12:00 PM | *Coastal storm threat continues for the middle of next week*

Discussion

The latest (12Z) run of the Global Forecast System (GFS) computer forecast model has backtracked somewhat from its previous couple of runs with respect to a potential significant midweek coastal storm in that it now phases a strong northern system with a potent southern system at a slower pace which allows the storm to form slightly farther to the east. There is still plenty of time to go; however, for this particular model to get back to a sooner phasing of energy and other forecast models do suggest that there will be a quicker phasing of these waves resulting in quite a rapidly intensifying coastal storm by the middle of next week – just in time for pre-Thanksgiving Day travel time period. The GFS forecast model is, in fact, known for a southeast bias with respect to coastal storm tracks so I wouldn't be surprised if it were to shift the track back to the west and we’ll monitor it closely. [12Z GFS 500 mb forecast map (above) showing both systems is for next Wednesday morning, courtesy weather.cod.edu)

The overall synoptic pattern shaping up for next week certainly suggests that there is potential for a significant coastal storm. First, a strong system will be moving eastward in the northern branch of the jet stream and it will be associated with an influx of fresh cold air. Second, a potent upper level low will be crossing the Gulf of Mexico and once this fresh cold air mass interacts with the southern system, rapid intensification of low pressure should take place near the Mid-Atlantic coastline. In addition, if you then throw in copious amounts of Gulf of Mexico moisture that will be available, this potential storm could turn out to be quite a precipitation producer even including thunderstorms in the vicinity of the low pressure system.

As far as precipitation-type is concerned, climatology is indeed one factor against snow in the I-95 corridor this time of year; specifically, with regard to the still-warm Atlantic Ocean waters. While odds do favor rain along the coast and inland back to the I-95 corridor big cities, it is still a close call and, if the phasing is just right, snow could be the result around here or perhaps there may be a “rain changing to snow” scenario. Accumulating snow is quite possible just to the north and west of the big cities in the colder higher elevation locations. Stay tuned.