warm Halloween when we trick-or-treated until our legs wore out. I think it was 1955. Can you clarify?
Judy Campbell, Orland Park
Dear Judy,
Though the early 1950s featured several warm Halloweens, 1955 was definitely not one of them. That year Oct. 31 started out very chilly with temperatures in the 30s along with some snow flurries, and though it warmed up a bit in the afternoon, the high reached only 51. If your time frame was off a few years, you might be remembering the city's warmest Halloween on record which occurred in 1950 with a summery 84 degree high. Other possibilities include 1952 (69 degrees), 1953 (70) and 1956 (68). After a string of recent cool Halloweens, last year turned out quite nice with the high temperature topping out at a balmy 70 degrees.
Temperatures will hover in the middle 30s this morning at the start of the Chicago Marathon, in sharp contrast to last year's 66 degrees at the start and the debilitating 75 degree opening of the heat-shortened 2007 event. It will be even colder inland where lows in the middle and upper 20s may threaten the record low of 27 set in 1996. The city has not recorded a day with above normal temperatures in two weeks, since Sept. 27, when the high reached a balmy 74.
Winter getting a jump start
The season's first flakes were recorded Saturday at Rockford and at far northwest suburban Harvard, while snow whitened the ground in much of Iowa. Des Moines received its earliest 1 inch snowfall on record when 1.1 inches fell, and two inches of snow in Denver forced cancellation of the Rockies-Phillies NLDS playoff game. A major snowstorm blasted Nebraska with nearly 14 inches at North Platte. Winter-level chill dropped the temperature to 11 at Rapid City, South Dakota. More snow is expected into Monday and winter storm watches are posted from the western High Plains into central Minnesota.
Dear Tom,
What is the warmest surface temperature at which it can snow?
--Tim Guimond
Dear Tim,
Checking through weather records, we found a case where it snowed during the 1970s in Jacksonville, Fla., when the temperature was 53 degrees. Temperatures were quite cold just above the surface and the air was very dry, which allowed cooling from evaporation to prevent the flakes from melting. In order for snowflakes to form, cloud temperatures must be 32 degrees or lower and the flakes must be able to survive the fall to the ground without melting. According to Chicago climatologist Frank Wachowski, snow has fallen here with temperatures as high as the middle 40s, but the flakes melted upon contact with the ground. Chicago's latest-in-the- season trace of snow occurred on June 2, 1910, when it was 44 degrees.
Cold air is hitting early this year. A subfreezing temperature -- similar to the one predicted at O'Hare Airport Saturday night and behind the freeze warnings which have been issued for the entire Chicago area -- didn't occur a year ago for another two weeks until Oct. 28. Saturday's 54-degree high is an early November level reading -- 11 degrees below normal. But the passage of a cold front, expected to shroud area skies in clouds as Saturday afternoon proceeds, is to bring snow flurries across Iowa into western Illinois before drying out -- intensifying cold air's grip on the area Saturday night and Sunday. Daytime highs are likely to rise no higher than the mid to upper 40s Sunday after recovering from the low/mid 20s across western suburbs in Sunday's predawn hours.
The onset of cold air each fall and winter is largely a function of astronomical changes. The sun set at the North Pole Sept. 22, and that region of the arctic is now in round-the-clock darkness. Days to the south -- including the Chicago area -- shrink from summer's arrival, which occurred this year on June 21, to the onset of winter on Dec. 21.
The decrease in solar energy sets the stage for cooling. It's a process which takes place most dramatically in the arctic. While Saturday is to host 3 minutes less sunlight than Friday in Chicago, the loss of daylight increases to 7 minutes farther north in Anchorage, Alaska, and to an amazing 28 minutes in the northernmost reaches of North America. It's little wonder cold air -- and eventually a reflective snow cover -- assembles fastest there.
October is off to a remarkably chilly, wet start. Temperatures have averaged 51.2 degrees -- more than 7 degrees off the long-term average. Rainfall in the wake of Friday's chilly downpours is 1.82" -- far from the 0.82" which is normal for the month's opening nine days.
