Mesoscale Discussion 0466
   NWS Storm Prediction Center Norman OK
   0109 AM CDT Thu Apr 29 2021

   Areas affected...northeast Texas into southwest Arkansas

   Concerning...Tornado Watch 121...

   Valid 290609Z - 290815Z

   The severe weather threat for Tornado Watch 121 continues.

   SUMMARY...The threat for severe weather continues over eastern parts
   of watch 121, and may persist toward the Arklatex area, and a new
   watch may be needed.

   DISCUSSION...Numerous thunderstorms currently extend from northern
   AR into southeast AR and into north TX, along and ahead of the
   outflow-composite cold front. Surface analysis shows upper 60s to
   lower 70s F dewpoints over northeast TX and into southwest AR,
   contributing to around 1500 J/kg MLCAPE. Deep-layer shear remains
   favorable for organized storms as well, with 50-60 kt. In addition,
   effective SRH remains substantial with 300 m2/s2 over much of the
   area. The favorable shear may sustain storms over the next several
   hours, despite a minor warm layer near 700 mb.

   Various strong storms along the front may yet become severe as they
   evolve ahead of the cold front. Though storm mode is mixed, at least
   brief supercells are possible, with tornado threat. Given that the
   threat may persist beyond the typical 2-hour watch extension period,
   a new watch may be considered.

   ..Jewell.. 04/29/2021

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

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

   LAT...LON   32079517 31849679 31999721 32399731 32979679 33989632
               34359614 34859556 35299482 35389378 35199331 34959312
               34329317 32949375 32229460 32079517