Monday, November 5, 2012

November 5, 2012: Moderate Nor'easter Weather Impact for Baltimore

November 6, 2012, 4 PM:  Baltimore Nor'easter Impacts
Scenario and Timeframe
Our region is expected to pass through the back edge of a strong Nor'easter.
The various models portray the development of a Nor’easter off Cape Hatteras on Wednesday.   The storm will track N-NE and rapidly intensify off the NJ coast.   The storm may briefly stall off the NJ coast on Thursday, before moving NE away from the coast Thursday night.
The biggest impacts from this storm will be along the coastline from the Delmarva northward along NJ, NY and New England.
For Baltimore, the moderate weather impacts will occur during a 12-18 hr period from Wednesday night into Thursday morning.
Weather impacts will generally diminish moving inland from the coast (except at the higher elevations i.e. Catoctins, Appalachians – where winds will be higher and probability of snow is greater).
The following sequence of surface weather charts shows the general progression and intensification of the storm, at various times:
7 AM Wednesday. Storm develops, deepens, moves slowly north. NWS.

7 PM Wednesday.  Storm deepens, moving slowly north.  NWS.
7 AM Thursday. Storm reaches lowest central pressure.  NWS

7 PM Thursday.  Storm weakens, moves away toward northeast.  NWS

Another way to look at the evolution of the storm is to plot the likely storm center and intensity as a function of time:

Model Forecast Nor'easter Track and Intensity.  NWS

Up to an inch of precipitation will fall, with higher amounts along the coast, lesser amounts inland.  The rain may mix with snow Wednesday night.   Accumulation will be light, if any.   
This chart shows the liquid equivalent precipitation amounts:
Total liquid precipitation.  NOAA
This chart shows the probability of > 4” snow.  Note that there is only a slight probability of heavy snow well to our north, in the Poconos of PA.  
Probability of > 4" (Heavy) snowfall. NOAA
The most significant sustained and gusty winds will occur along the coast, from the Delmarva to Cape Cod.
Winds may gust 40-50+ mph along the Delmarva coast. 
Inland, including Baltimore:  Gusts 30-40 mph possible Wed night into Thursday morning.

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