Dangerous weather Wednesday: Minnesota ripe for first-ever December tornadoes

Fueled by a strong storm and record December warmth, Minnesota faces an unprecedented late-season, dangerous severe weather event.

The storm also brings areas of fog, rain, snow and exceptionally high winds, before sending temperatures crashing Thursday.

Dangerous weather Wednesday

By Wednesday morning, Minnesota was already in the warm sector of an intense storm that will track directly across the state during the day, potentially bringing record low pressure for December.

Because of the warm air and moisture advection, the day started off not only exceptionally mild, with temperatures in the 30s and 40s, but also with widespread dense fog and drizzle.

The fog will lift as winds increase during the day, while temperatures continue to rise into the 40s for most of the state. In southern Minnesota, temperatures could climb even after sunset, with a few 60s possible in the evening before the cold front of the storm moves through.

Those temperatures are likely to set widespread record highs, including for the Twin Cities.

The storm carries a lot of moisture, and record dew points (moisture in the atmosphere) for Dec. 15 could also be set.

The low pressure of the storm is forecast to move quickly across Minnesota during the evening hours. The intense nature of this storm, fueled by record warmth and ample moisture will provide the dynamics needed for a significant severe weather event.

Severe weather is possible from southwestern Minnesota late Wednesday afternoon through southeastern Minnesota until about 9 or 10 p.m. Wednesday evening.

The storms will be incredibly fast-moving at about 60 to 70 mph, producing damaging wind gusts that could top 80 mph. While wind is the primary threat, tornadoes are also likely, particularly in southeastern Minnesota.

This makes Wednesday’s weather event not just record-setting (possible record temperatures, dew points, late-season severe weather), but unprecedented with a tornado risk this late in the season.

The current record for latest tornado in Minnesota is on Nov. 16. Among Minnesota’s neighboring states, only Iowa has recorded a December tornado.

The storm also brings significant rainfall for December, with portions of southern and central Minnesota seeing one-half to 1 inch of rain.

In northern Minnesota, where the cold front goes through earlier (moving from northwest to southeast), up to 5 inches of snow is possible.

The cold front also brings high winds separate from the thunderstorm winds. In northern Minnesota, gusts up to 50 mph could produce near-blizzard conditions with blowing snow.

In southeastern Minnesota, where the front passes through last, late Wednesday, the gusts with the front will be the highest, likely over 60 mph at times. The high winds have the entire state under some form of advisory or warning.

The winter weather advisory northwest (purple) is due to the high winds plus snow reducing visibility. The wind advisory north (light beige) and high wind warning south (dark beige), are for winds that could top 50 and 60 mph respectively.

This exceptional storm will also be quick to drop temperatures. In the Twin Cities, for example, temperatures could drop about 30 degrees in 8 hours, from near 60 Wednesday evening to the 20s Thursday morning.

This means many of the wet areas around the state from the melting and the rain could freeze suddenly, making for slick conditions Thursday.

Precipitation ends by early Thursday, winds diminish during the day, and more sunshine returns by the afternoon. The chillier temperatures from the storm linger through the end of the week though, with highs only in the teens and low 20s.

Programming note

You can hear my live weather updates on Minnesota Public Radio at 7:49 a.m. Monday through Friday morning.