Mesoscale Discussion 1391
   NWS Storm Prediction Center Norman OK
   0326 PM CDT Thu Jul 29 2021

   Areas affected...Southeastern PA...NJ...Northern VA...Central
   MD...Delmarva

   Concerning...Tornado Watch 401...

   Valid 292026Z - 292200Z

   The severe weather threat for Tornado Watch 401 continues.

   SUMMARY...Threat for damaging wind gusts and/or brief tornadoes will
   continue for the next few hours.

   DISCUSSION...A large area of showers and thunderstorms continues to
   move eastward across the northern Mid-Atlantic. Much of this
   activity has remained shallow and transient. However, a few more
   robust updrafts have been able to develop, including two which are
   currently ongoing over MD, one over Carroll County MD and the other
   over Howard County MD, and another over Lehigh County PA. Low to
   mid-level rotation has been noted in each one of these storms,
   suggesting the slightly stronger flow associated with this shortwave
   trough (sampled well by recent LWX VAD profiles) coupled with the
   southerly surface winds is enough to promote updraft rotation. This
   current trend of transient updrafts capable of damaging wind gusts
   and/or brief tornadoes will likely continue for the next few hours.

   ..Mosier.. 07/29/2021

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

   ATTN...WFO...OKX...PHI...CTP...LWX...

   LAT...LON   40877596 41147542 40787442 39667467 38997507 38787661
               39347758 40167678 40877596