Tuesday Night Outlook
Text From The RACES Tuesday Night Net:
A cold front swept through northern Illinois this afternoon, dropping temperatures into the mid-40’s. Temperatures will stay in the mid-40’s for Wednesday, then warm up a little into the mid-50’s on Thursday, and even higher on Friday into the mid-60’s. High temperatures over the weekend into the beginning of next week will stay in the mid- to upper 50’s.
Wednesday will bring light showers and thunderstorms in the afternoon. There will also be a chance of showers and thunderstorms Thursday night, Friday night, and Saturday night.
Detailed Forecast Discussion:
Temperatures will generally be on the decrease through Thursday as easterly winds set in across the region. A deep layered trough currently over the Pacific will propagate across the Rockies through mid week and reach our neck of the woods late on Friday. Out ahead of this system, warm air advection will kick in and we will start to see a gradual warm up for the early portion of the weekend with winds shifting to more of a southerly component. A shortwave trough propagating through the mid-level flow will spin up a surface low that should move through northern Wisconsin late Friday into Saturday. Some showers and thunderstorms will be possible out ahead of this front, but the main show comes in on late Saturday and into Sunday as the upper level trough moves into the upper Mississippi Valley. A surface low will develop Saturday morning in response to the upper low in eastern Oklahoma and rapidly move northward into eastern Iowa by Saturday afternoon. With this low originating near the Gulf, it will likely draw more moisture up with it as it moves up along the Mississippi River. So, have bumped up POP’s a bit from Saturday afternoon into Sunday. The European and the GFS are still differing a bit with the position of the low, but the timing seems to be there. The Euro wants to originate it a bit further west and then occlude in into the eastern Dakotas, while the GFS brings it right up the Mississippi and occludes it into Wisconsin. For this forecast, pretty much split the difference on the low position since the timing seems to be reasonable. The GFS would mean a wetter solution for us, but regardless, the Gulf will be open and plenty of moisture should be available for use. With this being a Pacific system, there is not too much of a cool down on the backside of the low.
Another shortwave trough will move across the Dakotas on Monday, which will bring another brief warmup on Monday, and while there will be some precipitation generated from this, the main story may be the fact that low temperatures may touch the freezing mark toward midweek for the first time in about a week and give us a gentle
reminder that it still is March.
