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Mesoscale Discussion 1691
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   Mesoscale Discussion 1691
   NWS Storm Prediction Center Norman OK
   0216 PM CDT Tue Sep 15 2020

   Areas affected...Coastal Alabama and Florida

   Concerning...Tornado Watch 489...

   Valid 151916Z - 152115Z

   The severe weather threat for Tornado Watch 489 continues.

   SUMMARY...The tornado threat associated with several outer feeder
   bands of Hurricane Sally will likely increase this afternoon and
   evening. The current tornado watch will remain valid until around
   23Z when a new tornado watch will likely be coordinated.

   DISCUSSION...As of 2 pm CDT, the center of Hurricane Sally was
   located at 29.2N 88.2W or about 105 miles southwest of Mobile,
   Alabama from the latest NHC guidance. Several feeder bands are
   rotating around the storm, with embedded cellular convective
   elements noted. Additional small discrete cells were observed off
   the coast of the Florida, near Tallahassee. The wind field around
   Sally is forecast to continue to mature, and SPC mesoanalysis shows
   that strong 0-1 km shear of 50-60 kts is present in Sally's
   northeastern quadrant. Some dry air entertainment between the bands
   should support weak destabilization this afternoon and evening given
   the very moist surface conditions (TDs 75-79 degrees F). The
   increase in buoyancy and strong low-level shear should support small
   rotating updrafts with an attendant risk for tornadoes as the bands
   move ashore. The threat for tornadoes will increase further as Sally
   moves slowly to the north this evening and overnight, bringing
   stronger shear and convection onshore. Tornado Watch 489 remains
   valid until 2300 UTC when a new tornado watch will be coordinated.

   ..Lyons/Hart.. 09/15/2020

   ...Please see for graphic product...


   LAT...LON   29838551 29988571 30148609 30238658 30228692 30128745
               30088792 30168821 30378833 30648834 30838831 31138801
               31218764 31238713 31138619 30958541 30728480 30298411
               29758412 29668443 29568488 29598518 29838551 

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