December 2011 – Illinois State Climatologist

December 21, 2011

December – Warmer and Wetter in Illinois So Far

Precipitation and Temperatures in December for Illinois

Based on data through December 21, the statewide average precipitation was 2.9 inches, 1.1 inches above average.
The statewide average temperature was 35.6 °F, 4.5 °F above average. That stands in stark contrast to last December when the average temperature was 21.8 °F through this date. Put another way, we are about 13.8 °F warmer this December than last December through the 21st of the month.

Where is the snow?

With the warmer temperatures this December, we have seen lots of rain but not much snow. The two maps show the snowfall for the period of December 1-21, 2011 and the same period for December 2010. Snowfall is lacking throughout much of the Midwest except for the one winter storm earlier this week. Southeast Illinois has reported no snowfall in December while much of the rest of state has seen two inches or less. By this time last December (second map), much of Illinois and the upper Midwest had experienced 10-25 inches of snow.

December 2011 snowfall — December 1-21, 2011 snowfall. Click to enlarge.

December 2010 snowfall — December 1-21, 2010, snowfall for the Midwest.

December 16, 2011

Odds of a White Christmas in Illinois

We just updated the odds of a white Christmas in Illinois, based on 1981-2010 data. We created the map using stations that had at least 20 years of snowfall data during the 1981-2010 period. A year with a white Christmas was defined as having measurable snow on the ground on December 25.
There can be large differences from site to site. Snowfall is notoriously difficult to measures with two nearby sites having different results due to exposure to sun and wind. In general, the odds are about 40-50 percent in the northern third of Illinois, 20-40 percent in central Illinois, and 0-20 percent in southern Illinois.

December 15, 2011

NWS Outlook for January – Warmer and Wetter than Average

The NWS released their new monthly and seasonal outlooks today. For January they are calling for an increased chance of above average temperatures for Illinois. Much of Illinois has an increased chance of above average precipitation as well.
The January-March outlook for Illinois is for an increased chance of above average precipitation and above average temperatures.
If you were not looking forward to a repeat of last year’s winter, this is good news. An increased chance of above average temperatures does not mean you will be playing golf in Illinois in mid-January. But it puts you in better shape than January 2011, which came in at 3 degrees below average.
Why the more upbeat forecast? The current La Niña event occurring in the Pacific has been much weaker than expected, and forecasted to stay so for the rest of the winter. These new forecasts for temperature and precipitation reflect the weaker La Niña event. As noted in an earlier post, November was the sixth wettest and ninth warmest on record. And the first half of December has been above average on temperature and precipitation in most locations.

NOAA outlooks for this winter. — NOAA outlook for January and January-March. Click to enlarge.

December 14, 2011

Extreme Weather Year in the US

This year has been noteworthy for the number of extreme events across the U.S. In fact, we have had 12 disasters that have exceeded $1 billion in losses each in 2011. We also experienced some $50 billion in total losses for the year. And that is with a fairly quiet hurricane season. Some of those billion dollar disasters had direct impacts on Illinois, including the February blizzard, and the spring flooding.
You can read more about the major disasters this year at http://www.noaa.gov/extreme2011/
NOAA is promoting a new concept called a “Weather Ready Nation”. The idea is to be better prepared and to better respond to weather/climate disasters. This involves better forecasts, better dissemination of forecasts, and closer working relationships among federal, state, and local partners. I’m sure we will hear more about this in coming months.
[Update: The method used to generate the bar-plot part of this graph is apparently flawed. While the line plots show both actual damages and damages adjusted for the Consumer Price Index, they did not make a similar adjustment on the number of 1 billion dollar event. As a result, the number of 1 billion dollar events will climb as prices climb (for example, the destroyed $100k home in 1980 would be worth $250k in 2011). See http://rogerpielkejr.blogspot.com/2012/01/bad-economics-at-noaa.html.]