ACUS11 KWNS 190143
SWOMCD
SPC MCD 190143=20
ALZ000-TNZ000-MSZ000-190345-

Mesoscale Discussion 1160
NWS Storm Prediction Center Norman OK
0843 PM CDT Sun Jun 18 2023

Areas affected...western AL

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

Valid 190143Z - 190345Z

Probability of Watch Issuance...80 percent

SUMMARY...A risk for all hazards of severe weather appears to be
increasing across western AL. WW issuance is likely within the next
hour depending on ongoing convective trends.

DISCUSSION...Multiple supercells have developed across central MS
and are moving eastward through WW335. The 19/00z JAN sounding
featured an uncapped boundary layer with nearly 4000 J/kg of MLCAPE,
effective shear around 45 kts, and significant veering low-level
shear contributing to 455 J/kg of ESRH (along with 235 J/kg in the
lowest 1 km AGL). Despite generally weak synoptic forcing, these
supercells acquired mid- and low-level mesocyclones rather quickly
in this environment. At least one radar-indicated tornado has been
observed, and all severe hazards remain possible as the storms
approach the MS/AL border.

Convective evolution in the highlighted area remains somewhat
uncertain due to overturned air from convection earlier today.
Temperatures and dewpoints in western AL are generally a few degrees
cooler than the environment in which the storms are currently
located. This is contributing to substantially increasing MLCIN with
eastward extent through the delineated area. This could contribute
to rapidly weakening storms deeper into AL and decreasing severe
hazards later tonight. However, modest low-level advection is
anticipated which could lessen inhibition. The degree to which this
may occur in a narrow zone ahead of the ongoing supercells remains
uncertain. Should this occur, the threat for all severe hazards with
these supercells -- as well as any additional storms that develop in
northern MS -- could persist for the next few hours across western
AL. Due to this scenario, downstream WW issuance appears likely
during the next couple of hours.

..Flournoy/Grams.. 06/19/2023

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!52IgG23DKcxgwLR6Vt6if4yiX9lSbzMICF-4IvV8xChhxS1qlQprH9WlOodHIqv8hIh4P427z= LZpyY7Hs-kwN5gLjH8$ for graphic product...

ATTN...WFO...OHX...BMX...HUN...MOB...MEG...JAN...

LAT...LON 34498818 34978807 35198792 35268752 35208708 34728684
34018677 32888686 32138703 31438735 31318764 31308809
31548847 31928846 34498818=20


=3D =3D =3D
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