Powerful Storm System Tonight through Friday morning
A strong potent Low Pressure system is organizing in the Rockies this morning and will track northeast through the northern Great Lakes through Friday afternoon. As it does, it will spread a late season winter storm across portions of Nebraska, South Dakota, Minnesota, and Wisconsin. Meanwhile, severe thunderstorms will be possible to the south from Kansas to Indiana. This system will bring windy conditions with gusts over 50 MPH at times, which will result in blizzard conditions for areas that receive snow. This snow storm would be impressive regardless of the time of year, so for it to be occurring in April makes it even more remarkable. Many areas will receive 12-24" of snow, with local amounts up to 30". The NWS snowfall forecast through 7PM Friday at the 75th percentile is shown below.
This system won't bring significant snow to Mid-Michigan, but we are still expecting a wide variety of impacts beginning this evening and continuing through Friday morning. These impacts include a little snow, wind, rain, and possibly thunderstorms as well. Here's the timing breakdown:
A mixture of rain and snow showers will arrive after 6-7PM this evening moving from south to north. Since temperatures should be just above freezing, accumulations are anticipated to be on mainly grassy surfaces, although wet and slushy roads are a concern. Most areas will see 1" or less of snow accumulation.
Most of Thursday will be dry with only an isolated chance of a rain shower. Winds will be gusting over 30MPH out of the east with highs hovering around 40. Thursday Night, winds shift to the south, which actually causes temperatures to warm to near 50 by sunrise Friday with showers and thunderstorms developing overnight. A threat for severe weather exists to the SW of mid-Michigan. The following image shows a marginal risk in southwestern lower Michigan. Instability should be weak given the overnight setting, so the severe potential looks low.
Rain will move out by early afternoon on Friday and highs will be in the 50s as a strong SW wind develops during the afternoon. Southern sections may reach the lower-60s. Cooler weather returns for Saturday and Sunday as another system approaches. Sunday into Sunday night looks wet with a light rain event 12-18 hours in duration. I also believe that some snow may mix in with the rain at times. Snow accumulations appear possible with the northwestern extent of the precipitation, but the track of the system and actual temperatures will be key in finding the position of the rain/snow line. Notice the potential for snow to mix in showing up on the GFS computer model in the image below. It may not seem that impressive here, but this is just one run and one example. I'll be watching this closely as the weekend approaches.