Blizzard to Cripple NE US Friday and Saturday

HEADLINE:

BLIZZARD CONDITIONS LIKELY THROUGHOUT THE I-95 CORRIDOR, NEWARK, NJ AND POINTS NORTHEAST

SYNOPSIS:
A rapid-deepening nor’easter will form in the warm waters of the Gulf Stream near the Delmarva Peninsula late Thursday Night in association with a pair of vigorous low pressure systems, one tracking across the Southeastern US and another diving in from Central Canada.  These two systems will merge late Thursday Night and coalesce into a crippling winter storm for the entire Northeast, with the heaviest snows beginning late in the day on Friday and ending Saturday evening.  The storm is likely to produce in excess of a foot of snow over a large portion of Southern New England and the tri-state area, as well as damaging coastal flooding, storm surge and winds that could gust to hurricane force.  This combination of damaging winds, beach-battering waves and heavy snows could make travel difficult or impossible through the weekend and imperil already-stressed power grid systems still suffering from lingering disrepair in the aftermath of Superstorm Sandy.
BACKGROUND:
As noted above, the threat of blizzard conditions is expected to develop through a complex interaction of two small, but vigorous upper-atmospheric troughs.  This process of phasing will be aided by a strong blocking ridge near Hudson’s Bay in Canada, which will help to hold ample low level cold air in place over the NE US.  This ridge of high pressure will clash with a rapidly deepening nor’easter to produce a large pressure gradient along the New England coast, as well as conditions favorable for intense banding of snow NW of the center of low pressure.  Due to the complex nature of the set-up for this storm, the forecast process has remained highly uncertain throughout the week, but various weather prediction models have begun to forge a general agreement on the likely track and intensity of the storm, with differences in the forecast generally limited to small wobbles in that track, the exact temperature profile in the atmosphere near the center of circulation, and the structure and placement of snowfall banding.  With an improving confidence in the ensemble of weather models in the forecast track of the storm, I am issuing a preliminary threat assessment including a snowfall, surge and wind forecast, and stating that my confidence in this preliminary forecast is above average.
SNOWFALL:
Six inch line:
Trenton, NJ
Wilkes Barre, PA
Binghamton, NY
Buffalo, NY on the SW side

Caribou, ME on the N side

and excluding the far East end of Cape Cod, Montawk, NY and Sandy Hook NJ on the SE side

Twelve inch line:
Newark, NJ
Newburgh, NY
Glens Falls, NY
VT/NY/Canada triple point on the west side

and

Sandwich, MA
Westerley, RI
Southampton, NY on the SE side
Twenty-four inch line:
Bridgewater, MA
Providence, RI
Just East of Hartford, CT
Springfield MA
Concord, NH including Boston, MA and the threat of the inclusion of central Long Island, NY, especially along the North Shore and from Huntington to Miller Place
Max snowfall: up to 36″ possible and the most likely impact would be felt near the Boston metro area.
WIND:
Blizzard conditions (visibility less than 1/4 mile for three consecutive hours, winds in excess of 30 mph sustained, and heavy snow falling) are likely throughout the 12+ inch region highlighted above excluding the far interior counties, which are least likely to feel the full force of the wind.  Near the Atlantic Seaboard, sustained tropical storm force winds in excess of 50 mph are possible, especially along exposed barrier islands and beaches (Block Island, RI, Nantucket and Martha’s Vinyard, Fire Island, NY, the twin forks at the east end of Long Island and all of Cape Cod and the entirety of Boston Harbor, NY Bight and Coastal N NJ).  Away from the beaches, lesser but still impressive 35-45 mph sustained winds may be felt for a time, and winds throughout the coastal zones could gust as high as hurricane force.
SURGE & COASTAL FLOODING:
The worst of the winds will thankfully be limited to a 12-18 hour period, and the storm itself is likely to be relatively intense, but also small in size.  This will limit the fetch of winds aiming seawater at the East Coast and keep surges to manageable levels compared with Superstorm Sandy.  However, seas could rise a meter above tidal norms in surge-favoring locations like the Battery in NYC and Cape Cod – enough to cause some coastal flooding in low-lying towns and cities.
IMPACTS:
My primary concerns, apart from the obvious difficulties posed by a major snow event for travel, involve the ongoing efforts to repair and secure coastal power grids in the wake of Sandy this fall.  A cursory glance through much of Long Island and Southern New England reveals a patchwork of temporary repairs designed to restore power services as quickly as possible after the devastating damage dealt to the power grids this October.  Far from being in ordinary working condition, many of Long Island’s power poles, transformers, and power stations are leaning, broken and awkwardly reattached, or under trees severely weakened by multiple recent high wind events.  The combination of heavy snow and tropical storm force winds threatening this region are likely to cause major power disruptions in the heart of winter and temperatures are expected to remain cold for two or three days following the storm.  Not only that, but efforts to restore power may be hampered by snow-covered roads and travel restrictions to aid snow-removal.  I would urge coastal residents in the affected areas to prepare other methods of generating heat (firewood, small generators, gas stoves) and stock up on supplies before the weather deteriorates.
Based on the population exposed to threat of heavy snows, this will likely be a NESIS 1 or 2 storm, but it may cause damage and financial losses in the hundreds of millions, so stay tuned.
Further updates on this storm as things further develop.
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