1.31″ of precipitation (and 8.9″ of snow) fell during the month of January. Snowfall was 1.2″ below the average snowfall of 10.1″ in the month of January, and 0.58″ of precipitation below the January average of 1.89″.
This is consistent with El Niño conditions that dominated the month, causing most of the nation’s precipitation to be redirected to California, the Gulf Coast, and the Eastern Seaboard.
A winter storm is expected to bring 3″ to 6″ of snow to the area Monday night. However, there is a chance the storm will bring over 6″ of snow to the area.
Up to an inch of rain is expected to fall this weekend. Combined with temperatures in the 40s and a melting snowpack, low-lying areas will likely flood as a result.
Monitor the latest forecasts at http://www.crh.noaa.gov/lot for the latest information. The latest hydrologic outlook is posted below.
HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO IL
545 AM CST SAT JAN 23 2010 /645 AM EST SAT JAN 23 2010/
...RAIN AND SNOW MELT COULD PRODUCE FLOODING THIS WEEKEND...
AN ENERGETIC STORM SYSTEM NOW LOCATED OVER THE SOUTHWESTERN UNITED
STATES WILL DEEPEN AS IT REACHES THE MID MISSISSIPPI VALLEY BY EARLY
SUNDAY MORNING. THIS LOW PRESSURE WILL THEN CONTINUE NORTHEASTWARD
TO NEAR CHICAGO BY NOON SUNDAY. AS THIS SYSTEM APPROACHES...RAIN
WILL INCREASE IN COVERAGE AND OVERSPREAD NORTHERN ILLINOIS LATE THIS
AFTERNOON AND NORTHWEST INDIANA THIS EVENING. RAIN MAY BECOME HEAVY
AT TIMES LATER TONIGHT THROUGH MID DAY SUNDAY AS THE STORM CENTER
PASSES OVER THE AREA.
RAINFALL OF AROUND AN INCH MAY FALL IN WIDESPREAD COVERAGE BY SUNDAY
AFTERNOON. IN ADDITION...1 TO 5 INCHES OF COMPACT SNOW REMAINS ON
THE GROUND IN NORTHERN ILLINOIS AND NORTHWEST INDIANA. THE RAIN AND
SNOW MELT MAY COMBINE TO PRODUCE ENOUGH RUNOFF OVER FROZEN GROUND
TO QUICKLY RAISE AREA RIVER LEVELS TO FLOOD STAGE.
FLOODING OF CREEKS...STREAMS AND PONDING OF WATER IN LOW LYING AREAS
MAY ALSO OCCUR.
$$
MERZLOCK
2009 was a wet, cold year for the Chicagoland area. 47.44″ of total precipitation, and 51.6″ of snow, fell in the calendar year for 2009. This is about 11″ more precipitation than the yearly normal of 36.27″ at O’Hare International Airport, and 13.6″ more snow than normal.
This is, however, less than the 50.45″ and 60.2″ of rain that fell in calendar year 2008.
The dry start to January is offset by 4.62″ of precipitation that fell during December, more than twice the normal amount (2.15″). Much of the precipitation fell as snow, and remains as snowpack, helping to cool daytime temperatures.
Another 7-9″ of snow (0.30″ water equivalent) is expected to fall on Thursday, January 7. With another surge of arctic air following the snowfall and models not predicting a pattern change for the next two weeks, 2010 promises to continue its cool trend.
A large, wet storm system will bring heavy rain to the area starting Christmas Eve and extending beyond Christmas Day. Up to 1.50″ of rain is expected to fall on frozen ground, melting the snow and producing potentially excessive runoff.
This is a repeat scenario of last year’s late December storm, when 2.00″ of rain melted 2 inches of water frozen in the snowpack. However, last year’s snowpack was much greater than this year, and forecast rainfall amounts are currently less than last year.
Flooding of low-lying areas into the weekend is still possible.
For the month of October, 6.51″ of rain fell in Carol Stream. This was 3.84″ above the normal total of 2.67″, or 244% from normal. Rain was observed on 23 of 31 days.
Fortunately, long-term forecasts call for less rain through mid-November. In addition, the large amount of rain fell gradually, causing only limited flooding problems.
Very heavy rain leading to flooding, severe storms and strong winds may occur Thursday night into Friday, according to the National Weather Service.
The ground continues to be very saturated because of rains that have fallen over the past 6 days, totaling 2.42″. A heavy rain event will lead to flooding.
The level of Lake George has fallen since Saturday, and is no longer flowing into the northern detention basin.
As of 10:30 this morning, the 4-day total rain total had reached 2.04″. Rain will continue through this coming week, causing another 1 to 2 inches to fall on the area. This may cause minor flooding.
Lake George is currently overflowing into northern-most dentention pond. Some benches normally along the shoreline of the lake are partially underwater.
A 0.62″ rainfall yesterday and through the night broke a very dry streak of 0.04″ of rain through the first 19 days of September. The brings the September rainfall total to 0.66″.
Fortunately, August 2009 was a wet month in Carol Stream. A total of 5.01″ of rain fell in August, 1.38″ more than the monthly average of 3.63″ (+38%).
As of 7:30 pm, a total of 1.62″ has fallen in Carol Stream. 0.03″ fell between 8:00 this morning and 7:00 tonight. This amounted to an 11-hour break from rain. The following is a status of the flood-control structures in the area:
- Lake George (the main retention pond in Armstrong Park) is over bankfull
- Klein Creek is about 75% full
- West Branch of the DuPage River at Schick Road is almost over its banks
- Area retention ponds are largely barely full
A very, very slow moving low-pressure impulse will move into the Carol Stream area tonight and tomorrow, raising the possibility of widespread flooding in the region. A Flash Flood Watch remains in effect through tomorrow afternoon.
After showers and scattered rain today, the ground remains saturated after nearly 1 3/4″ of rain. A further 3-4″ of rain may be possible overnight tonight, resulting in flooding. The risk of flooding is considerably greater north of the Elgin-O’Hare Expressway and west of Illinois 53, where widespread rain totals of 2-3″ have already occurred. However, tonight’s heavy rainfall threat is likely to be more widespread than today’s heavy rainfall.
