SWOP Weekly Weather Discussion

HEADLINE

Sharply colder conditions will arrive across central Illinois for Thanksgiving...with the potential for accumulating snowfall by the weekend.

DISCUSSION

A vigorous short-wave trough over the Northern Rockies will dig southeastward over the next couple of days...sending a strong cold front through central Illinois during the evening of Tuesday, November 25th.  While temperatures ahead of the front will climb well into the 50s on Tuesday, strong northwesterly winds gusting 35-45mph will send readings plunging into the upper 30s and lower 40s on Wednesday.  While the strong winds will begin to ease by Thanksgiving Day, much below normal highs in the middle to upper 30s are anticipated.  After that, all computer models are suggesting another short-wave trough will drop into the region during the night of Friday, November 28th into Saturday, November 29th.  The atmosphere will initially be cold enough for snow, with readings expected to warm sufficiently during the day Saturday to support a transition to a rain/snow mix.  It is still too early to pinpoint exact accumulations: however, confidence is growing that the first widespread snow accumulation will occur across most of central and southeast Illinois.  While this does not appear to be a major snowstorm, travelers are urged to pay attention to future forecasts as the potential exists for travel concerns...particularly late Friday night into early Saturday morning.  Behind this initial system, continued deep-layer northwesterly flow will ensure below normal temperatures into the first week of December.     

Both the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) are currently weakly negative and are progged to remain slightly negative or hover near neutral for the next week.  After that, models are suggesting the AO and NAO may become weakly positive...potentially suggesting a gradual climb back to near normal temperatures by the second week of December. 

The latest 6-10 day outlooks (Nov 30-Dec 4) from the Climate Prediction Center (CPC) suggest BELOW normal temperatures and ABOVE normal precipitation across central Illinois.

Issued: 11/24/25