SWOP Weekly Weather Discussion

HEADLINE

A blast of cold air will arrive by early next week...possibly providing the first snowflakes of the season to parts of the area.

DISCUSSION

A relatively flat west-to-east zonal will be in place across the U.S. for the next couple of days...allowing the continuation of mild fall weather.  Meanwhile a short-wave trough evident on the latest water vapor imagery just northwest of Hudson Bay will dig southeastward, pushing a cold front toward central Illinois by Friday, November 7th.  Southwesterly flow ahead of the approaching boundary will send high temperatures into the upper 60s and lower 70s.  A few showers will accompany the front: however, rainfall amounts will mostly remain under 0.10.  Once the front passes, a return to seasonal temperatures in the upper 50s and lower 60s is anticipated for Saturday.  After that, a second short-wave dropping southward out of Canada will carve a significant trough over the Midwest/Great Lakes by early next week.  Low pressure associated with this wave will bring rain showers Saturday afternoon and evening...with a few snow flurries or light snow showers possible along and north of I-74 by Saturday night into Sunday morning.  No snow accumulation is expected.  Aside from the flurries, the main weather story will be the windy and sharply colder weather.  High temperatures on Sunday, November 9th and Monday, November 10th will struggle to reach the upper 30s and lower 40s, while overnight lows dip into the upper teens and lower 20s.

Both the Arctic Oscillation (AO) and North Atlantic Oscillation which are presently neutral are forecasted to go negative over the next few days...highly supportive of an amplified upper pattern and a resulting cold surge from the North Pole.  By later in the priod, both parameters are progged to rise back toward neutral territory...suggesting the cold wave will be short-lived.  Medium range computer models agree...and generally show a return to warmer than normal temperatures by the end of next week.  

The latest 6-10 day outlooks (Nov 10-14) from the Climate Prediction Center (CPC) suggest BELOW normal temperatures and BELOW normal precipitation across central Illinois.

Issued: 11/5/25