One more cold day; mild on the winter ‘misery’ index

This cold spell will be short.

Our official low temperature hasn't dropped below zero at Minneapolis-St. Paul International Airport since Jan. 13.

We'll be flirting with zero early Thursday morning, and much of northern Minnesota will see teens below zero.

The National Weather Service has a wind chill advisory in effect until 9 a.m. Thursday morning for northwestern Minnesota:

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NWS Grand Forks, ND

Wind chills of minus 20 to minus 35 degrees are possible in the advisory area.

Afternoon highs on Thursday will be close to 20 in southern Minnesota, with a lot of teens elsewhere. Far northern Minnesota could see single digit highs.

Our average high temp is 27 degrees this time of year in the Twin Cities.

A very warm front

An approaching warm front will generate some periods of snow over northern Minnesota Thursday night.

The National Oceanic and Atmospheric Administration’s North American Mesoscale forecast model shows the projected snowfall pattern over northern Minnesota:

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NOAA NAM model simulated radar Thursday evening through Thursday night, via tropicaltidbits

The color chart on the lower right of the loop refers to the strength of the radar signal returning to the radar, not inches of snow!

How warm is this warm front?

Southern and central Minnesota will see highs in the 40s on Friday, and a few spots in the southwest could touch 50 degrees. Northern Minnesota will top out in the 30s.

Saturday's high temps will also be well above normal:

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Mild temps stay with us into next week.

NOAA's Global Forecast System model shows mild temps continue into the third week of February in the Twin Cities:

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NOAA GFS model temps, via MeteoStar

Our average temperature for the month of February is likely to finish warmer than normal in the Twin Cities.

Winter Misery Index

It's time for an update on our Twin Cities Winter Misery Index (WMI), courtesy of the Minnesota State Climatology Office.

The definition of the WMI is:

The Winter Misery Index (WMI) is an attempt to weigh the relative severity of winter when compared with winters of the past. The WMI assigns single points for daily counts of maximum temperatures 10 degrees F or colder, and daily minimums of 0 degrees F or colder.

If the minimum temperature drops to -20 degrees or colder greater, eight points are attributed to that day. Snowfall totals of one inch or greater in a day receive one point. Four-inch snowfalls generate four points for the day, an eight-inch snowfall receives a whopping 16 points. The duration of a winter is quantified using the number of days the snow depth is 12 inches or greater.

We currently have a WMI of 48 points:

As of February 8, 2017 the WMI for the 2016-17 winter is at 48 points: 23 points for cold, 25 points for snow. This is enough for this winter to be in the "mild" category. Seven more points are needed for this winter to be categorized as "moderate."

The WMI for the winter of 2015-16 finished with 47 points, enough for 2014-15 to be categorized as a "mild" winter. The WMI points for the 2015-2016 winter were 18 for cold and 29 snow: 47 points.

You'll remember the "polar vortex" winter of 2013-2014:

The WMI for the winter of 2013-14 in Twin Cities was 207 points, or in the high end of the "severe winter" category.  This was the 9th most severe winter on record based on WMI points. The lowest WMI score was the winter of 2011-2012 with 16 points. The most severe winter is 1916-1917 with 305 WMI points.

Of course, the WMI would be scored differently by snow lovers, who wouldn't add points to the WMI when it snows!

If you're curious about the ups and downs of the WMI through the years, take a look at this graph:

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MN State Climatology Office

I remember the non-winter of 2011-12 very well!