Storm Prediction Center Mesoscale Discussion 906

   Mesoscale Discussion 0906
   NWS Storm Prediction Center Norman OK
   0148 PM CDT Tue May 20 2025

   Areas affected...Northern Alabama...middle Tennessee...and
   south-central Kentucky

   Concerning...Severe potential...Watch likely 

   Valid 201848Z - 202045Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A tornado watch downstream of WW 303 is expected in the
   next hour or so as T-storms spread from northern MS and western TN
   into northern AL, middle TN, and southern KY.

   DISCUSSION...Sustained convective initiation is well underway across
   central AR to northern MS/western TN as thunderstorms develop along
   a cold front and within the open warm sector due to modest low-level
   warm air advection. This activity is expected to intensify through
   late afternoon and will gradually spread east. Storm-track
   projections suggest that the eastern most storms across northern
   MS/western TN should exit WW 303 by around 20 UTC and spread across
   much of northern AL and middle TN through 00 UTC. Much of northern
   AL was glanced by early-morning/early-afternoon convection, but the
   region largely remains supportive of deep convection with buoyancy
   characterized by 1500-2000 J/kg MLCAPE. Further north across
   northern middle TN into southern KY, a residual cold pool associated
   with a late-morning QLCS has significantly limited buoyancy for the
   time being. However, 30-35 knot southwesterly flow between 925-850
   mb will advect warm/moist air into the region and promote
   destabilization through late afternoon. (Warm advection is already
   noted on the KOHX VWP between 0-2 km.) Deep-layer wind shear across
   the region should increase through late afternoon as a mid-level jet
   approaches the region and maintains the potential for severe
   convection, which will likely be a combination of organized lines
   and supercells.

   Watch issuance is expected in the next hour or so to address this
   concern, though earlier watch issuance is possible if open warm
   sector convection can develop across northern AL and pose a severe
   threat in the short-term.

   ..Moore/Hart.. 05/20/2025

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

   ATTN...WFO...MRX...FFC...LMK...OHX...BMX...HUN...PAH...MEG...
   JAN...

   LAT...LON   33728825 34928796 36778803 37058803 37198777 37308666
               37258613 37118588 36698575 34848558 34108574 33738608
               33468667 33398732 33418786 33548814 33728825 

   MOST PROBABLE PEAK TORNADO INTENSITY...120-150 MPH
   MOST PROBABLE PEAK WIND GUST...75-90 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN