Severe Weather Threat For The East Coast This Weekend?

Mike Masco
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A forecasting headache is ahead as there appears to be multiple solutions on the table in regards to a storms system that will moving into the eastern third of the nation.  The storm in question is still out over the northern Pacific waters at this time which means the data gathering is limited to a few buoys and simulations.

Short term Forecast.

The Storm over the next 48 hours will come ashore over Alaska and drop down the backside of a ridge west central Canada.  Intensity will play a critical role in how deep the trough gets coming into the Pacific NW.  At the same time a strong Jet Streak will come ashore over OR/WA coastline digging SE on the front side of the Rockies. If the NAM is handling this solution correctly, this would be enough to carve a long wave trough over the center portion of the county.

Agreement: EURO , CMC, GFS




Beyond 72 Hours we come into multiple solutions.  Each solution plays one extreme against the other with rain total potentials between .25 - 2.75" ! THAT my friends is not a compromise ! !

THE CANADIAN (EXTREME SOLUTION)
I call the Canadian 12z model idea the Extreme solution due to the intensity it sees the weekend storm becoming.  I also call it extreme because of the severe weather potential it is showing from GA - NY

The CMC model has a developing low pressure system over the TN valley by Saturday morning with strong WAA (Warm Air Advection) advecting all the way to VT.  The CMC deepens the storm much quicker than all the models creating a full negative tilted jet stream by Saturday evening.  It is at this time dangerous thunderstorms will develop inside the warm sector for GA , NC, SC, VA, MD and beyond going into Sunday.  The Windshear field will expand creating enough spin for potential tornadoes.




THE GFS (COASTAL SOLUTION) 2nd Worst solution

THE GFS follows the CMC's lead with a full phase between the pacific jetstream and southern jetstream.  Warm air will advect northbound however, the region of instability will be confined from eastern VA, NC, SC, FL as the trough will swing further east becoming negative tilted offshore.

This solution favors a coastal front that will setup along I95 enhancing rainfall from Sat night - Monday as the low will track north.  The low strengthens to near 992 before hitting eastern Long Island by Tuesday morning.  This solution spells out significant wind and rain for the east coast while the Ohio Valley and Tenn Valley will undergo negative vorticity advection clearing out by Monday.

The EURO Solution ( NOT A BIG DEAL STORM)

The EURO plays along with the GFS, CMC, and NAM solutions right into Saturday morning.  Positive vorticity advection will be ongoing Saturday afternoon the shortwave deepens over the southern TN valley.  Severe weather will be likely Saturday morning for AL,MS,GA,SC, into Saturday afternoon as the vort max swings east.  The difference comes as the storm tries to lift north.  THERE IS NO PHASE! The north jet pulls north as the low continues its trick ENE.  A phase eventually happens 200 miles east of Cape Cod.




It is hard to come to a correct solution right now from VA - VT however, enough evidence is there to suggest a severe weather situation for Sat-Mon over the SE USA.  Including TN,VA,SC,NC,AL,MS, GA.


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