Monday snow mostly on track, 6″ to 14″ metro range

I noticed a lot more gray hair in the Weather Lab mirror tonight.

After three days of basically rock solid forecast model runs suggesting the same storm track and heavy snowfall distribution, some of Sunday evening's model runs showed a distinct northward jog in the expected storm track. As if we needed another reminder on why forecasting snowfall for winter storms is among the most difficult forecast meteorologists have to make?

Here are some updated headlines as we look toward the Monday morning commute.

• Winter Storm Warnings remain in effect until noon Tuesday for the metro and much of Minnesota/Wisconsin.

• Expect snow and deteriorating road conditions for Monday morning rush hour.

• Monday afternoon and Tuesday morning rush hours should be the most snow covered & challenging.

• Sunday evening's model runs showed a slight shift north in storm track.

• The heaviest snow bands of 8 to 16 inches or more likely will shift slightly north, Morris-Willmar-St. Cloud-Hinckley zone.

• I am trimming forecast Twin Cities metro area snow totals slightly, a metro range of between 6 and 14 inches now seems most likely. 

• Heaviest metro snowfall totals will likely favor the north and northeast metro.

• Peak metro snowfall rates should favor Monday afternoon and night.

• Snowfall totals will drop of as you move south of the metro.

• A band of freezing rain and ice will coat roads and create icy travel in southern Minnesota south of the metro.

Bottom Line: A significant high impact winter storm event is still imminent Monday through Tuesday morning.

NAM Model head fake?

The oz NAM model and RAP (rapid refresh model) showed a northward jog of about 50 miles in storm track and location of the heavy snow axis. Considering the Twin Cities metro is about 30 miles long, a 50 mile shift can make a world of difference in eventual snowfall totals.

Sunday evening's NAM model shifted the heaviest snow band north of the metro, and greatly reduces the previously consistent model snowfall output that showed totals between 8 and 16 inches for the metro.

If the shift is accurate, that heaviest snow band of between 8" and 16"+ will lay out north of the Twin Cities, along and either side of a Morris-St. Cloud-Hinckley-Duluth line.

On the other hand, the National Oceanic and Atmospheric Administration's Global Forecast System model showed just a slight shift north, keeping heavy snow totals into the metro, with some lighter totals in the south metro.

I am sticking with the Global Forecast System trends at this point and trimming snow totals slightly for the metro, and shifting the heaviest bands of 8 to 16 inches or morejust north of the Twin Cities.

It appears we're  still going to get a high impact snow event in the metro Monday into Tuesday morning that will impact roads and travel significantly.

Plan accordingly and stay safe!