29. Confidence is high enough to begin issuing Snow and Winter Weather Advisories.
At this time it looks like 3 to 7 inches will fall across the northern part of the state, 1 to 3 across the central areas, and some freezing rain early in the Fox Valley and Door County.
The map compilation (to the right) are screenshots I took from NWS Offices in Duluth, La Crosse, and Green Bay, showing current advisories. On top of these maps I super-imposed expected snowfall totals. Each office's website will give up to-date information.
Models are starting to agree.
NWS Duluth is using the NAM for timing of the system, but agreement is close between all the models. The map (to the left) is from the HPC and shows the forecast track of each low pressure.
The orange color low over Iowa is the forecast position at 18:00 on Monday. The brown color low over Sault Ste. Marie is the forecast position at 0:00 on Tuesday.
The forecast calls for steady strength of the low pressure, which would keep us from getting too much snow.
The latest run of the GFS is showing the heaviest snow over northern Wisconsin.
The map (to the right) is from the NCEP and shows the forecast at 30 hours, about 18:00 on Monday.
The Quantitative Precipitation Forecast (QPF = green shading) fields show where the heaviest precipitation is expected, across northern Wisconsin, which is where the advisories have been issued.
Also, the rain/snow line is showing up from Green Bay to La Crosse. North of this line would be mainly snow, while south would remain warm enough for rain or a mix. East-central Wisconsin may see some freezing rain and central Wisconsin should see mixed precipitation with some snow.
Temperatures across the north will be near 32 degrees on Monday afternoon. By Tuesday morning temperatures will have fallen to the upper-teens or lower twenties as Canadian high pressure builds quickly in behind the departing low pressure.
Luckily, the models are showing the arctic air will stay up in Canada for the rest of the week. One model is hinting that some cold may work south on Friday, while the others are waiting until the following week.
NW Wisconsin Weather Blog
For more information concerning the area to my southwest (Polk, St. Croix, Dunn, Barron, Burnett, and Washburn counties), see Derek's NW Wisconsin Weather Blog.