Storm Prediction Center Mesoscale Discussion 1702

   Mesoscale Discussion 1702
   NWS Storm Prediction Center Norman OK
   0657 PM CDT Tue Jul 21 2026

   Areas affected...Portions of northern Virginia into southern
   Maryland

   Concerning...Severe Thunderstorm Watch 509...

   Valid 212357Z - 220200Z

   The severe weather threat for Severe Thunderstorm Watch 509
   continues.

   SUMMARY...Thunderstorms approaching from the west will pose an
   increasing risk of damaging wind gusts and possibly a tornado or two
   across portions of northern Virginia this evening.

   DISCUSSION...A cluster of thunderstorms is crossing the high terrain
   of eastern WV and western VA this evening, aided by an MCV in
   Rockingham County VA. As these storms continue eastward across
   northern VA during the next few hours, a relatively warm and moist
   air mass and 40-50 kt of 0-6 km shear (per LWX VWP) may promote
   re-intensification into organized clusters and possibly supercell
   structures. This would favor an increasing risk of damaging wind
   gusts (especially if a north/south-oriented cold pool/gust front can
   evolve). Additionally, a gradually strengthening low-level jet and
   resultant increase in low-level hodograph curvature could support a
   brief tornado risk as well. Parts of Severe Thunderstorm Watch 509
   may eventually need to be extended in time, or a new watch may be
   needed.

   ..Weinman.. 07/21/2026

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

   ATTN...WFO...AKQ...LWX...

   LAT...LON   37767757 37987852 38197896 38517901 39067861 39137817
               39027741 38797685 38477673 37837701 37767757 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN