Mesoscale Discussion 1669
   NWS Storm Prediction Center Norman OK
   1232 PM CDT Wed Sep 01 2021

   Areas affected...northeast Virginia into central and eastern
   Maryland

   Concerning...Tornado Watch 482...483...

   Valid 011732Z - 011930Z

   The severe weather threat for Tornado Watch 482, 483 continues.

   SUMMARY...A relative maximum in tornado risk currently stretches
   from northeast Virginia into central and eastern Maryland.

   DISCUSSION...Multiple supercells have developed within a line south
   of the D.C. area, with notable rotation on radar. The moist and
   warming air mass has lead to 2000-2500 J/kg SBCAPE, including a
   favorable amount of low-level CAPE as 700 mb temperatures remain
   tempered.

   The 16Z special sounding from IAD shows an impressive low-level
   hodograph structure, with observed storm motions resulting in 280
   m2/s2 0-1 SRH. As such, it appears RAP-based objective analysis is
   underestimating the shear.

   The environment east/northeast of the ongoing cells remains
   favorable for a supercell tornado threat, bounded on the north by
   the stationary front.

   ..Jewell.. 09/01/2021

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

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

   LAT...LON   39747586 39237587 38557604 38147626 37887676 37867701
               37977722 38387718 38757720 39277750 39567724 39777654
               39827618 39747586