SPC MD 446

MD 0446 CONCERNING TORNADO WATCH 134...135... FOR ARKLATEX...SOUTHEAST OK

Mesoscale Discussion 0446
NWS Storm Prediction Center Norman OK
0639 PM CDT Wed Apr 22 2020

Areas affected...ArkLaTex...southeast OK

Concerning...Tornado Watch 134...135...

Valid 222339Z - 230045Z

The severe weather threat for Tornado Watch 134, 135 continues.

SUMMARY...Severe risk will likely shift out of WW134 and 135. A
continued risk of severe weather including tornadoes may require a
new watch or local extension.

DISCUSSION...Supercells with a history of producing tornadoes in
south/southeastern Oklahoma and near the Red River are moving toward
the eastern edge of WW134. Mesoanalysis shows previous convection
and stratiform rain have cooled and likely stabilized the boundary
layer across southern Arkansas with temperatures in the upper 50s
and low 60s. Further to the south across northeast Texas and
northwest Louisiana, temperatures and dewpoints have increased into
the 70s F and upper 60s F respectively.  Ahead of the surface
cyclone across Oklahoma, low level moisture and thermal advection,
as well as decreasing mid level temperatures with the shortwave
trough may offset the cooler boundary layer to destabilize this
region enough for a sustained severe threat. Elevated convection may
develop where surface temperatures remain too cool and a more
favored corridor of surface based storms is possible along the Red
River where area RAP soundings show MLCAPE increasing to 500-1500
J/kg. Strong effective shear of 50 to 60 kt would continue to
support mid level mesoscylones with the supercells currently ongoing
across Oklahoma. Large hail and damaging winds would be the main
threats as storms outrun the greater instability toward central
Arkansas, but a tornado or two will also be possible.  A new small
watch or local extension of a current watch may be needed.

..Lyons/Grams.. 04/22/2020

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

ATTN...WFO...LZK...SHV...TSA...

LAT...LON   34879471 34579362 33929305 33399295 33039352 32789402
            32719495 33269526 34879528 34879471 

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from SPC Forecast Products http://www.spc.noaa.gov/products/md/md0446.html