Subj : MESO: Mesoscale Discussion 1158
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jun 18 2023 23:11:24

ACUS11 KWNS 182311
SWOMCD
SPC MCD 182311=20
MSZ000-LAZ000-ARZ000-190015-

Mesoscale Discussion 1158
NWS Storm Prediction Center Norman OK
0611 PM CDT Sun Jun 18 2023

Areas affected...Far Southeast Arkansas...Northeast
Louisiana...Western and Central Mississippi

Concerning...Severe potential...Tornado Watch likely=20

Valid 182311Z - 190015Z

Probability of Watch Issuance...80 percent

SUMMARY...A severe threat will likely develop across parts of the
lower Mississippi Valley early this evening. A potential for wind
damage, large hail and tornadoes are expected to develop. Weather
watch issuance will likely be needed.

DISCUSSION...Water vapor imagery currently shows west-northwesterly
mid-level flow over the lower Mississippi Valley, with a 700 mb
speed max of 40 to 50 knots located in southwest Arkansas. At the
surface, a trough is located from northeast Texas into south-central
Arkansas. Ahead of this feature, surface dewpoints are mostly in the
70s F. This is contributing to moderate to strong instability, with
the RAP estimating MLCAPE in the 3000 to 5000 J/kg range. In spite
of the instability, large-scale ascent is weak across much of the
region. However, as low-level convergence increases along the
surface trough and southward into northern Louisiana early this
evening, convective initiation will become likely. Based on cam
guidance, storms appear likely to initiate over the next couple of
hours. The 21Z sounding at Jackson, Mississippi has 0-6 km shear
near 60 kt with 0-3 km storm relative helicity near 400 m2/s2. As
the storms grow upscale, supercells with large hail and wind damage
will become likely. A tornado threat is also expected to develop.

...Broyles/Grams.. 06/18/2023

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!6F3jRJhPuHBxNeB-tIiXwSu5F7rvNKODXjqBdVGijk9pfw4UD567iTUtGlus7nLGPOamAAB0-=
jke3oCaTkImYFSzifw$  for graphic product...

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

LAT...LON   32019162 32159233 32339251 32659260 32939256 33179236
            33299191 33379080 33278986 33078962 32748952 32258961
            32078995 32029083 32019162=20


=3D =3D =3D
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