ZCZC SPCSWOMCD ALL
ACUS11 KWNS 231652 
SPC MCD 231652 
MSZ000-ARZ000-LAZ000-231845-

Mesoscale Discussion 0124
NWS Storm Prediction Center Norman OK
1052 AM CST Sat Feb 23 2019

Areas affected...central and northern LA...southeast AR...central
and northern MS

Concerning...Severe potential...Tornado Watch likely 

Valid 231652Z - 231845Z

Probability of Watch Issuance...95 percent

SUMMARY...A tornado watch will likely be needed between 12-1pm for
LA into portions of AR and MS.  One or two tornado watches will
likely be required by early afternoon over the lower MS Valley
region.

DISCUSSION...Radar mosaic shows a weak squall line developing over
northwest LA into southwestern AR.  The squall line is co-located
with the Pacific front/dryline over the Sabine Valley.  Visible
satellite imagery shows a broken cumulus field from northeast LA
through MS where surface heating is contributing to temperatures
rising into the lower to middle 70s degrees F.  

The 9am Univ. Louisiana Monroe special Vortex2SE sounding showed a
residual capping inversion near 700mb.  The capping inversion has so
far impeded sustained, free warm sector convective development to
the east of the squall line.  The 14.1 g/kg lowest 100mb mean mixing
ratio indicative of a very moist airmass beneath 8.7 degree C/km
700-500mb lapse rates, are suggestive of moderate buoyancy
developing this afternoon as temperatures gradually warm through the
middle 70s.  Some slight cooling of mid-level temperatures
---reducing the effects of a warm layer noticed above 500mb in the
Monroe, LA sounding--- may occur during the next few hours and
further contribute to destabilization.

Strengthening mid-to high-level flow fields this afternoon will
promote storm organization with a favored tendency for supercells
with updrafts not located within a cold pool-forced ascent regime
(i.e., squall line).  As such, strong low-level shear will
potentially favor strong low-level mesocyclone rotation with the
more robust/discrete updrafts.  A couple of tornadoes, in addition
to damaging winds, are the primary hazards.

..Smith/Grams.. 02/23/2019

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

ATTN...WFO...MEG...JAN...LIX...LZK...LCH...SHV...

LAT...LON   33179283 34359125 34499046 34238970 33538917 32638932
            30889133 30819245 31289328 32059344 33179283 

NNNN