Public weather briefingDiminishing clouds during the afternoon will lead to a cool night across the area tonight. Temperatures drop back into the mid 30's with clear skies and light winds out of the southwest. Attention turns to a developing area of low pressure currently entering the US in northern Montana. This system will continue to dive southeastward Wednesday night into Thursday. The precipitation will begin as rain mainly after 6pm tomorrow, but should transition over to a wintry mix overnight, with a chance for snow showers by Thursday morning as the system passes to our east. Highs Thursday will be significantly cooler, struggling to reach 40 with brisk northwesterly winds approaching 20mph. A relatively dry cold front moves in Saturday morning, accompanied by well below normal temperatures, with highs in the upper 30's both Saturday and Sunday. Significant winter weather is possible as we head into the next work week.
Tonight. Mostly Clear. Low 35. Southwest winds at 5 to 10 mph.
Wednesday. Increasing clouds. PM rain showers. High 55. Southerly winds around 10 mph.
Wednesday Night. Rain, changing to a wintry mix. Low 35. South wind 5-10mph, shifting westerly during the overnight. Precipitation amounts around a tenth of an inch. Little snow accumulation expected.
Thursday. Morning show showers. Cloudy skies, high around 40. Gusty winds out of the north at 15 to 25 mph.
Friday. A few passing clouds. High around 43. Winds light and variable
Outlook for Saturday through Monday. Slight chance of precipitation Friday night into Saturday. Unseasonably cold Saturday and Sunday, highs around 40. A strong area of low pressure looks to impact the Great Lakes Monday into Tuesday, with accumulating snow possible. [CONFIDENCE: LOW]
The next significant cyclone pushes in for Wednesday into Thursday as a strengthening area of low pressure drifts southeast from southern Canada. Localized warm air advection ahead of the system will warm us up into the mid 50's and suggest upward vertical motion. The GFS is outputting significant Q vector convergence along the track of the system. Consequently, vertical motion can be expected and is forecasted by both the NAM and GFS. Both models have a chance of showers late Wednesday evening ahead of the passing cyclone. As the cyclone pulls away from Southern Wisconsin, cold air advection will result from the shifting of winds on the back side. While there is cold air advection, it is not localized. A significant amount of positive vorticity advection is forecasted by the NAM and GFS, which will spawn the chance of snow showers with light accumulations, as 850mb temperatures are below zero and 1000-500mb thickness values drop to 5340 meters. The GFS plots upward vertical motion directly over Madison Thursday morning.
Furthermore, here is the 12z ECMWF snow output for the Monday possible winter storm, can we all gasp out a collect "WOW":
And the 18z GFS:
Courtesy of Weather bell.