The 3rd in a series of 3 Northeast U.S. snow storms is upon us as all of New England is beneath a winter storm warning with blizzard warnings issued for east/southeast Massachusetts. 1-2 feet of snow is likely for much of the region with a storm that begins tonight and roars through most of Tuesday.
From a climate perspective, the series of Northeast snowstorms – the first of which caused widespread damage from coastal flooding and hurricane force wind is the end result of a tropical to polar interaction nearly one month ago. Just-after mid-February a massive area of long-duration convection in the equatorial West/Central Pacific Ocean shifted east and weakened. During the weakening process heat release to the upper atmosphere pole ward was so strong warming reached the stratosphere and arced into the polar region at a very high altitude.
The warming stratosphere caused arctic air to form at ground level this time in Central Russia. The coldest temperatures of northern hemisphere winter were observed and along the south and east periphery of this air mass snowfall became persistent. Snow cover invited the arctic air mass westward to U.K. and southward to Italy. A negative North Atlantic oscillation slowly evolved during this pattern.
The -NAO pattern became intact in early March. Initially, the blocking pattern forced vigorous Northeast storms but without arctic air. The intensity of the storms caused locally cold air to develop causing heavy snows for the Northeast. However, gradually the lengthy duration of -NAO has produced sprawling cold across eastern Canada and that air mass flows south into the next storm. The lack of warm air ahead of this storm means a slightly farther east track…well east of Nantucket but slowing and producing a central pressure of about 970 MB similar to the early March storm.
The eastward displacement of this storm forces a cold north wind (instead of milder marine influence) into the back side of the storm system therefore this time it’s all snow, most near the coastline.
In the winter storm warning area at least 6 in. of snow is likely which includes all of New England except Vermont. 1-2 feet of snow is likely for central and eastern New England including the coastal areas where blizzard conditions are likely due to snowfall intensity and strong wind.
The storm is slow to let-up likely waiting until Wednesday. The -NAO pattern is forecast to fade after this storm which should be the last of the intense snow events of early-to-mid-March.
Latest Northeast snowfall forecast…