Friday, March 01, 2013

Midweek Coastal Threat Still There

The model hype well has been running deep with hints of a large storm system developing off of the Carolina or Mid Atlantic coastline for the middle of next week. The Euro has been consistent in showing the storm stalling and intensifying off of the coastline before making a slow trek to the East.  It was been really inconsistent in track -- keep in mind it's still several days out -- either showing a track farther to the north, which brings a snowy (and rainy) scenario to the Mid Atlantic such as the scenario depicted below...

...or a track that goes through the Carolinas, which results in wind, clouds, and perhaps some coastal flooding at the Shore but a storm that takes a more southern track.  The consistency is, for now, in the storm signal on the models, but the inconsistency is in the track and detail.

This system will be fueled largely by energy that will track in from the Pacific in Canada, through Alberta, down through the Rockies, and across the Ohio Valley or Tennessee Valley before hitting the coast.  This storm is poised to intensify due to a phase between that "bowling ball" of energy that tracks through the country with a second piece of energy that pivots through the Great Lakes and gets sucked into the "larger" piece of energy as that hits the coast.  There isn't much difference in that part of the outcome -- the difference in outcome comes down to track of that bowling ball energy.

The GFS has been consistent in keeping the track to the south of us although it has started to show the stall or slow scenario once the storm system develops in the Atlantic.  However, the track of the system still remains to the south of the region for now.

In terms of details, the northern track outcome (last night's Euro) would suggest rain south and east of the city, snow to the north and west as a generality.  Some waffling in that track may nudge the rain/snow line around a bit.  A southern track means no precipitation for almost the entire region.

The bigger threat for the coast will be the steady fetch of winds off of the Atlantic, resulting in coastal flooding and perhaps beach erosion. This low is not poised to be a superbomb in intensity -- probably gets into the 990 mb range at its peak, which is hardly intense in terms of historical nor'easters -- but there's enough of a pressure gradient with high pressure to its north to bring a steady east and northeast wind off of the Atlantic.  If the more southern track takes place, those impacts would be greater for South Jersey and Delaware than for North Jersey.  If the more northern track holds, the impacts may be greater across New Jersey than in Delaware.  Unless the storm completely "whiffs" in developing, this is the bigger issue in all likelihood for you guys down there.  The snow and/or rain threat ultimately comes down to track...and that's still far from certain.