By the time you read this, a significant snow and ice event will have moved through the Northeast, signaling the start of the pattern change that I alluded to in my last installment. The stratospheric warming event that I discussed in my last installment has matured and now it is time for us to reap the benefits.  The polar vortex has been distorted by increasing pressure from the warming above and the cold air contained in the vortex has started to spread out to the mid-latitudes in several parts of the globe.

Colder air has already built up over much of Canada, as you can see from this map of surface temp anomalies from this morning.

Although the core of the colder air is located over the western half of the continent, that cold air will be progressing eastward as we head toward March.  In addition, the cold over eastern Canada is poised to be pulled south by the circulation around any sort of low-pressure center that moves through the Northeast.  There are two other things I want you to notice about this map.  First, the zone that separates the colder than normal from the milder/warmer than normal air masses stretches from Oklahoma to central New England.  This “baroclinic zone” is the likely storm track in the near term as low pressure systems feed off the thermal contrast available for energy to support the storm.  So, there will still be rain/snow lines to be concerned with, but that zone will be sinking southward as we head into March.  Lastly, notice the current warm anomalies over Greenland…those suggest the presence of an upper level ridge overhead and indeed, if we look at this snapshot of jet stream features for the same time we see an upper ridge poking its way into Greenland from the East.

If that ridge strengthens and expands westward over the next couple of weeks, an active storm track will develop underneath it…right through the eastern United States.  If we take a look at a jet stream forecast for the end of the first weekend in March, we will see that there is model support for this idea.

The ridge will extend west into northeast Canada with a broad trough covering much of the Lower 48.  Energy will come out of the piece of the trough in the Pac Northwest, traverse the country from west to east and feed off the thermal contrast that will still exist from the Ohio Valley to the east coast…that thermal ribbon will be further south, though, and that will mean opportunities for late season snow in the central Appalachians.

Here is a very interesting frame that shows the surface pressure tendencies for the 30 day period following the maturation of a stratwarm event…

The orange area shows high pressure anomalies over Greenland and the polar regions and the blue shows a tendency for low pressure areas along the eastern seaboard…can you say “late season Nor’easter”?  A jet stream set up like the ones shown for early March is one that is very favorable for eastern snowstorms.  Furthermore, with a strong ridge over Greenland and Canada effectively blocking the progression of systems around the northern hemisphere, the pattern is likely to remain in place for an extended period…perhaps much of next month.  Last…and certainly not least, here is a forecast for bountiful snowfall through the first week in April…

Based on a multitude of factors, some of which I have laid out in this piece, I think that the amounts you see are feasible, if not likely.  Better late than never, eh?