NOAA SREF model ensembles show heaviest snow bands (9″+) in southeast Minnesota, Iowa and Wisconsin.
Blizzard warnings are in effect Tuesday for much of southern Minnesota and northern Iowa, as a powerful winter storm takes aim at the Upper Midwest. The combination of snowfall totals of 6″ to over 12″ along with high winds gusting to over 45 mph and falling temperatures will create dangerous travel conditions Tuesday into Wednesday.
Winter storm warnings are in effect elsewhere, including the Twin Cities.
Look for snow to begin Tuesday morning in southern Minnesota, and to spread into the metro by lunchtime. The heaviest snow should fall Tuesday night. The weather will be worst for the Tuesday PM and Wednesday AM commute times.
The major winter storm is coming ashore near Los Angeles late Monday afternoon.
What we know for sure:
-This is a large storm in terms of geographic coverage. It will affect travel in several Midwestern states. Watches or warnings are posted for as many as 22 states for this storm system.
-It appears the heaviest band of snow will set up from near Des Moines through La Crosse, Madison and Green Bay. These areas could see 6″ to 12″+ by Wednesday evening. There could be some 18″ totals with this system if convective snowbursts (thundersnow) develop.
-High winds are likely to gust over 45 mph Tuesday night and Wednesday. This will cause considerable blowing snow and near zero visibilities in open areas.
-Very cold air will follow the storm. Temperatures will fall into the single didgits above zero Wednesday, and wind chills will plummet well below zero.
-The biggest uncertainty with this storm may be how much snow falls in the Twin Cities metro. The Twin Cities will be on a razors edge on the northwest side of the storm.
There are several factors working for and against heavy (6″+) snow totals for the metro.
-Various snowfall forecast techniques such as the Cobb Method yield 6″ to 8″ of snow for the metro.
Cobb Technique meteogram indicating 8″ snowfall for the Twin Cities.
-The track of the surface low is slightly farther to the southeast (over Chicago) than the ideal track for heavy snow in the metro. Surface lows that track between Madison and La Crosse usually produce the heaviest snow bands over the metro. If the low tracks any further south, that could limit snow totals in the metro, especially on the northwest side.
–Model ensembles (SREF) laetst runs favor amounts slightly under 6″ for the metro.
My best estimate for snowfall totals by late Wednesday for the metro is between 3″ and 6″ with the heaviest amounts in the southeast metro. I am still watching the possibility that the storm tracks further south, and we end up with less snow in the metro.
Fortunately, we still have two more model runs (tonight and early Tuesday) before the snow begins. I will tweak snow amounts as new data rolls in.
The bottom line is everybody should expect some snow, high winds and very cold air over the next 48 hours. If you are planning travel anywhere, especially to the south or east, be ready for severe winter storm conditions.