Mesoscale Discussion 0463
   NWS Storm Prediction Center Norman OK
   0919 PM CDT Wed Apr 28 2021

   Areas affected...Eastern Oklahoma...western Arkansas...northeast
   Texas...and northwest Louisiana

   Concerning...Tornado Watch 121...

   Valid 290219Z - 290415Z

   The severe weather threat for Tornado Watch 121 continues.

   SUMMARY...The risk for severe weather continues across WW 121.
   Thunderstorms are expected to increase in coverage across the
   Arklatex region over the next few hours. Isolated severe storms are
   expected to continue across portions of central Oklahoma and
   north-central Texas.

   DISCUSSION...Recent regional radar trends have shown an increase in
   storm coverage across the Arklatex region, likely the result of
   increasing isentropic ascent between 850-700 mb. Storms will
   gradually become organized as they begin to mature in an environment
   characterized by 1000-1500 J/kg MLCAPE and 50-60 knots of effective
   bulk shear. Despite some boundary-layer stabilization, effective SRH
   values remain elevated between 200-400 m2/s2 from northeast TX into
   eastern OK/western AR. KSRX VWP observations support this idea with
   nearly 500 m2s2 0-1 km SRH noted, and a nearby supercell has taken
   on transient low-level rotation. As such, the tornado potential
   should continue over the next few hours for all of WW 121. 

   To the west, isolated supercells have developed along a weak cold
   frontal boundary from central OK into northern TX. Hail up to 2
   inches has been reported with some of this activity (particularly in
   the OKC metro area). This activity will likely persist as it
   translates eastward into a most unstable air mass, and will continue
   to pose a severe hail and wind risk. While one or two additional
   cells are possible, storm coverage should remain isolated enough to
   negate the need for an new watch.

   ..Moore.. 04/29/2021

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

   ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

   LAT...LON   32869769 34189677 35079594 35939476 35929388 35619356
               34829339 33999367 33199398 32749444 32489522 32339672
               32429744 32869769