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Possible snowstorm from the Mid-Atlantic to coastal New England Tuesday

Surface weather map forecast for the morning of Jan. 21, 2014.  Heavy snow is expected to develop west of Washington, DC by this time.
Surface weather map forecast for the morning of Jan. 21, 2014. Heavy snow is expected to develop west of Washington, DC by this time.
NOAA/NWS

As the polar vortex reasserts itself over eastern Canada, one of the many “clippers” (see article from Jan. 19, 2014) rotating around it appears ready to spawn an East Coast snowstorm. If the computer and human forecasts verify, some 3 to 5 inches of snow (or more) could fall across the Mid-Atlantic Tuesday (Jan. 21, 2014) before the storm heads for southern and southeastern coastal New England. Offshore, the storm should generate strong winds and high seas later on Tuesday and into Wednesday. Winds should increase to gale force (39 miles per hour or greater) and seas build to 19 feet.

If the storm moves the classical “50 miles to the left or right” of the expected track, then, anticipated snowfall amounts could shift, as well

As the snow falls, so, too, will the temperature. Following a Martin Luther King Day high of near 50 degrees in Washington, DC, temperatures will tumble overnight into the upper 20’s. After holding steady early on Tuesday, look for temperatures to fall into the teens by evening. On Wednesday, the forecast high-low range (7 to 18) will be even lower than the range of 6 to 21 back on Jan. 7, 2014. On that day, the temperature averaged 22 degrees colder than seasonal average. The forecast departure from average for Wed, Jan. 22, 2014 would be 23 degrees colder!

Thanks to the expected snow cover and the position of the polar vortex, cold weather will linger across the Northeast quadrant of the Nation throughout the week; temperatures will remain well below average.

As noted yesterday, this cold weather pattern has about a week to go before it breaks down and allows weather systems to progress across the Nation. This would allow the temperatures nationwide to return to near average values before the next arctic assault arrives near the end of the month. That arctic blast could bring icy weather to the Tennessee Valley and possibly even northern Alabama and Georgia.

While regions to the east of the Rockies are locked in a cold pattern, places to the west of the Rockies continue in the throes of a very warm weather pattern and an associated, prolonged drought. An upper level ridge (shaped like an upside down “U,” continues to steer storms to the north of the region. It also leads to strong subsidence events with associated well-above temperatures and Santa Ana winds (much like what occurred in northern California in late November 2013).

There is no hint that any substantive precipitation will fall in California for the remainder of the month. There should be at least significant storm that will affect the Pacific Northwest in the next ten days.

© 2014 H. Michael Mogil