Storm Prediction Center Mesoscale Discussion 2120

   Mesoscale Discussion 2120
   NWS Storm Prediction Center Norman OK
   0539 PM CDT Thu Sep 26 2024

   Areas affected...from Jacksonville northward across much of
   southeast Georgia and the Carolinas

   Concerning...Tornado Watch 684...

   Valid 262239Z - 270315Z

   The severe weather threat for Tornado Watch 684 continues.

   SUMMARY...The risk of tornadoes is likely to increase/spread
   northward through tonight across southeast Georgia, eastern South
   Carolina and southeast North Carolina. An isolated strong tornado
   cannot be ruled out.

   DISCUSSION...Surface analysis shows a warm front/boundary from
   southern GA to just off the SC Coast this evening. South of this
   boundary, deeper tropical moisture exists with upper 70s F to near
   80 F dewpoints, and as such, MLCAPE near the coast is already near
   1000 J/kg, with larger values over 1500 J/kg off the eastern FL
   Peninsula.

   As Hurricane Helene continues northward this evening, wind fields
   across the region will strengthen, with 850 mb winds increasing
   dramatically after about 03Z. As such, the surface warm front will
   move ashore into SC, with further destabilization over parts of
   southeast GA as well. 

   Effective SRH of 300-500 m2/s2 coincident with the instability axis
   will be common this evening, with even stronger shear but lower
   instability along the western fringe of the warm sector.

   An initial band of convection currently extends into the
   Jacksonville FL area, and embedded cells could rotate an produce a
   brief tornado. Additional bands of storms are likely to develop this
   evening and tonight as the warm advection processes increase. Given
   such strong shear, an isolated strong tornado cannot be ruled out
   late.

   ..Jewell.. 09/26/2024

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

   ATTN...WFO...MHX...RAH...ILM...CHS...CAE...JAX...FFC...

   LAT...LON   31907960 31088013 30598032 30148070 30028098 30028114
               30378167 30598227 30838293 31168292 31708266 32898197
               33368153 33958106 34827946 34867847 34767791 34337752
               34057749 33697764 32917843 32497896 31907960