Mesoscale Discussion - Tornado Watch Unlikely

 

Mesoscale Discussion 2065

   NWS Storm Prediction Center Norman OK

   1221 PM CDT Fri Sep 13 2024

   Areas affected...Parts of AL into middle TN

   Concerning...Severe potential...Watch unlikely 

   Valid 131721Z - 131945Z

   Probability of Watch Issuance...20 percent

   SUMMARY...The threat for locally damaging wind and possibly a

   tornado may increase into this afternoon.

   DISCUSSION...A remnant surface low is located over northern AR early

   this afternoon. An occluded front extends east-northeast of the low

   into western TN, then extends southeast as a stationary or warm

   front across parts of northern/central AL into western GA. Farther

   south, a cold front is moving across MS, with a surface trough/wind

   shift noted to the east from western AL into southern MS. 

   In the vicinity of these boundaries, convection is gradually

   increasing from western AL into southern middle TN, and a few cells

   across northwest AL have exhibited some weak rotation. While

   low-level flow/shear has gradually decreased as the remnant of

   Tropical Cyclone Francine has weakened, effective SRH of around 100

   m2/s2 and modestly favorable deep-layer shear will continue to favor

   occasionally organized convection into this afternoon. MLCAPE will

   increase to near or above 1000 J/kg, with an increase in convective

   coverage expected with time within a weakly capped environment.

   A few marginal supercells could evolve with time, and a tornado

   cannot be ruled out, especially in a zone between the surface

   trough/wind shift approaching from the west and the effective warm

   front to the east, where low-level flow will remain locally backed

   as gradual heating/destabilization continues. Otherwise, locally

   damaging winds will be possible, especially if any localized

   clustering of convection can develop with time.

   ..Dean/Gleason.. 09/13/2024

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

   ATTN...WFO...OHX...BMX...HUN...MOB...MEG...

   LAT...LON   32228565 31618689 31888728 32568749 34138797 34948822

               35448837 35718835 35898821 36088759 36108707 35658637

               33948592 32638572 32228565