“The Edge of Drought” sounds like a soap opera or a catchy book title. However, southern Illinois is on the edge of a much larger drought in the southern US. The US Drought Monitor just released their latest map on Thursday, showing some of the southernmost counties in D1 (moderate drought). Other areas of Illinois are labeled D0 (abnormally dry).
The NWS Climate Prediction Center released their latest outlooks for December, winter, spring, and summer. La Niña conditions are present and slightly favored to persist (~55% chance) through winter 2016-17. It is one of many players in our winter weather. Click to enlarge.
Illinois has equal chances (EC) of above, below, and near-normal precipitation and temperatures.
With the streak of warm weather this fall, thoughts of snow are far away – but not for much longer. The first significant winter storm for the Midwest is on the horizon on Thursday and Friday. It will likely hit Nebraska, the Dakotas, and Minnesota, but miss Illinois (blue shading on the map below).
So when can we expect to see that first measurable snowfall (0.1 inches or more) in Illinois?
Here is a map that we constructed a few years ago using data from 1971-2000. No surprise – the earliest dates are in the Chicago area and cluster around November 20. For the rest of the northern half of the state, the average date is towards the end of November. In central Illinois, I have always considered Thanksgiving to be the start of the snowfall season. The average dates get dramatically later as you go southward, getting closer to Christmas by the time you get to Carbondale and southward.
Normally I write about Illinois, but the warm, dry weather experienced across Illinois so far in November covers a much larger area.
Here are the temperature departures from normal across the US. Almost all of the US has experienced well above-normal temperatures (except the East Coast). Illinois has been running about 8 degrees above normal. However, the temperature departures in the upper Midwest and the High Plains are 9 to 15 degrees above normal. The NWS forecast indicates that this pattern of warmer temperatures will persist for the rest of November.
November so far has been 11 degrees above normal for Illinois. The temperature departure map for November below has a “shades of cranberry sauce” theme appropriate for Thanksgiving. Temperature departures for November 1-6 range from 8 to 14 degrees above normal across the state.
The statewide average temperature for October in Illinois was 59.8 degrees, 5.4 degrees above normal and the 7th warmest October on record.
The statewide average precipitation for October in Illinois was 2.38 inches, 0.86 inches below normal. There were a few bands of 3 to 5 inches across northern Illinois and along the Interstate 70 corridor (left panel). Outside of those areas, October was drier than normal (right panel). The site with the largest monthly rainfall total was Palos Park, in Cook County, with 5.51 inches (IL-CK-50).