(4:00PM - 11/22/19) A storm system is expected to move across the region tonight into Saturday, which will affect portions of the state during this time.
As was outlined in our original post from Wednesday night, "Potential Weekend Accumulating Snow?", model guidance was showing a storm system potentially affecting the state during the time-frame of tonight into Saturday. Model guidance was significantly struggling with this system and the overall pattern, in a complex setup. Two scenarios were outlined in the original post...
#1... The southern stream disturbance is slower at ejecting out into the Plains, with a northern stream disturbance digging into the Northern U.S. This would allow for partial phasing to occur, thus a more pronounced storm system with the potential for at least a couple inches of snow within a swath across the heart of the state.
#2... The southern stream disturbance is faster and ejecting out, misses a partial phase with the northern stream disturbance, and is instead sheared out. This would lead to a very weak storm system, with little to no chance for snow across the state.
At the time of the original post, model guidance was fairly split between both scenarios, but slightly favored scenario #1...which resulted in the need for a post outlining the potential, especially given it was only 2-3 days away. Since that time, model guidance continued to struggle for a while, before finally coming into agreement on the original outlined scenario #2. With all of that said, a storm system is still expected to move across the region tonight into Saturday. Rain showers will be possible across Central and Southern Illinois during this time. With some cold air in place, some snow showers will be possible across Central Illinois and vicinity. Little to no snow accumulation is expected. This will likely be the last update regarding this storm system.