Mesoscale Discussion 1335
   NWS Storm Prediction Center Norman OK
   0659 AM CDT Sat Jul 25 2020

   Areas affected...Middle and Upper Texas Coast

   Concerning...Severe potential...Watch possible 

   Valid 251159Z - 251400Z

   Probability of Watch Issuance...40 percent

   SUMMARY...The tornado threat will gradually increase this morning as
   tropical cyclone Hanna approaches the lower Texas Coast. A Tornado
   Watch may be necessary later this morning for portions of the Texas
   coast.

   DISCUSSION...Low-level helicity continues to slowly increase this
   morning across portions of the middle and upper Texas coast as
   tropical cyclone Hanna approaches. On the northwest side of Hanna,
   northerly shear has generally restricted the ability of feeder bands
   to sustain themselves and penetrate inland. Recent radar and
   satellite trends, however, suggests an uptick in convective vigor in
   several bands to the east and southeast of Galveston, including
   episodic areas of weak, broad low-level rotation embedded within the
   more pronounced/robust updrafts to the southeast of Galveston. 

   The commencement of diurnal heating to the north of the rain-filled
   central dense overcast, combined with an increase in low-level
   theta-e, should provide an increasingly favorable environment for
   sustaining vigorous convection. At this time the most likely area
   for this to occur will be across the northwest Gulf of Mexico, to
   the north of the main core of Hanna. These storms will continue to
   move to the west-northwest, impacting the middle and upper Texas
   coast through the morning. With time, low-level wind fields should
   strengthen in response to Hanna, resulting in an increasingly
   supportive environment for tornadoes. Although a tornado watch is
   not likely in the near term, one may be needed later this morning.

   ..Marsh/Edwards.. 07/25/2020

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

   ATTN...WFO...LCH...HGX...CRP...EWX...

   LAT...LON   29719685 30299508 29979439 29299441 28869528 28359632
               27969679 28049753 28749770 29719685