Mesoscale Discussion 1265
   NWS Storm Prediction Center Norman OK
   1232 PM CDT Mon Jul 12 2021

   Areas affected...Portions of the Northeast

   Concerning...Severe potential...Watch possible 

   Valid 121732Z - 121900Z

   Probability of Watch Issuance...60 percent

   SUMMARY...A few multicell clusters of storms should emerge by mid to
   late afternoon, posing a threat for damaging winds. Trends will
   continue to be monitored for a possible severe thunderstorm watch.

   DISCUSSION...Visible satellite shows morning clearing over the
   region has allowed surface temperatures to warm into the mid to
   upper 80s F amid dew point temperatures in the low 70s F. This has
   led to somewhat rapid destabilization, with moderate instability
   (MLCAPE 2000-2500 J/kg) being analyzed on surface mesoanalysis.
   Scattered convection is already developing across portions of
   southern Pennsylvania, western Maryland, and northern Virginia, as
   convective temperatures are being eclipsed amid a weak cap. Despite
   these thermodynamic indices, mid-level lapse rates and deep-layer
   shear remains rather weak (20-25 kt effective bulk shear). Thus,
   storms may struggle to organize in the short-term.

   Additional storms should develop across the region as
   isolation/destabilization continues. This should lead to the
   development of a few multicell clusters of storms this afternoon.
   Should this occur, strong low-level lapse rates should support a
   damaging wind potential. Thus, convective trends will continue to be
   monitored for possible watch issuance this afternoon.

   ..Karstens/Dial.. 07/12/2021

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

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

   LAT...LON   38357674 38277825 38917898 40467848 41157717 41387507
               40907296 39787391 38697498 38357674