US Mesoscale Discussions

Storm Prediction Center Mesoscale Discussion 738

Mesoscale Discussion



   Mesoscale Discussion 0738
   NWS Storm Prediction Center Norman OK
   0803 PM CDT Thu May 09 2024

   Areas affected...portions of central and eastern Texas into western
   and northern Louisiana

   Concerning...Severe Thunderstorm Watch 222...224...

   Valid 100103Z - 100230Z

   The severe weather threat for Severe Thunderstorm Watch 222, 224
   continues.

   SUMMARY...The severe threat continues across Severe Thunderstorm
   Watches 222 and 224. Severe winds and hail remain the primary
   threats. Conditions are being monitored for upscale growth into a
   bow echo and accompanying risk of a greater damaging wind threat.

   DISCUSSION...Multiple supercells with a history of producing severe
   hail (up to 4 inches in some cases) and isolated damaging gusts
   continue to progress southeast over central TX. These storms are
   impinging on a zonal baroclinic boundary, where additional storms
   have recently initiated. Given 4500+ J/kg MLCAPE and 50-70 kts of
   effective bulk shear in place, any supercells that remain discrete
   will continue to pose a damaging gust and large hail risk, including
   stones exceeding 2 inches in diameter.

   Of greater concern is the possibility of upscale growth into an
   organized bow-echo MCS, which could produce an appreciable swath of
   severe gusts (including those exceeding 75 mph) upon development.
   However, intense bow-echo development is conditional upon efficient
   cold pool mergers and the progressive cold pool boundary (convective
   leading line) becoming oriented roughly normal to the deep-layer
   shear vector. The latest high resolution model guidance, including
   the last few runs of the HRRR and Warn-on-Forecast ensemble output,
   lean against this scenario. Nonetheless, should storms remain more
   discrete, high-resolution guidance still suggests that at least some
   severe wind potential will continue into the evening hours, and a
   couple of 75+ mph gusts could still occur.

   ..Squitieri.. 05/10/2024

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

   ATTN...WFO...JAN...LCH...SHV...HGX...FWD...EWX...

   LAT...LON   30229880 31099820 32219481 32539331 32639179 32459177
               31799237 31039389 30569496 30089656 29869771 30229880 



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