SWOP Weekly Weather Discussion

HEADLINE

Above normal temperatures will prevail for the next several days, although there are signs of a significant cool-down by the end of next week. 

DISCUSSION

A west-to-east zonal flow pattern will remain in place across the U.S. through the upcoming weekend...resulting in a continuation of above normal temperatures.  Near seasonal highs in the middle 50s are anticipated initially, warming into the upper 50s and lower 60s by Friday, November 15th through at least early next week.  A short-wave trough embedded within the flat flow pattern will quickly traverse the country and skirt through Illinois on Wednesday, November 13th.  Scattered showers will accompany this feature with rainfall totals of 0.10 to 0.25 across much of central Illinois...and slightly higher amounts of 0.25 to 0.50 focused along and east of I-57.  Once the wave passes, a return to mild and dry conditions is expected by the end of the week.

Further out, both the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) are progged to go weakly negative, suggesting the potential for a surge of colder air making its way southward through Canada by the end of next week.  Models are in general agreement of this process, but have varying solutions concerning the timing and exactly how cool it may get.  With a more amplified upper pattern expected as per the negative phase of the NAO, confidence is increasing that another cut-off low will form over the Desert Southwest then begin pivoting northeastward toward the Midwest as the week progresses.  Since these cut-off systems do not typically tap into the Arctic air to the north...and there is little to no snow cover across the southern provinces of Canada, it seems reasonable to surmise that central Illinois will only see a glancing blow of chilly air by the end of next week.  We will need to keep an eye on how the process unfolds, as the approaching upper low could potentially trigger strong thunderstorms across parts of the Midwest during the Tuesday through Thursday time-frame of next week.      

The latest 6-10 day outlooks (Nov 16-20) from the Climate Prediction Center (CPC) suggest ABOVE normal temperatures and ABOVE normal precipitation across central Illinois.

Issued: 11/10/24