Mesoscale Discussion 1457
NWS Storm Prediction Center Norman OK
0132 PM CDT Tue Jul 12 2022
Areas affected...Portions of eastern NY into New England
Concerning...Severe Thunderstorm Watch 460...
Valid 121832Z - 122000Z
The severe weather threat for Severe Thunderstorm Watch 460
continues.
SUMMARY...A threat for damaging winds and hail should spread
eastward this afternoon. An areal extension of Severe Thunderstorm
Watch 460 and/or a downstream watch may be needed.
DISCUSSION...Convection has gradually intensified over the past hour
or so across eastern NY. Strong effective bulk shear of 50+ kt
associated with an enhanced mid-level jet remains more than
sufficient for supercells, with multiple attempts at discrete
thunderstorms noted. Even with mid-level lapse rates remaining poor,
diurnal heating of a moist low-level airmass has contributed to
around 500-1000 J/kg of MLCAPE in a narrow corridor along and just
ahead of the ongoing activity. Some recent clustering has also
occurred in far eastern NY, and current expectations are for a mix
of multicells and supercells to spread eastward into parts of New
England over the next few hours. Both damaging winds and hail should
remain a threat with this activity. Based on current thunderstorm
motions around 35-40 kt, an areal extension of Severe Thunderstorm
Watch 460 to include more of eastern NY and southern VT may be
needed. A downstream watch into parts of New England where
sufficient destabilization has occurred is also possible.