The National Weather Service’s Storm Prediction Center (SPC) is warning about the possibility of severe weather in portions of the northeast on Friday. According to their latest Convective Outlook, there is a risk of thundershowers across the entire eastern U.S. on Friday, but there’s an elevated risk of severe thunderstorms across portions of Pennsylvania, New Jersey, Connecticut, New York, Massachussetts, and New Hampshire.
An upper-level trough is forecast to move eastward into the Northeast on Friday, as a cold front moves southeastward across the region; this will set the stage for severe weather to blossom across the region . Surface dewpoints ahead of the front are forecast to be in the mid 60s F, which will result in a narrow corridor of instability in the central and northern Appalachians. As surface temperatures warm, thunderstorms will likely form in the higher terrain around midday, with several small clusters moving eastward into the lower elevations during the afternoon.
According to the SPC, there is some disagreement concerning how much instability will develop across the northeast on Friday, according to computer forecast models. More aggressive solutions suggest that moderate instability could be in place ahead of the front by mid afternoon. Forecast soundings that show moderate instability, have veered winds and steep lapse rates at low-levels, and moderate to strong deep-layer shear. These soundings would support a severe threat with either large hail or wind damage possible. The severe threat would be concentrated near and after peak heating as instability maximizes during the late afternoon.
The National Weather Service may issue Severe Thunderstorm Watches ahead of this severe weather threat on Friday. When severe cells develop, Severe Thunderstorm Warnings will be issued for the counties impacted by severe weather conditions. For a thunderstorm to be classified as severe, it must have wind gusts over 58 mph and/or is producing hail that is an inch or larger wide.
