29. Advisories have been posted across the area for tonight and tomorrow. Then we have to watch wind chill values.
Surface analysis at 6:00 shows a low pressure center in southwest South Dakota with a series of fronts in-front of and behind it. The lowest pressure is currently around 986 mb (29.12 "Hg) and a forecast track that will take the low center just north of Lake Superior at 6:00 tomorrow morning.
First rain and then snow.
The map (above) is from the NWS in Duluth and shows all the Advisories and Watches for northeast Minnesota and northwest Wisconsin.
A Snow and Blowing Snow Advisory is in effect for the entire area through Tuesday at 18:00 and a Winter Weather Advisory covers northeast Wisconsin.
A Windchill Watch is in effect for Tuesday evening through Wednesday morning across Duluth's forecast area. If wind chills will be able to fall below -35, this may be upgraded to a Warning.
The map (to the left) is from the NWS's Graphical Forecast suite and shows expected weather at 4:00 on Tuesday. Rain is forecast between 18:00 and 0:00 tonight before turning over to a mix of precipitation before 6:00.
Around 6:00 on Tuesday the arctic front will blast through bringing a sudden drop in temperatures and period of moderate snow with stronger winds. Up to 2 inches of snow seems reasonable, but with strong winds, measuring how much may be difficult.
An excerpt from the advisories issued by the NWS in Duluth:
"MAJOR CHANGES WILL OCCUR THE MOMENT THIS ARCTIC FRONT ARRIVES. SKIES WILL SUDDENLY DARKEN AND A VERY BRIEF PERIOD WITH A WINTRY MIX OF SLEET...FREEZING RAIN AND SNOW WILL OCCUR. WHEN THE ARCTIC FRONT PASSES...WINDS WILL ABRUPTLY INCREASE TO 40 MPH AND A THICK SNOW WILL SUDDENLY REDUCE VISIBILITIES. THE COMBINATION OF FALLING AND BLOWING SNOW AND WIND MAY CREATE BRIEF PERIODS OF NEAR BLIZZARD CONDITIONS DURING TUESDAY."
Road and travel troubles?
I still think that the roads in the area will become dangerous overnight. On WI DOT's interactive website you can access near-realtime winter road condition information. One service is current road temperatures, and in the map (to the right) I've drawn up current road temperatures this morning. Several DOT monitoring stations are not functioning at the moment, I've labeled them as Not Available.
Some roads are near or above-freezing, while others are a bit below. Those that are in the 20s have potential to produce ice if/when the rain begins. Rain coming into contact with 25 degree roads may freeze on contact.
In addition, while air temperatures will be in the 30s today and this evening, by midnight temperatures will begin to drop below freezing. This, combined with cold roads, appears to be creating conditions that will make driving difficult.