Stormy night for mid atlantic / northeast
A strong Disturbance has enhanced a trough sitting over central PA which has sparked strong/severe storms in W/C PA and throughout the region. Instability is very high in PA and much of new jersey with marginal wind shear supportive of such storms.notice the lifting index which is the temp difference from the surface to 500mb , the higher the negative number the more unstable the atmosphere is. meanwhile the frontal boundary that has lifted into the eastern great lakes is now moving back southeast with a very intense line of severe storms and tornadoes in certain parts of C NY. it is there that the instability and strongest wind shear is present around the mohawk river valley
as the frontal boundary drops to the southeast and closer to the coast around the nyc metro area and especially LI the intensity of these storms will rapidly decrease or just simply collapse. why? refer back to the surface based lifting index, it is there you can see the atlantic influence.
for the rest of the evening and tonight expect showers and storms some severe especially over C NY , C/E PA , hudson river valley , NW NJ. there are some model guidance that suggest the 850mb LLJ will intensify ahead of the frontal boundary and keep some of these storms severe.
(forecaster , steve ) twitter SteveGwx