Here we go, again.
There are still a few questions about our inbound weekend winter storm. But the broad brushstrokes are becoming clearer. A significant heavy wet snow event is almost certain for a big chunk of Minnesota Saturday into Sunday.
This snow will be wetter and heavier than the past few systems. There will be wind, but with wetter snow widespread blizzard conditions are unlikely. Still, travel will be difficult Saturday into Sunday morning. Winter storm watches are up for much of Minnesota.
Let’s break it down.
The storm pulls out of the Colorado Front Range Friday. The low-pressure storm center heads through Kansas for Iowa. The storm track favors a Kansas City, Mo.-Des Moines, Iowa-Green Bay, Wis., line. That’s usually a favorable track for heavy snow in the Twin Cities, central, and southern Minnesota and northwestern Wisconsin.
Here’s the National Oceanic and Atmospheric Administration’s Global Forecast System model from 6 p.m. CST Friday until 7 a.m. CDT Sunday.
If you look closely at the model run above, you can see two potentially important things. First, the rain-snow line is near the Twin Cities at noon Saturday. Second, a very heavy burst of snow is right over the Twin Cities at 6 p.m. Saturday.
This storm looks likely to produce convective snow bursts Saturday afternoon and evening across southern Minnesota. That could mean thunder snow.
Snowfall rates may reach 2″ per hour for a few hours Saturday. Things could get crazy with lightning, thunder and snow coming down incredibly hard. If that happens, most of the accumulation could occur within just a few hours Saturday afternoon into evening.
Check out the analysis from the Twin Cities NWS in Thursday morning’s forecast discussion.
The most intense part of the storm will be where the arc of heavy isentropic snow ahead of the cyclone will intersect with the strong frontogenesis to the north of the cyclone. Snow rates here could exceed 2 inches per hour and thunder cannot be ruled out either.
The most probable track of this particularly intense snow will be 75 to 100 miles northwest of the center of the track, or roughly from southwest MN, to east-central MN and the Twin Cities, to parts of northwest and west central WI. 6-hour QPF around 0.90″ could mean 8 to 10 inches in just that time window.
If current forecast model trends hold, I can see a wide swath of 6 to 12 inches across central and southern Minnesota with this system by Sunday morning. Mixed precipitation will probably keep snowfall totals down into a general 1- to 5-inch range in southeastern Minnesota.
Here’s the latest Twin Cities National Weather Service map:
Chances for some 1-foot snowfall totals in a few towns are pretty impressive from Redwood Falls, Minn., into the Twin Cities.
If there is any bust potential with this storm, it’s in where the rain-snow line sets up.
If this jogs north even 50 miles, that could produce more rain at the beginning of the storm in the Twin Cities. If that happens, that would cut snowfall totals significantly. It’s not likely, but it’s something to watch for in Friday’s model runs.
The Canadian model is the northern outlier, but notice how it spreads rain over the entire Twin Cities around midday Saturday.
If this were to verify, that would bust snowfall totals for the Twin Cities area.
Milder through next week
Spring? Not yet.
Noticeably milder temperatures arrive Friday and hang around through next week. Another low-pressure system arrives next Tuesday and Wednesday. It looks mild enough next week that next week’s system looks more likely to be mixed with rain.