As most of you probably feel by now, winter has returned quite impressively over the last 12 to 18 hours across the Midwest, including here in Illinois. Much colder temperatures along with windy conditions have been common behind the frontal passages yesterday afternoon and evening and into early this morning. As was discussed the other day, the pattern looked to be changing to one that could bring multiple snow systems to the region and through portions of Illinois. Well, the first one is on the way for Sunday and will mainly affect the northern half of the state with accumulating snow.
I'll dig into this system along with timing and potential snowfall amounts below...
Our Sunday snow maker is still out over the Pacific Ocean early this Friday morning but will continue in the direction of the west coast and eventually come ashore southern California on Saturday morning. This will be a fairly low amplitude wave and a fast moving system at that, quickly jumping the Rockies and emerging into the plains by early Sunday morning. Below, you can see the path our system will take as it begins to approach the region from the west. The image is valid at 9am on Saturday morning, showing the wave moving through the southern part of California.
As our system crosses the Four Corners region and the Rockies, an area of low pressure will develop across eastern Colorado, leading to winds responding and strengthening across the southern and central plains Saturday afternoon through Sunday morning. This wind response will be what drives the development of precipitation off to our west and southwest late Saturday night. Strong warm air advection (marked in red below) will help aid in a fairly widespread area of precipitation by early Sunday morning to our west.
As previously mentioned, a broad area of snow will develop across portions of Kansas, Iowa and Missouri late Saturday night and into Sunday morning and then continue east and northeast through all of Iowa and into about the northern half of Illinois, favoring the northern portion of the state at this time. Temperatures will be in the mid 20's as it looks now for most of this event which means snow should stick and accumulate fairly easily once it begins from west to east on Sunday morning.
This will not be a big winter storm by any means but this system could produce several inches of snow across portions of the northern half of the state where it will be more than cold enough for accumulations. Further south across southern Illinois, temperatures will be too warm with this being a mostly rain event and possibly a period of mixed precipitation. Updates will continue on this system over the next 48 hours, along with fine tuning the snowfall forecast for expected totals on Sunday.
Below is our first TAM snowfall forecast for this system.