Storm Prediction Center Mesoscale Discussion 478

   Mesoscale Discussion 0478
   NWS Storm Prediction Center Norman OK
   0142 AM CDT Sat Apr 19 2025

   Areas affected...Eastern Oklahoma...Northwest
   Arkansas...South-central and Southeastern Missouri

   Concerning...Severe Thunderstorm Watch 143...

   Valid 190642Z - 190845Z

   The severe weather threat for Severe Thunderstorm Watch 143
   continues.

   SUMMARY...A severe threat is expected to continue overnight from
   eastern Oklahoma northeastward into southeast Missouri. Large hail
   and severe wind gusts will be the primary threats, but a tornado
   will also be possible. Weather watch issuance, or a local extension
   may be needed to the east of the ongoing watch near the 08Z watch
   expiration.

   DISCUSSION...The latest water vapor imagery shows a large area of
   convection located from northeast Oklahoma northeastward into the
   mid Mississippi Valley. This convection is located within southwest
   flow aloft near and to the west of a boundary. RAP analysis shows a
   low-level jet to the southeast of this convection over the
   Ark-La-Tex. Over the next few hours, storm development will be
   favored along the northwestern edge of the low-level jet from
   northwestern Arkansas into southern Missouri. The latest WSR-88D VWP
   at Springfield has strong shear with 0-6 km shear near 65 knots, and
   0-3 storm-relative helicity around 400 m2/s2. This will likely
   support an isolated severe threat over the next couple of hours.
   Although isolated supercells will be possible, the mode may tend to
   favor short line segments, especially as instability weakens
   gradually. Large hail and severe gusts will be the primary threats,
   but a tornado will also be possible. As the expiration of WW 143
   approaches, either a local extension or new watch will need to be
   considered.

   ..Broyles.. 04/19/2025

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

   ATTN...WFO...PAH...LSX...LZK...SGF...TSA...

   LAT...LON   35839554 35369568 34999535 34899446 36229229 36749115
               36959090 37239074 37569073 37849095 38039123 38099148
               38049198 37729265 36759437 35839554 

   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN