29. A new winter storm is forming, one low pressure coming out of WY, the other in the TX/OK panhandles.
The two low pressures will begin to phase into an elongated area over the Western Great Lakes by Saturday evening. The southern low will be able to bring up some Gulf moisture, adding some fuel to the fire. Precipitable water values (PWATs) over northern Wisconsin will reach 3/4", quite high for the time of year. Cold air behind the system (a high temp of 6 in Devil's Lake, ND on Saturday) will be butting up against warm air to the southeast (a high temp of 47 in Peoria, IL on Saturday), forming quite a temperature gradient.
Forecast computer models have taken an abrupt change in the last 24 hours, strengthening the system and bringing it a little farther west. Since the low pressures are only forming now (Friday morning), everyone across the region will be watching the system closely -- there is still time for more changes to occur.
Current Snow Forecast
The heaviest snow band is expected to run N/NE to the S/SW from the UP of Michigan to Iowa. In the northern part of that band there is potential for over 6 inches of snow (maybe up to 9" with some Lake enhancement), while towards the south 3-6" are more likely. On either side of that band amounts will be lower.
Winter Storm Watches
Winter Storm Watches are beginning to be posted from the Arrowhead of MN down through IA. More counties may be added to the current Watches, and fine tuning of the forecast will occur throughout the day. In the first map, all the blue counties are under a Winter Storm Watch.
Synopsis and Low Track
The northern low pressure is already emerging and organizing over western North Dakota. Within several hours it will have it's act together and consolidate. The southern low pressure will emerge from the Southern Rockies later today and organize over the Texas and Oklahoma panhandles. Such a system is often called a Panhandle Low and makes a hook to the Great Lakes. The map (to the right) shows the expected tracks the lows will take. The southern low will be the dominate one with the most moisture and will deepen as it tracks north.
This is just our first look at the system.
All of this is preliminary, since this storm system is only organizing now. I'll update more later, especially when new data becomes available.