Sunday's Bank of America Chicago Marathon to kick off in air 30 degrees colder than last year
Runners in Sunday's Chicago Marathon, subjected only two years ago to wilting heat which forced the race to be cut short, are likely to shiver in Sunday morning's mid 30-degree temperatures. The readings represent a 30-degree decrease from the mid 60s as the Marathon got underway a year ago and nearly 40 degrees from the ill-fated 2007 race.
Dear Tom,
"Something good comes of everything," is my dad's favorite saying. So, can you tell me what good might have come out of our cloudy, cool, rainy summer?
Joseph Heard, Chicago
Dear Joseph,
Many people dislike hot weather and enjoy rain and cloudiness; they were pleased. Here's something less obvious, but significant: less ozone air pollution.
According to the EPA, many U.S. cities from the Midwest to the Mid-Atlantic and Northeast experienced a summer with at least 80 percent fewer days on which ozone pollution reached unhealthy levels. Chemical reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight produce ground-level ozone, conditions likely to occur on hot, stagnant summer days. This summer's cool temperatures and above average rainfall and cloudiness were unfavorable for ozone formation.
Periods of rain extend into a second day across the Chicago area Friday and are likely to more than double O'Hare and Midway's modest 0.11-inch and 0.13-inch Thursday tallies. But it was the southern Midwest that was hardest hit by downpours spawned by the week's second storm. More than half a foot of rain (6.07 inches) had drenched Joplin in southwest Missouri by nightfall with 6.25 inches reported 110 miles to the northeast at Urbana, Mo. Downstate Mt. Olive, Illinois where a series of deluges continued much of the day, had measured 4.80 inches by day's end. The driving rains extended east across downstate Champaign and Decatur and to Bloomington and Indianapolis---areas in Indiana where 2-3 inches fell.
Abnormally cold air was on the move from the Plains into the Rockies threatening single digit low temperatures across Montana in coming nights---temperatures likely to challenge temperature records and produce an unseasonably chilly weekend in Chicago. The coldest air surges into the area Saturday night, possibly producing a brief shower or some flurries before temperatures tumble to the mid and upper 20s at the coldest inland locations west of the city and to within striking distance of the freezing mark at the city's official O'Hare thermometer. A 32-degree temperature hasn't occurred in the six months since April 17 and would bring an end to the 2009 growing season---defined as the span of time between the first and last frosts of the year. Despite an incredibly rainy cool spring and cooler than normal summer weather, Friday marks the 176th day of this year's growing season--longer than the 172 days considered normal.
Saturday cool--but Sunday and Monday chill November-like
While Saturday's low and mid 50s are nearly 10-degrees below normal, temperatures Sunday and Monday (Columbus Day) are likely to struggle to make the mid to upper 40s. A disturbance predicted to traverse the region late Sunday night and Monday morning could produce several showers of cold rain or perhaps mixed ice pellets. Any weekend flurries would be unusual. Only 10 percent of the 125 years for which snow records exist here have recorded a trace of snow this early in the season.
Dear Tom,
What should the weather be like in Rio de Janeiro for the 2016 Olympics?
R. J. McGee Chicago
Dear R.J.,
August is a very pleasant late winter month in Rio de Janeiro, which lies at the south end of the tropics just north of the Tropic of Capricorn. The 2016 Olympics will be held from Aug. 5 to 21, a time of year when daytime highs typically run in the middle 70s with morning lows in the middle 60s.
Temperature extremes for the month range from a high of 93 to a low of 54.
August is usually a dry time of the year in Rio with measurable rain falling on an average of just seven days during the month which typically receives 1.7 inches of rain. Humidity levels which can be oppressive during the Brazilian summer are moderate in August, and being a coastal city, Rio experiences frequent cooling breezes off the Atlantic.
The Chicago area---where more rain has fallen in the opening 7 days of this month (1.24 inches) than in all of September (1.03 inches) ---is in for a soaking over the next two days as the second storm in a week bears down on the area. The system, developing early Thursday across the Texas Panhandle, threatens downpours from Texas and Oklahoma to Indiana, and is behind the flood watches hoisted Wednesday across an 8 state area, including southern and central Illinois. As much 3 to 5 inches of rain may come down there Thursday and Friday.
