Storm Prediction Center Mesoscale Discussion 1939

   Mesoscale Discussion 1939
   NWS Storm Prediction Center Norman OK
   0712 PM CDT Tue Aug 11 2026

   Areas affected...Southeast Kentucky into northeast Tennessee

   Concerning...Severe Thunderstorm Watch 568...571...

   Valid 120012Z - 120215Z

   The severe weather threat for Severe Thunderstorm Watch 568, 571
   continues.

   SUMMARY...A weakening trend is noted in eastern portions of an MCS;
   the severe threat in the next 1-2 hours will be mainly concentrated
   on the western half of the line across southern Kentucky into
   northeast Tennessee.

   DISCUSSION...MRMS echo tops and lightning counts have been steadily
   declining within the eastern half of an MCS across southern WV and
   into western VA as the squall line continues to migrate into a more
   cool/stable environment. The severe threat from this portion of the
   line should continue to steadily decline with the coming onset of
   nocturnal cooling. Heading into the evening hours, the severe threat
   should remain concentrated across western portions of the MCS over
   southern KY and into east/northeast TN. Here, downstream
   temperatures remain in the low to mid 80s with MLCAPE values near
   2000 J/kg, and forcing along the outflow boundary will continue to
   promote additional thunderstorm development with some attendant
   damaging wind threat for at least the next couple of hours. However,
   the downstream KMRX VWP is currently sampling somewhat weaker
   deep-layer wind shear compared to other locations further upstream
   prior to the MCS passage. This suggests that the line may become
   increasingly outflow dominant. Additionally, the coming onset of
   nocturnal cooling should also contribute to a gradual weakening
   trend beyond roughly 01 to 02 UTC, which appears to be reflected
   well by recent HRRR/RRFS time-lagged solutions.

   ..Moore.. 08/12/2026

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

   ATTN...WFO...GSP...MRX...JKL...LMK...OHX...

   LAT...LON   37288482 37078407 36858340 36858326 36838290 36728251
               36548223 36338208 36038196 35868201 35668241 35558289
               35538333 35578377 35638405 35728430 35838456 36038481
               36298497 36728516 36948524 37168512 37288482 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN