Saturday, March 02, 2013

Midweek Storm Impacts Probably Greater To South

Looking at the midday guidance we see the continued track of the midweek storm to the south of Philadelphia, with the Euro still leading and nudging the system a bit farther north than the GFS.  That said, the track of the storm was virtually unchanged on the Euro.  The GFS, with the exception of the late afternoon run, has consistently been a bit farther south and has kept precipitation out of the immediate Philadelphia metro.  The late afternoon run did not...but it is an aberration, not a trend, at this point.

With the Euro output we would be right on the fringe of precipitation, which in a March storm is not the best setup for snowfall.  Given there's also going to be dry air funneling in from the northeast in the lower and mid levels, wouldn't surprise me if precipitation has a bit of a hard time getting this far north in such a track.

That said, wherever the low goes, areas just to the north are in line for significant snowfall.  The two maps below are the GFS snowfall output projection followed by the Euro.

Both show significant snowfall possible across Virginia back into the Ohio Valley, as well as the possibility of significant snowfall into Southwestern Pennsylvania if the Euro's more northern track were right.  Snow will fall in the areas where heavier precipitation is expected...the question comes down to track and detail at this point in terms of the wintry end of this storm.

In terms of coastal flooding and beach erosion, the storm has trended slightly weaker in modeling.  We're not talking about a mega 980 mb or lower storm.  However, its movement will slow as it hits the coast and it will intensify somewhat, probably to just under 1000 mb -- somewhere in the mid to high 990's.  The pressure gradient between the low and the high over New England will provide strong winds across South Jersey and Delaware, with some beach erosion possible at times of high tide on Wednesday and early Thursday.  Minor coastal flooding is certainly possible down there as well.  If the storm ends up taking a track that's a bit farther north, the outcome and endgame on results will nudge north accordingly.  I don't foresee a massive shift to take heavy snowfall across Southeast Pennsylvania and Central Jersey, however, but it's possible some of this storm does produce snowfall at the most intense intervals for Delaware and the Delmarva.  The detail on that is still very much to be determined.