Unlike earlier this week when the first system only brushed the Chicago area, rainfall estimates generated by 22 different computer model projections range from 0.36 inches to as much as 2 inches---a spread which may mimic the north to south precipitation distribution across the metro area. It would not be surprising to see 1-inch-plus totals in the region's hardest hit locations---especially from Chicago south.
Sunday night/Monday snowflakes not a slam dunk; would be quite unusual
The strongest outbreak of cool air since early April is to deliver a November-level chill to Chicago this weekend. It promises an unseasonably chilly weather regime with mid 30s for Sunday morning's Bank of America Chicago Marathon---far different than some in recent years which have been abnormally warm. And, while not yet a slam/dunk, cold rain showers Sunday night into Monday (Columbus Day) could be mixed with wet snowflakes. That will depend on the extent to which the still warm ground impacts air temperatures. Flurries this early in the season would be extremely rare. Only 12 of the past 125 years have recorded snow through October 12---Monday's date. That puts the climatological probability of flurries at just 10 percent.
Dear Tom,
A friend of mine from Ecuador told me that the weather Quito is almost always pleasant. Is this true?
Jeff Taylor Chicago
Dear Jeff,
Quito is located on the equator more than 9,000 feet above sea level and has a climate described as "eternal spring" with mild days and chilly nights. Temperatures are relatively steady through the year with daytime highs generally in the upper 60s and lower 70s and overnight lows in the 40s and 50s. The area's hottest days top out in the middle and upper 80s
and the coolest mornings drop to around freezing. The variable aspect of Quito's weather is mountain-induced rainfall with the city having definite wet and dry seasons. The dry season runs from June through September with monthly rainfall averaging 1 to 3 inches while the October to May rainy season has considerably more with amounts in the 3 to 7 inch range.
Powerful winds with the first of two autumn storms predicted to impact the region this week, whipped sections of the Chicago area with gusts topping 50 mph late Tuesday. A 63 mph blast was clocked at 9:05 p.m. three miles off Chicago's shoreline at the Harrison-Dever Crib and other gusts included 54 mph at the Weather Bug wind sensor at Queen of Angels School in Chicago, 50 mph at Algonquin, and 48 mph at Glenview. The storm responsible produced modest amounts of rain here---only 0.03 inches at O'Hare and 0.27 at Rockford--but drenched the Upper Midwest with 1.74 inches at Tomahawk and 1.55 at Oconto--both in Wisconsin.
Tuesday's stormy weather comes on the heels of the area's coolest October open of the past 6 years. Temperatures over the month's opening 6 days averaged 52.1-degrees--- 7-degrees below the 138 year average and among the 7 coldest such periods since observations began in 1871. In 6 previous years with comparable cool October starts, the sub-normal temperature trend remained dominant the remainder of the month.
A powerful new early season cool surge---including a potential for the first daytime highs which fail to break above 50-degrees since April, continues a threat this weekend into early next week. The chill's arrival in the U.S. is to ignite a new round of snowfall in the northern Rockies as it sweeps out of Canada. Winter weather advisories were issued in Montana for Wednesday.
A new storm threatens parts of the area with big rains Thursday
The week's second storm may may bring parts of the Chicago area as much as 1 to 2 inches of rain---especially in southern sections Thursday into Friday morning.
Dear Tom,
What is the earliest occurrence of measurable snow in Chicago?
Tanya Davis
Dear Tanya,
With the opening of October upon us it is time to start thinking about snow. Though the season's first measurable snow doesn't usually occur here until the middle of November, the city has experienced measurable snowfall on many occasions in October. The city's earliest measurable snowfall on record took place here just three years ago on Oct. 12, 2006 when both Midway and O'Hare airports measured 0.3 inches of snow. The snow was more significant in the northwestern suburbs where 1.2 inches fell at Mundelein and one inch at both Algonquin and Crystal Lake. One reason the snow was able to accumulate that morning despite the still warm ground was the intense rate of fall, that reduced visibilities to near zero in some areas.
