The Storm Prediction Center has again placed western and interior portions of the NYC region under a slight risk for severe weather today. The atmospheric setup this afternoon is similar to yesterday, with plenty of solar heating and humid air leading to moderate instability. At this hour, CAPE values (a measure of instability) are already hitting 1500-2500 J/Kg across the area, with greater instability further south.

There are already a few scattered thunderstorms forming over Eastern Pennsylvania. These storms are not yet hitting severe limits, but conditions are favorable for further development and increase in areal coverage. With winds aloft mostly unidirectional from the southwest, damaging wind gusts would be the primary threat. Storms that form to the southwest of NYC near the Philadelphia metro area and Central New Jersey would be the ones to watch for immediate impacts in the city.

These storms are still several hours away, and it remains to be seen whether they will hold up upon encountering the cooler and stabilizing influence of marine air infiltrating along south-facing shores with the southwest winds and a sea breeze. Last night, the line of severe thunderstorms weakened just before it hit NYC, sparing us from some wicked weather for the night. The same case may unfold again today, but the situation bears monitoring.