NY NJ PA Weather Forecasts

Evening Thoughts: Heavy snow depends on mesoscale banding

9:30 PM

This evening I am in a waiting pattern before issuing any new snow maps at this time.  Through the day, the 12Z and 18Z model guidance has illustrated a potential limiting factor in the development of this dangerous winter storm.  The 12Z and 18Z GFS/NAM solutions basically follow the idea of the 700 MB low developing in such a way where heavy precipitation falls over the Baltimore metropolitan area and southern New England, yet lower QPF amounts for New York City.  The other feature is the development of mesoscale banding that reaches an apex over south-central New Jersey and then redevelops with increased mid level frontogenesis for Connecticut and the rest of the Southern New England.

What these two models are showing is the impact of strong lifting to the south and then north of the New York City metropolitan area, which leads to significantly less snowfall.  However, I stress that the way the mesoscale banding, especially the deformation zone, develops is very much uncertain and a rather fluid forecasting situation.  The location of this intense band, which on guidance produces up to two inches of liquid precipitation and up to two feet of snow, can just as easy develop over much of the New Jersey coast and the New York City metropolitan area.

So for now, I am going to take a wait and see approach with the 00Z guidance and then update appropiately for tomorrow morning, in which I’ll have an updated snowfall map and a break down of what to expect from this storm.

Regardless of the development of the 700 MB low, heavy snow is expected throughout much of the northern Mid Atlantic.  Strong wind gusts along the coast, will significantly reduce visibility and produce near blizzard conditions.

More on this dangerous storm for tomorrow morning!