612
ACUS11 KWNS 301356
SWOMCD
SPC MCD 301355
MAZ000-NHZ000-RIZ000-CTZ000-NYZ000-VTZ000-NJZ000-PAZ000-DEZ000-MDZ000-301600-

Mesoscale Discussion 1487
NWS Storm Prediction Center Norman OK
0855 AM CDT Sun Jun 30 2024

Areas affected...portions of the Mid-Atlantic and southern New
England

Concerning...Severe potential...Severe Thunderstorm Watch likely

Valid 301355Z - 301600Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorm coverage will gradually increase in
coverage/intensity through midday. Swaths of damaging wind gusts are
expected through afternoon. One or more severe thunderstorm watches
will likely be needed in the next couple of hours for portions of
the Mid-Atlantic into New England.

DISCUSSION...A very moist airmass is already in place across the
region this morning, with surface dewpoints in the low to mid 70s F
noted in observations. Temperatures are already in the upper 70s to
low 80s, and even modest heating through broken clouds will aid in
further destabilization toward midday. 12z RAOBs from ALB and OKX
also indicate a strongly sheared environment, with effective shear
magnitudes greater than 40 kt present. Early convection is already
noted near Binghamton NY along an outflow boundary. Additional
convection is developing further west across central PA ahead of an
east/southeast-advancing cold front.

As convection gradually increases over the next few hours, bowing
segments/clusters are expected given mostly unidirectional
deep-layer flow. Large instability, high PW values, and steepening
low-level lapse rates amid favorable shear will support swaths of
damaging winds across the region through the afternoon into early
evening. One or more watches will likely be needed for the region
within the next couple of hours.

..Leitman/Gleason.. 06/30/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...CTP...LWX...

LAT...LON   42087612 42887429 43017286 42997153 42917079 42557045
            41937050 41627060 40257239 39747343 39197460 39307544
            39417600 39867669 40327696 40717692 41487664 42087612