Storm Prediction Center Mesoscale Discussion 1872

   Mesoscale Discussion 1872
   NWS Storm Prediction Center Norman OK
   0338 AM CDT Fri Aug 09 2024

   Areas affected...southern Pennsylvania...northern
   Virginia...Maryland

   Concerning...Tornado Watch 615...

   Valid 090838Z - 091145Z

   The severe weather threat for Tornado Watch 615 continues.

   SUMMARY...The potential remains for brief tornadoes tonight, mainly
   from northern Virginia into southeast Pennsylvania.

   DISCUSSION...Surface analysis shows a warm front well into PA, where
   low-level winds remain backed and are now gusting to 25-30 kt out of
   the southeast. Theta-e has increased with the passage of the warm
   front, with mid 70s F dewpoints and temperatures of 77-80 F.
   Meanwhile, area VWPS indicate that low-level shear remains quite
   favorable for brief tornadoes, with 0-1 km SRH values over 200
   m2/s2.

   Recent radar trends indicate increasing storms just east of the low,
   where enhanced lift is interacting with the still warm and unstable
   air mass. Given current trends, growing showers could become
   supercells over the next several hours, with a tornado risk. In
   addition, other convection interacting with the warm front farther
   north may also attain rotation. As such, the tornado watch
   continues, and areas just north of the ongoing watch may need to be
   addressed later this morning as the air mass, and lift, remain
   favorable.

   ..Jewell.. 08/09/2024

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

   ATTN...WFO...PHI...AKQ...CTP...LWX...

   LAT...LON   38397820 38567829 39137844 39757818 40327756 40887605
               40807558 40537528 40177534 39427574 38677609 38307619
               37967685 37967722 38287796 38397820