Sunday snow bust, major thaw this week

Anatomy of a snowfall bust

I think I got all the egg off my face this morning.

Sunday's snow caused the expected impacts as it produced dangerously icy roads and numerous accidents and unfortunately one fatality, but snowfall totals were a bust for the Twin Cities. Even as the storm delivered on projected snowfall for other parts of Minnesota and parts of South Dakota and Iowa. Many forecasts from Friday (including mine) were too high for eventual snowfall under an inch in the metro. The Twin Cities NWS had the cold right, but projected metro snowfall totals up to 6" with this graphic Friday morning.

What happened to produce less snow than expected? Here's some candid Monday morning (literally) quarterbacking and perspective on Sunday's snow metro bust.

• Models often over-predict snowfall, that's a working assumption in the weather biz.

• Friday's NOAA's Short Range Ensemble Forecasts (SREF) 26 models produced an average forecast snowfall range of over 5" for the metro Sunday.

• Even the usually trusty European Model over-projected Sunday's snowfall.

• My early snowfall forecast Friday more than 36 hours before the event took the low end of the model spectrum forecasting a 2" to 5" range in the metro. Even while taking the low end of model output, I still wrote this about some doubts I had regarding metro bust potential on Friday in this space. I’m not completely sold on the (above/NWS) notion of 6″ snowfall potential in the metro just yet, but this system will have to be watched closely to see just where the heaviest snow bands set up Sunday morning. I still think the heaviest bands could set up just south and west of MSP.

• The system produced the expected snowfall totals up to 9" in South Dakota, but was weakening as it approached the Twin Cities. Forecast models often have a difficult time with weakening systems. That's one reason the models over projected snowfall for the metro.

• Even though metro snowfall totals came in at 1" in Chanhassen and 0.7" at MSP Airport, the impacts of icy roads and numerous accidents were there. It's a good reminder once again that pavement temperatures during snowfall, and system impacts are more important than inches in snowfall events. Last night's tweet from the Twin Cities NWS reminds us why as little as half an inch of snow can turn roads into skating rinks.

Next Clipper overnight and Tuesday morning

The next fickle Clipper rides east into Minnesota late tonight into tomorrow morning with another shot of light snow. Again it may be enough to produce impacts and mess with rush hour Tuesday morning. Impacts. Plan accordingly.

Milder days ahead

Our warm up this week is gradual at first, then kicks into high gear later this week. Here's a look at the major thaw heading this way later this week according to the Euro model.

The average high by this weekend reaches the 30 degree mark in the Twin Cities. The gush of our inbound Pacific air mass will be a good +10 to +20 degrees vs. average.

Wilting snow later this week

Daytime highs in the 40s, and 3-4 consecutive nights at or above freezing will do a number on the 2" of Twin Cities' snow cover by Sunday. Keep in mind there's still plenty of snow to play in up north, with 20" near Ely and 25" around the Wolf Ridge ELC near Finland. There are also pockets of heavy snow depth near Rochester and in southwest Minnesota.

Here's this morning's snow depth map from NOAA's National Operational Hydrologic Remote Sensing Center.

Ski Pipestone?

Stay tuned as we tweak the magnitude of the thaw event later this week.