Mesoscale Discussion 0330
NWS Storm Prediction Center Norman OK
0233 PM CDT Mon Mar 31 2025
Areas affected...Northern Virginia into central Maryland...southeast Pennsylvania...and northwest New Jersey
Concerning...Severe potential...Watch possible
Valid 311933Z - 312130Z
Probability of Watch Issuance...40 percent
SUMMARY...Thunderstorm development is expected within the next
couple of hours across parts of the Mid-Atlantic region. The
convective environment should support a damaging wind threat into
the evening hours. Trends will be monitored for possible watch
issuance.
DISCUSSION...Over the past few hours, GOES visible imagery has shown
a gradual increase in agitated cumulus within a deepening trough
axis in the lee of the central Appalachians. Steady diurnal heating
under broken cloud cover has allowed temperatures to warm into the
upper 70s to low 80s - a few degrees warmer than anticipated by
recent guidance, which suggests that thunderstorm initiation should
become increasingly probable in the next couple of hours. Buoyancy
on the northern periphery of returning moisture appears to be meager
due to somewhat poor mid-level lapse rates and overall low quality
moisture. This will modulate updraft intensities to some degree, but
strong speed shear noted in upstream VWPs should help promote
longevity of initially semi-discrete cells. Mean wind and deep-layer
shear vectors oriented along the lee trough axis will likely promote
upscale growth with time and perhaps an increasing damaging wind
threat as cold pools amalgamate within an environment featuring
low-level lapse rates between 7-8 C/km. Convective trends will
continue to be monitored, and watch issuance is possible if/when
thunderstorm development becomes more imminent and storm coverage
becomes sufficient for a more widespread threat across the region.