The chilliest spell of weather here in over five months moves into a
9th consecutive day Tuesday---but under cloudier skies than in recent
days. Rainfall with the first of this week's two wet weather systems is
predicted to begin from the day's rapidly lowering and thickening
overcast by mid-morning and continues in waves through much of the
afternoon. A suite of the 11 most recent computer projections places
the day's potential rainfall from 0.10 inches to as much as 0.85---an
amount which comes on top of the 1.22 inches recorded here in the past
8 days---a period which has averaged nearly 5 degrees below normal.
Estimates based on temperatures since October's open suggest the cool
spell has led to home furnace use nearly 60 percent more than the most
recent 30 year average.
Gusty west winds, likely to top 30
m.p.h. at times Tuesday night, deliver a reinforcing shot of chilly
air. But, the far more significant cold surge---potentially the coolest
in more than 5 months and likely to limit high temperatures to the 40s
for the first time since last April---looms this weekend.
Wet storm system later this week could produce up to 3 times Tuesday's rainfall
A
frontal wave expected to sweep the area as the cold air approaches is
likely to produce a far wetter interlude than Tuesday's---doubling or
tripling the amount of rain to fall today.
Dear Tom,
Has there even been a tornado produced by a snowstorm or when snow was on the ground?
Mike Callan Lemont
Dear Mike,
It is common for tornadoes to develop on the warm side of storms that deliver heavy snow, but it would be extremely rare for a twister to develop on the cold, snowy portion. Recently, on Feb. 5, 2008, 64 twisters battered the South while heavy snow swept the central Midwest. Though twisters usually form in a warm, moist surface environment, there are always exceptions. Dr. Harold Brooks of the National Severe Storms Laboratory in Norman, Okla. tells of a twister at Altus, Okla., on Feb. 22, 1975, with temperatures near freezing. The F2 storm killed two and injured 12 as it ripped through a trailer park. Twisters have also occurred during warm-ups when pre-existing snowpacks have not melted.
The initial bursts of chilly temperatures in the autumn usually feel worse than they are because we're not acclimated to them. Saturday's and Sunday's afternoon readings in the upper 50s and lower 60s seemed quite cool, but perception is a relative thing. Relative to September, those temperatures were cool, but we would perceive comparable readings, should they occur in mid-January, as pleasantly mild. Averaged together, expected daily highs through the seven-day period beginning Monday work out to 56.1 degrees, or 9.8 degrees below normal. Should that occur, it will be the chilliest Oct. 5-11 period since 55.1 degrees in 2000, and the 14th coolest in 138 years of official Chicago temperature history.
Stand by for an Arctic blast
The weather pattern remains active and two vigorous storm systems have their sights set on Chicago. The first brings thunderstorms Tuesday, followed by a moderately strong surge of Canadian air. The second, on Thursday, introduces the season's first Arctic blast.
Dear Tom,
Can you suggest a place where the normal summer weather is moderate, with pleasant humidity and only rare 90-degree days? And in addition, where the climate is temperate year around?
Steve Cepa, Libertyville
Dear Steve,
Let's preface the answer with this comment: Even locations that normally enjoy year-around temperate weather will at times experience periods of extreme temperature and humidity conditions.
That said, within the continental United States coastal central and southern California probably comes closest to satisfying your criteria, both during the summer and year around -- roughly the area from Monterey to San Diego. And by "coastal" we mean within a few miles of the Pacific Ocean. Hot days as defined by 90 degrees or higher rarely occur there (versus Chicago's average of 24 days at Midway Airport) and winter readings in the 20s or lower are also rare.
Saturday's chilly temperatures, 11 degrees below normal for the date, were still several degrees above the city's record low maximum temperature for the date: 47 degrees in 1997. Today's daytime temperatures are set to moderate a tad, but still fail to crack the 60-degree level. Nighttime readings, too, are remaining on the chilly side. Taken together, Saturday's and Sunday's temperatures constitute the city's coolest weekend since April 11-12 (with high/low readings of 47/31 and 51/27, respectively).
A ridge of high pressure and its attendant dry weather moves into the area on Monday, and that means a sun/cloud mix along with moderately higher temperatures. However, an active regime continues to dominate the nation's weather and the next storm system to affect Chicago is crossing the Intermountain West on Sunday. It pushes toward the Midwest on Monday and its advance cloud shield should arrive here Monday evening. Those clouds build into showers later Monday night and continue, possibly with thunderstorms, on Tuesday.
