The coldest air of the season ushers in the new year, and that’s in sharp contrast to the year we have just left behind. Officially, 2012 enters the record books as the mildest year in 142 years (1871-2012) of Chicago weather history. With an average temperature of 54.5 degrees, 2012 surpassed the previous record of 54.4 degrees registered in 1921. Tuesday’s high temperature, 20 degrees, will be the city’s lowest maximum temperature in nearly 11 months (since 20 degrees on Feb. 11, 2012).
And Chicago’s “snow drought” continues. Other than the possibility of flurries, the seven-day forecast cycle offers no hope for significant snow.
The weather pattern is ”progressive,” with weak weather disturbances moving quickly, one after another, from the northwest, each introducing more dry air and each effectively preventing the return of Gulf moisture.
Considering the water that flows into or falls into Lake Michigan and the water that flows out, how long does it take for the water in Lake Michigan to recharge?
Dan Correli, Chicago
It’s a complex question and the answer is, at best, an estimate. Hydrologists define the “flushing time” of a lake as the time required for the average outflow from a lake to drain it; the volume of a lake divided by the average rate of outflow. Lake Michigan’s flushing time is estimated to be 69.5 years. Permanent lakes with a flushing time less than a year are rare. They tend to have vigorous flow and their biological diversity is low because there is little time for nutrients to accumulate in the water. At the other extreme, lakes with flushing times greater than ten years are sensitive to external changes, such as pollution. At least one flushing is required to recover from pollution.
UPDATE: 2:50 pm
Some late snowfall totals from Downstate..
UPDATE 2:00 pm
At 2pm snow was falling south of Chicago in central Illinois
Peoria visibility 3/4 mile
Bloomington visibility 1/2 mile
Decatur visibility 1/2 mile
Kankakee visibility 1.5 mile
Springfield visibility 3/4 mile
Champaign 1/2 mile
Rantoul 1 mile
Some Downstate snowfall totals
A weather disturbance moving through the southern Midwest will spread a band on snow across portions of central Illinois into northern Indiana. Up to 2 to locally 3 inches of snow could accumulate in areas from Joliet and Kankakee south northeast into portion of Lake and Porter counties in northwest Indiana.
Visibilities could drop below one half mile in the snow that will create hazardous driving conditions.
INCLUDING THE CITIES OF...KANKAKEE...PONTIAC...WATSEKA...PAXTON...
1105 AM CST MON DEC 31 2012 /1205 PM EST MON DEC 31 2012/
...PERIODS OF MODERATE TO HEAVY SNOW EXPECTED THIS AFTERNOON...
SNOW IS EXPECTED TO DEVELOP AROUND OR SHORTLY AFTER MIDDAY AS AN
UPPER LEVEL DISTURBANCE INTERACTS WITH A SURFACE COLD FRONT MOVING
ACROSS THE AREA TODAY. THE SNOW COULD BE HEAVY AT TIMES BETWEEN
NOON AND 4 PM THIS AFTERNOON...WHICH MAY RESULT IN VISIBILITIES
FALLING UNDER A HALF MILE IN SOME OF THE HEAVER SNOW. THE SNOW IS
EXPECTED TO QUICKLY ABATE LATE THIS AFTERNOON...WITH ONLY SOME
LIGHT SNOW AND FLURRIES LINGERING INTO THE EVENING.
SNOW ACCUMULATIONS WILL VARY WIDELY ACROSS THE REGION...WITH A
VERY SHARP NORTHERN GRADIENT BETWEEN NO SNOW AND AN INCH OR TWO.
IT APPEARS THE HEAVIEST SNOW...OF 1 TO 2 INCHES...WILL FALL ALONG
AND SOUTH OF A LINE FROM NEAR PONTIAC TO KANKAKEE...TO VALPARAISO
INDIANA. DUE TO THE POSSIBILITY OF PERIODS OF HEAVY SNOW...THE
SNOW MAY QUICKLY ACCUMULATE ON UNTREATED AREA ROADS...LEADING TO
SOME POSSIBLE HAZARDOUS TRAVEL THIS AFTERNOON.
Today should mark the 310th day in a row with a high of at least 32°, a new record streak. If we hit 32° or more today as expected then this winter will rank #2 for the latest first sub-freezing high of the season. Today should also the 354th day this year we have seen a high of at least 32° . This year now moves into second place for the most days with a high of freezing or warmer.
Prospects for snow are paltry. So far we have seen a scant .9″ of snow, well below the 9.3″ we have on average by now. The long range outlooks (10 day forecast) from both the GFS (above image) and European model (below image) indicate we won’t need the shovels any time soon. The GFS spits out .6″ and the ECMWF just .1″.
There is cold and snow out there. Just over 60% of the continguous US has snow cover. There are wind chill advisories in effect for parts of North Dakota, Minnnesota, and northern Iowa where wind chills could dip to 35° below. We will get grazed by a snow system to the south that could squeeze out flurries or light snow across our southern suburbs today. We will also be on the bottom fringes of the Arctic air mass that is bringing the chill to the northern plains. We feel the effects of that tomorrow with the coldest day of the season so far. Aside from that, the next at least seven days look to be quiet and not too terribly cold with very little snow.
Sunday’s official high temperature of 33 degrees at O’Hare International Airport stands as a milestone in Chicago weather history. It marks the 309th consecutive day on which the city’s high temperature rose to at least 32 degrees, surpassing the long-standing record of 308 consecutive days at or above 32 degrees recorded in 1878. With luck, Monday’s high temperature will extend the consecutive string to 310 days, after which the bottom drops out and temperatures plunge on the first day of the new year.
Snow misses Chicago again
It’s yet another disappointment for Chicago’s snow-lovers. The latest snowstorm to pass through the Midwest has its sights on central and southern Illinois on Monday into early Tuesday.
When I was a kid I lived in Countryside and the weathermen would talk about the “boonies,” which was appropriate for Countryside, but I don’t hear that term anymore. Where are the “boonies” and the “super boonies” now, considering that the city area has expanded so much?
— Frank Dudek, Huntley, Ill.
“Boonies” is a colloquial shortening of the slang “boondocks,” which refers to remote, undeveloped and rural areas well away from urban centers.
John Coleman, a popular TV weathercaster on Chicago stations WBBM-Ch. 2 and WLS-Ch. 7 in the 1970s and early ’80s often used “the boonies” (with considerable exaggeration) to refer to Chicago’s suburbs. Ultimately, “super boonies” came to describe the area’s most outlying but unspecified locations.
As 2012 draws to a close, the season’s coldest air to date is heading toward Chicago. Temperatures on New Year’s Day are likely to be the coldest of what has been a relatively mild and snow-free winter. But, as has been the case with this winter’s cold spells, this one is to be short-lived. Following cold readings midweek – and “cold” only of moderate intensity – a gradual warm-up that takes hold on Thursday will continue into the weekend.
Chicago’s “snow drought” is forecast to continue through the week: At best, the seven-day period will bring only a little light snow or flurries.
Saturday’s high temperature, 32 degrees, marked Chicago’s 308th consecutive day with temperatures of 32 degrees or higher. That ties a long-standing record established in 1878 (134 years ago). Sunday’s expected high in the upper 20s ends the string.