Mesoscale Discussion 2070
   NWS Storm Prediction Center Norman OK
   0925 AM CST Wed Dec 29 2021

   Areas affected...portions of far southeast OK...northeast
   TX...southern AR...and northern LA

   Concerning...Severe potential...Watch possible 

   Valid 291525Z - 291730Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Severe thunderstorm potential is increasing across parts
   of the ArkLaTex vicinity. A watch may be needed by 17z.

   DISCUSSION...A quasi-stationary boundary extends from west to east
   across parts of far north Texas into southern AR and western TN at
   15z. Isolated, mainly elevated, thunderstorms are ongoing across
   eastern OK into north Texas along the Red River in a strong warm
   advection regime ahead of a surface low located northwest of the
   Dallas-Ft. Worth Metroplex. To the south of the boundary, surface
   dewpoints are mainly in the mid 60s to near 70 F. Steep midlevel
   lapse rates near 8.0 C/km were noted in the 12z FWD RAOB, with more
   modest values around 6.5-7 C/km noted downstream. Rich warm sector
   moisture beneath moderate midlevel lapse rates is resulting in
   MLCAPE values around 500-1000 J/kg already this morning. Visible
   satellite imagery also shows a broad, agitated CU field across the
   ArkLaTex vicinity with vertical development apparent in short-term
   loops. 

   Mid/upper forcing associated with an ejecting shortwave trough over
   the OK/TX Panhandles will remain somewhat limited. However,
   thunderstorm coverage is expected to increase by around 17-18z as
   the surface low develops eastward along the frontal wave and a 35-45
   kt low level jet overspreads the region. Effective shear magnitudes
   greater than 50 kt and favorably curved low-level hodographs will
   support isolated supercell structures capable of strong gusts and a
   tornado or two. Additionally, the KFWS VWP indicates an elongated,
   straight hodograph in mid and upper levels, and combined with
   moderate midlevel lapse rates, stronger storms may also produce
   severe hail. Convective trends are being monitored and a watch may
   be needed for portions of the MCD area in the next hour or two.

   ..Leitman/Hart.. 12/29/2021

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

   ATTN...WFO...JAN...LZK...SHV...

   LAT...LON   33079500 33629506 33859487 34009454 34279381 34379315
               34359250 34189206 33649171 33179175 32639210 32489267
               32459339 32509416 32659468 33079500