Dear Tom,
Do you think anything can be done about the increasing levels of carbon dioxide in the atmosphere?
--Jim Wilson
Dear Jim,
Increasing atmospheric concentrations of carbon dioxide (CO2), up from 316 parts per million in 1960 to 383 parts per million in 2008, is of concern because, as a greenhouse gas, it is implicated in the issue of global climate change, and human activity adds about 34.5 billion tons of CO2to the atmosphere each year. To date, efforts to deal with this situation have focused on reducing emissions, but it is unrealistic to suppose that significant reductions are likely to be accomplished. However, Columbia University professor Wallace Broecker and his associates have proposed a novel approach: economically removing CO2 from the atmosphere, and they are perfecting a prototype device to do just that.
Clouds and scattered showers continue today, and even though the rain ends tonight, clouds and cool early November-like readings in the 50s persist into Sunday. Chicagoans have to turn back 25 weekends to April 11-12 to find a colder weekend.
Low pressure over Lake Michigan will slowly pull off to the northeast, moving into Canada's Ontario province later this weekend. This will allow a thinning of clouds and considerable sunshine to return to northern Illinois Monday. Clouds along with showers and thunderstorms will return to the metro area as another low pressure center moves out of the Rockies into the central Plains and approaches the Midwest Tuesday.
Cool turns cold late next week
Temperatures next Wednesday through Friday will be below normal, but computer models are currently in agreement that the season's coldest air yet could be ushered into the western Great Lakes and Chicago next weekend.
Dear Tom,
I enjoyed your column in which you explained why cumulus clouds have flat bottoms. Is there some way that an amateur weather buff and avid cloud-watcher like me can estimate how high those flat-bottomed cumulus clouds might be?
Andrew Browning
Dear Andrew,
Cumulus clouds form when warm air in the surface layer (that is, air within a few hundred feet of the ground) rises sufficiently far upward to be chilled to saturation so that its load of water vapor begins to condense into visible cloud droplets. The height at which that occurs depends mainly
on the temperature and moisture content of air (as indicated by the dew point) in the surface layer.
The height (in feet) above ground of the base of cumulus clouds can be estimated quite accurately with this rule of thumb: Subtract the dew point from the temperature and multiply the result by 230.
On a normal early-October afternoon, Chicagoans can expect daytime temperatures in the upper 60s -- that's the climatological expectation -- but, as humorist Mark Twain once quipped, "Climate is what we expect; weather is what we get." And the weather Chicagoans are likely to get in upcoming days includes temperatures as much as 15 degrees below normal along with clouds and considerably more rain than we want. Despite the overall chilly pattern, Tuesday's temperatures spike briefly to near 70 degrees. As of 9 p.m., Thursday's rain totaled 0.49 inches at Midway, nearly equaling September's full-month total of 0.54 inches.
Frosty temperatures
Suburban temperatures dipped into the middle and upper 30s early Thursday morning. Those readings, in combination with calm air and a clear sky, were sufficient to produce the autumn season's first frost in the metropolitan area. Weather observers in Arlington Heights and Mundelein observed patchy light frost on grass and roof tops. The early-morning minimum temperature at Mundelein was 36 degrees, as reported by Phil Rider.
Dear Tom,
Why is it that clouds are flat at the bottom and have irregular shapes on top?
Hans Weckerle
Dear Hans,
You have described cumulus clouds, the "dab of cotton" clouds that populate the sky on warm afternoons. When warm air ascends in rising currents, its pressure falls and its temperature drops at a steady rate of 5.4 degrees per 1,000 feet of vertical climb.
Rising air, if the process continues long enough, eventually ascends to a critical height and chills to a critical temperature at which its load of water vapor suddenly begins to condense. That defines the flat bottom of a cumulus cloud.
However, ongoing condensation at the cloud top, rather than being limited by specific air pressure and temperature values, occurs in irregular surges determined by constantly varying factors like available moisture and updraft strength.
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