Winter storm warning through 9 p.m. Tuesday; cold winds howl Wednesday

Updated 12:25 p.m.

Tuesday’s heaviest snow bands will be over the Twin Cities from about 2 p.m. to 3 p.m. Snow wraps up between 6 p.m. and 8 p.m. in the Twin Cities but will run through the night north and east.

Expect an additional 2 to 3 inches through Tuesday afternoon on top of the 3 to 4 inches many have seen already from Mankato through the Twin Cities into western Wisconsin.

A snowy Tuesday with poor travel conditions

The heaviest snow will fall through the midafternoon across south-central into east-central Minnesota through the Twin Cities and western Wisconsin.

The most intense snow bands are moving through early this afternoon as the best vertical velocities (upward motion or lift) occur over the region.

We may not quite see the highest possible snowfall ratios since the best lift will happen below what meteorologists call the “dendritic growth layer.” This is the layer where optimal, large snowflakes develop (think of the kind with many arms).

Forecast profiles of the atmosphere show the best lift (circled) below the this layer (outlined in blue).

Still, the National Oceanic and Atmospheric Administration’s Storm Prediction Center does anticipate some places could see up to 1 inch per hour rates into midafternoon in east-central Minnesota and western Wisconsin (outlined in purple below).

As of noon, the Twin Cities has seen about 4 inches of snow with another 2 to 4 inches possible this afternoon.

There will be a large area of 3 to 6 inches in total across southern Minnesota with a narrower band of 6 to 8 inches that could fall within that, including through the Twin Cities.

Here’s the official National Weather Service forecast for the overall storm total:

There will, however, be quite a lot of variation due to differences in moisture content and the range of ratios of snow to water (ranging from 10:1 to 15:1 in some spots). Here are the two minimum and maximum modeled possibilities:

The snow should end by 8 p.m. in the Twin Cities and taper off through the night in Wisconsin.

Temperatures will drop from around freezing in the morning into the 20s late in the day and winds will increase from just 5-10 mph to 15-20 mph by evening from the northwest.

Windy, colder Wednesday

Winds will howl Wednesday as colder air settles in across Minnesota. Sustained wind speeds of 15-25 mph and gusts of 30-40 mph will whip around snow in open areas.

Wind chills will be subzero west and just above zero in eastern Minnesota.

We do warm up already with highs near 40 for southern Minnesota again by Friday afternoon.