Mesoscale Discussion 1339
   NWS Storm Prediction Center Norman OK
   0723 PM CDT Sat Jul 25 2020

   Areas affected...the lower Texas Coastal Plain vicinity

   Concerning...Severe potential...Watch possible 

   Valid 260023Z - 260530Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Transient, weak rotation has been noted in cells
   associated with outer bands of Hurricane Hanna this evening. This
   activity will likely continue into the overnight hours.

   DISCUSSION...Over the last hour or so, transient rotating cells have
   been noted in an intense outer band of Hurricane Hanna. As of 00z,
   this band was located about 30 miles offshore the barrier islands of
   the Lower TX Coast, and generally shifting toward the coast at
   around 8-10 kt. 0-1 km SRH will increase this evening into the
   overnight hours as the center of Hanna shifts west/southwest toward
   the lower Rio Grande River, resulting in backing low level wind
   profiles. This could support a few transient rotating cells capable
   of a brief tornado or two over the lower coastal plain. 

   Additional cells further north closer to Corpus Christi have also
   shown some weak and transient rotation recently. Low level winds are
   still from the east/northeast, but will continue to become more
   east/southeasterly with time. Most recent velocity data from KCRP
   shows rotation is fairly shallow. Nevertheless, a brief spin-up
   cannot be ruled out given strong low level shear and enhanced SRH.
   At this time, it does not appear a tornado watch is needed
   imminently, but convective trends will be monitored closely and a
   watch may be possible this evening or during the overnight hours.

   ..Leitman/Guyer.. 07/26/2020

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

   ATTN...WFO...CRP...BRO...

   LAT...LON   26969714 27419711 27629707 27759711 27869725 27859760
               27749782 27589798 27269799 26649793 26149783 25939772
               25859747 25809719 25909707 26149699 26799714 26969714