US Mesoscale Discussions

Storm Prediction Center Mesoscale Discussion 1218



   Mesoscale Discussion 1218
   NWS Storm Prediction Center Norman OK
   0310 PM CDT Sun Jun 09 2024

   Areas affected...parts of northwestern through north central
   Arkansas

   Concerning...Severe potential...Watch possible 

   Valid 092010Z - 092215Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Intensifying convection, including one or two storms at
   least occasionally taking on supercell structure, appears likely
   through 4-6 PM CDT.  This may pose a risk for large hail, locally
   damaging wind gusts and perhaps some potential for producing a
   tornado.

   DISCUSSION...Deepening convective development, including recent
   initiation of thunderstorm activity, is ongoing northwest of
   Russellville AR.  This is where low-level convergence has become
   maximized near the intersection of a southward advancing cold front
   and the stalling western flank of convective outflow from overnight
   convection.

   Beneath 30-35 kt west-northwesterly flow around 500 mb, surface
   temperatures are warming through the lower/mid 90s F in a narrow
   corridor just to the southwest of the outflow boundary, extending
   across and east-southeast of the Little Rock area.  This is
   occurring beneath a remnant plume of elevated mixed-layer air, where
   seasonably high boundary-layer moisture content appears to be
   contributing to mixed-layer CAPE on the order of 2000-3000 J/kg.

   It is possible that this is being aided by forcing for ascent
   associated with a subtle mid/upper perturbation.  Regardless, there
   appears sufficient deep-layer shear to support intensifying
   convection and the evolution of at least transient supercell
   structures with increasing inflow of the unstable boundary-layer
   air.  This likely will pose a risk for severe hail, locally strong
   surface gusts and perhaps at least some risk for a tornado while
   slowly propagating east-southeastward through 4-6 PM CDT.

   ..Kerr/Gleason.. 06/09/2024

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

   ATTN...WFO...MEG...LZK...TSA...

   LAT...LON   35829425 35949391 36079321 35819217 35339092 34389147
               35079328 35209385 35479434 35829425 



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