Tag: Chicago

Posted on

Late Season Snowfall in Chicago and Rockford

Gino Izzi of the NWS office in Romeoville rounded up these statistics for late season snowfall in Chicago and Rockford…

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
1128 AM CDT FRI MAR 25 2011 /1228 PM EDT FRI MAR 25 2011/
...LATE SEASON SNOWFALLS...
NOTHING SAYS SPRING TIME IN ILLINOIS MORE THAN TEMPERATURES IN THE
20S AND GRAY CLOUDY SKIES...BUT HISTORICALLY SPEAKING IT MAY BE A
BIT TOO SOON TO STOW AWAY THOSE SHOVELS. IN FACT...PORTIONS OF
MISSOURI AND DOWNSTATE ILLINOIS ARE SEEING SNOW THIS MORNING. SO
HOW COMMON IS IT TO SEE SHOVEL-ABLE SNOW IN OUR AREA THIS TIME OF
YEAR?
IN CHICAGO...54 OF THE PAST 139 YEARS (OR ABOUT 39%) HAVE HAD AT
LEAST ONE DAY WITH AN INCH OR MORE OF SNOWFALL ON OR AFTER MARCH
25TH. IN FACT...17 OF THOSE YEARS HAD MULTIPLE DAYS WITH OVER AN
INCH OF SNOWFALL INCLUDING 6 DAYS WITH OVER AN INCH OF SNOW BACK IN
1926! HERE ARE SOME OF THE RECENT LATE SEASON (AFTER MARCH 25TH)
CHICAGO SNOWFALLS...
SNOWFALL    DATE
 3.0     4/11/2007
 3.0     4/ 7/2003
 2.1     4/ 5/2009
 1.9     3/27/2008
 1.6     4/ 7/2000
 1.2     3/29/2009
HERE ARE THE TOP 10 BIGGEST LATE SEASON SINGLE DAY SNOWFALL TOTALS
FOR CHICAGO...
RANK   SNOW      DATE
 1    13.6    3/25/1930
 2     9.4    4/ 5/1982
 9.4    4/ 2/1975
 4     9.0    4/ 6/1938
 5     8.9    3/26/1970
 6     8.2    4/ 1/1970
 7     7.8    3/30/1926
 8     7.7    3/29/1954
 9     7.1    3/29/1964
10     6.6    3/26/1934
IN ROCKFORD...47 OF THE PAST 118 YEARS (OR ABOUT 40%) HAVE HAD DAYS
WITH AN INCH OR MORE OF SNOWFALL ON OR AFTER MARCH 25TH. OF THOSE
YEARS...10 HAVE HAD MULTIPLE DAYS WITH OVER AN INCH OF SNOW
INCLUDING 4 DAYS IN 1970 AND 1926. HERE ARE SOME RECENT LATE SEASON
ROCKFORD SNOWFALLS...
SNOWFALL    DATE
 1.9     4/11/2007
 1.8     3/29/2009
 1.2     4/ 7/2000
 1.1     4/ 1/2002
 1.0     4/12/2007
HERE ARE THE TOP 10 BIGGEST LATE SEASON SINGLE DAY SNOWFALL TOTALS
FOR ROCKFORD...
RANK   SNOW      DATE
 1    13.5    3/31/1926
 2    10.4    3/29/1972
 3     7.0    4/18/1912
 4     6.3    4/ 5/1982
 5     6.0    4/ 6/1938,  6.0    3/25/1933
 7     5.0    3/29/1954
 8     4.8    3/29/1964
 9     4.6    4/ 2/1975
10     4.5    4/ 2/1936,  4.5    3/28/1894
WHILE NO BIG SNOWS ARE CURRENTLY IN THE FORECAST FOR THE REGION...IT
IS WORTH NOTING THAT LATE SEASON SNOWS ARE NOTORIOUSLY DIFFICULT TO
PREDICT MUCH IN ADVANCE. CURRENT INDICATIONS ARE THAT THE COLD AIR
OVER THE AREA NOW WILL REMAIN IN PLACE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK.
$$
IZZI
Posted on

Impact of the February 1-2 Storm on Highways

The impact of the February 1-2, 2011, storm on highways in Illinois was significant. Using snowfall data and Illinois DOT highway data, our GIS specialist Zoe Zaloudek was able to calculate the number of miles of interstate, US highways, and state roads covered by selected amounts of snow.
Below is the resulting map showing both the roads and significant snowfall. A table at the bottom of the map shows the number of miles affected by 6, 8 and 12 inches or more of snow. The impacts were felt all the way from Quincy to Chicago. We chose a starting point of 6 inches as the threshold for significant disruption of traffic and higher removal cost, based on earlier studies in Illinois.
For example, about 1,132 miles of interstate roads in Illinois received 12 inches or more of snow. Including 1,762 miles of US highways and 4,099 miles of state roads, it adds up to an incredible 6,993 miles of roads with a foot or more of snow to plow.
These estimates do not include the thousands of miles of county roads as well as city streets and alleys in the Chicago metropolitan area and elsewhere. However, we did not have a complete database of those road systems. Also roads covered by less than 6 inches of snow were treated as well for additional costs.

February blizzard affect roadways
The number of miles of Illinois roadways affected by selected amounts of snowfall during the February 1-2, 2011, winter storm.

Posted on

Winter Outlook for Illinois – Wetter and Warmer

NOAA’s Climate Prediction Center released their official winter outlook today. The major influence in this winter’s weather will be the moderate to strong La Niña event occurring in the Pacific Ocean.

Precipitation

The winter outlook calls for an increased chance of above-normal precipitation across Illinois. They also state that the Ohio River Valley (including Illinois) is … “likely to see increased storminess and flooding.” Other studies have shown an increase in snowfall in the Great Lakes region during past La Niña events, especially in the January-March period.

Temperature

The southern two-thirds of the state has an increased chance of above-normal temperature. Meanwhile the northern third of Illinois has “equal chances” of above-, below-, or normal temperatures.  This basically means that their forecast tools are providing no guidance on winter temperatures in northern Illinois, including the Chicago area.
 

Winter outlook for precipitation (NOAA)
NOAA Winter Outlook for Precipitation.

 
 
winter outlook for temperature (NOAA)
NOAA Winter Outlook for Temperature

 

Posted on

October Temperature Swings in Chicago

Like most sites in Illinois, Chicago has experienced large temperature swings in October. The month started with below-normal temperatures on October 2-5. The departures were as large as 8 degrees below normal on October 3 and 4.
This cold period was followed by a period of much above normal temperatures on October 6-12. The departures were as large as 16 degrees above normal on October 9 and 10. In fact, the high of 86 degrees reported at O’Hare on October 9 tied the record set in 1962.
Slightly above-normal temperatures prevailed on October 13-18. The early cold period and later warm periods resulted in an average of 58.7 degrees for the first 18 days in Chicago, 3.9 degrees above normal.
 

chicago daily data october 2010
Day by day temperature departures from normal for Chicago Illinois in October 2010.