Reviewing yesterday’s snowstorm…Another on the way?

The snowstorm that southeast Michigan received yesterday into the early morning hours was quite a surprise.  Most forecasts were calling for the storm to start as all snow and then switch to a mix precipitation, giving us a threat for a significant ice storm.  Instead, most of us received all snow and a lot of it.  The unofficial totals can be seen here and on the map below.

 

Image courtesy of NWS Detroit

So why did we receive much more snow than originally forecasted?  The easy answer is the low pressure system did not go as far north as anticipated.  On the image below, the red line represents the actual path of the center of the low pressure system between 7am Sunday and 4pm Monday.  The black arrow represents the general path that model runs were forecasting in the couple days prior to the snowstorm.  It is easy to see that there is a noticeable difference in the forecasted and actual track, which made a big difference in precipitation type.

 

I am thinking that the reason why the models were so off on the systems track (until Sunday morning when they started to show signs of a more southerly track) was because of how quick it moved across the U.S.  The upper-level energy didn’t reach the west coast until Saturday morning.  Before then, the energy couldn’t be sampled in the upper air network because it was still out over the Pacific Ocean.  Once it reached the western U.S. and was sampled a time or two, then the models were able to adjust their forecast.   

With the system further south, the snow and freezing rain also shifted further south, causing most of us to see all snow.  There was a good amount of freezing rain in the counties that border Ohio with as much as an inch of ice reported in some locations.  Looking again at the snow totals map above, you can see a very tight gradient of snow totals in Monroe County.  In the southern parts of the county, there was less than 3 inches of snow but the extreme northern part of the county received 8+ inches of snow.   Overall, the heaviest snow occurred in the middle of southeast Michigan where everyone received 8-12 inches of snow.

Looking ahead, the next possible snowstorm appears to be Thursday night into Friday as a low pressure system will move from the Southern Plains into the Ohio Valley.  There is some disagreement between the models of what to expect, with some models giving us a good snowstorm while others have us only being clipped.  This system needs to be watched as it develops and moves closer to Michigan.  I will write another posting in the next couple days to give an update.