temperature

January 3, 2011

2010 Temperature and Precipitation in Illinois

Updated January 16 to include graph of monthly precipitation departures.

Based on preliminary data, the statewide annual temperature for Illinois in 2010 was 52.8 degrees, 1 degree above normal. Even so, the winter months of January, February, and December were much below normal. See bar graph below.

Precipitation

The statewide annual precipitation for Illinois in 2010 was 40.32 inches, 1.09 inches above normal. This was far less than the 50.46 inches in 2008 and the 51.02 inches in 2009. Of course the precipitation in 2010 was not evenly distributed throughout the state. Western Illinois experienced much above normal rainfall with amounts in excess of 48 inches in some areas. Meanwhile southern Illinois struggled with drought through much of the summer and fall. Below are the maps of total precipitation and departures from normal.

The 2010 precipitation total for Illinois.

2010 precipitation departure for 2010 — The 2010 precipitation departure from normal for 2010.

December 1, 2010

Warm November in Illinois

November

The statewide average temperature for November 2010 was 43.4 degrees, which was 1.6 degrees above normal. That makes it the 26th warmest November since statewide records began in 1895.
By the way, the 2000’s are well represented in the list of warm Novembers. Their rank and year include: #1 (2001), #5 (2009), #10 (2004), #14 (2003), #16 (2005), and #17 (2006).
The statewide average precipitation for November was 3.2 inches, only 0.1 inches below normal. November was exceptionally dry until the long Thanksgiving weekend arrived. Rains from that period signaled the recovery of soil moisture around the state. See the earlier posts on this subject.
The highest monthly total precipitation in Illinois for November was 7.15 inches recorded at Mt Carmel. The highest daily temperature for November was 82 degrees recorded at Cairo on November 13. The lowest daily temperature for November was 12 degrees recorded at Mt Carroll on November 26.

Fall

The statewide average temperature for fall (September-November) was 55.4 degrees, 1.2 degrees above normal.
The statewide average precipitation for fall was 8.6 inches, 0.8 inches below normal. Widespread rains in early September and late November masked the long period in between with dry conditions.
Note: these numbers are preliminary and subject to change as more data arrives.

November 18, 2010

Updated Forecast for December and Winter

NOAA’s Climate Prediction Center has come out with a new forecast for December and for December-February (winter). This is part of their routine update cycle.

December

The outlook for December in Illinois calls for an increased chance of above normal temperatures. An increased chance of above normal temperatures translates into just a few degrees above normal. Temperatures in Illinois have run an average of 2.9 degrees above normal for every month since March of this year. Therefore, continuing with a forecast for above-normal temperatures is not surprising.
The outlook calls for equal chances of above, below, or near-normal precipitation (or equal chances as they call it) in December in Illinois.

December-February (winter)

The outlook for December-February remains the same as last month. There is an increased chance of above-normal precipitation for all of Illinois. And, there is an increased chance of above-normal temperatures for the southern two-thirds of the state. See the figure below for more details.

CPC forecast — NOAA's Climate Prediction Center forecast for December and December-February (click to enlarge).

October 21, 2010

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