ZCZC SPCSWOMCD ALL
ACUS11 KWNS 112244 
SPC MCD 112244 
CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-120015-

Mesoscale Discussion 1490
NWS Storm Prediction Center Norman OK
0544 PM CDT Wed Aug 11 2021

Areas affected...Eastern PA into Southern NY...NJ...MD...and DE

Concerning...Severe Thunderstorm Watch 427...

Valid 112244Z - 120015Z

The severe weather threat for Severe Thunderstorm Watch 427
continues.

SUMMARY...Strong to severe storms capable of damaging winds
continue. A local extension of WW427 maybe required across portions
of NJ and DE this evening.

DISCUSSION...A cluster of thunderstorms with a history of wind
damage across southern PA will continue to pose a risk for damaging
wind gusts this evening. Ongoing within an unstable (2000-3000 J/kg
of MLCAPE) but weakly sheared environment (<20 kts of effective
shear), convection has remained marginally organized in several
bands of multicell storms. Recent radar trends show additional
convective development ahead of the main band across northwestern NJ
suggesting storms will likely continue to the Atlantic coast. With
strong instability in place robust updrafts capable of strong
outflow winds appear likely. A local watch extension across NJ may
be required as storms approach the eastern edge of WW427 in the next
hour or two. 

Farther north across southern NY, isolated severe storms have
continued with a few instances of damaging wind gusts over the last
couple of hours. Storms have generally shown less organization
casting uncertainty on the severe threat for the remainder of the
evening. As such, a few severe storms will remain possible but
coverage is expected to remain low enough that a watch is unlikely.

..Lyons/Goss.. 08/11/2021

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

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

LAT...LON   40747603 41477497 41687421 41597358 41457347 41227353
            40847378 40057400 39597418 39347456 39257501 39417577
            39557621 39757646 40167648 40747603 

NNNN