Complex storm this week leaves unanswered questions

Forecast models all over the place on eventual snowfall totals

Forecast weather conditions for 5 a.m. Wednesday.
Forecast weather conditions for 5 a.m. Wednesday.

Minnesota’s next inbound storm system this week looks messy on the ground, and on the forecast models.

Meteorologists love clarity and consensus in forecast models. This week, we have little of either.

There’s a lot of ambiguity in precipitation types with our next inbound storm. So it’s often best to take an approach with these systems that centers around what we likely know with higher confidence, and identify what storm elements still show lower confidence.

Higher-confidence storm elements

The system

Another fairly strong low-pressure storm tracks through Iowa this week. Minnesota rides the northern zone of the storm, which is generally the highest precipitation area. NOAA’s GFS model shows the storm track through Iowa, spreading a mix of rain, ice and snow into Minnesota from Tuesday afternoon into Thursday morning.

noaa gfs model 2
NOAA GFS model between 7 p.m. Tuesday and 1 a.m. Thursday.
NOAA via tropical tidbits

Precipitation totals

Note the slow-moving forward speed of this system. That should bring multiple waves of precipitation that will wring out more than an inch of (liquid) moisture from the Twin Cities south and east.

Most forecast model solutions crank out around an inch of moisture around the Twin Cities and in most of southeast Minnesota. NOAA’s GFS leans higher, with locally 2 inches of moisture for southeast Minnesota.

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NOAA GFS precipitation output
NOAA GFS precipitation output.
NOAA via pivotal weather

Lower-confidence storm elements

Ice zone across central Minnesota

Forecast models are mixed on temperature profiles and precipitation timing zones for different parts of Minnesota with this system. Overall it seems like the freezing zone will set up across central Minnesota Tuesday night and Wednesday. This could produce some ice accumulations on either side of an Alexandria, St. Cloud, Brainerd, Mille Lacs, Hinckley zone.

NOAA’s GFS ice accumulations may be overdone here. But the notion of icy accumulations north of the Twin Cities seems reasonable.

NOAA GFS ice accumulations
NOAA GFS ice accumulations.
NOAA via pivotal weather

General it looks warm enough for mostly rain through most of Wednesday in the Twin Cities and southern Minnesota, and cold enough for mostly snow across most of northern Minnesota.

Forecast weather conditions for 5 am Wednesday
Forecast weather conditions for 5 am Wednesday.

Snowfall totals and locations

A winter storm watch is posted for northeast Minnesota. Most forecast models agree on several inches of wet snow across northern Minnesota.

Snowfall projection for northeast Minnesota
Snowfall projection for northeast Minnesota.
Duluth National Weather Service

Here’s the current snowfall projection for Minnesota from the Twin Cities NWS.

Snowfall projection for Minnesota
Snowfall projection for Minnesota.
Twin Cities National Weather Service

The American GFS and Canadian model suggest a second pulse of moisture could surge northeast Wednesday night and Thursday across southeast Minnesota, where temperatures could be cold enough for all snow. If this happens, a narrow band of heavy wet snow could set up just south and east of the greater Twin Cities.

NOAA’s GFS may be out to lunch, but it cranks out a potentially heavy band of snow Wednesday night and Thursday from along Interstate 35 south of the Twin Cities through southeast Minnesota toward Red Wing and Eau Claire, Wis.

So in my view, there is still higher uncertainty about potential snowfall totals for the Twin Cities and southeast Minnesota.

The most likely scenario at this point is for mostly rain for the greater Twin Cities and southeast Minnesota. maybe a couple more slushy inches around the twin Cities by Thursday morning.

But there is also a potential for a second wave of snow that could lay down a band of more significant snowfall from near the Twin Cities through southeast Minnesota by Thursday morning.

Expect warning and advisory areas to shift as they are updated in the next 48 hours across Minnesota.

Stay tuned.