ACUS11 KWNS 260341
SWOMCD
SPC MCD 260340=20
ALZ000-MSZ000-260615-
Mesoscale Discussion 0344
NWS Storm Prediction Center Norman OK
1040 PM CDT Sat Mar 25 2023
Areas affected...parts of southern into central Alabama
Concerning...Severe potential...Watch possible=20
Valid 260340Z - 260615Z
Probability of Watch Issuance...40 percent
SUMMARY...Rapid, sustained strong thunderstorm development
accompanied by increasing severe weather potential, mainly in the
form of hail which could become sizable, appears possible overnight.
This could commence as early as 1-3 AM CDT, and a severe weather
watch may be needed.
DISCUSSION...Low-level flow is backing from westerly/southwesterly
to more of a southerly component and modestly strengthening across
the north central Gulf coast vicinity. This is allowing for
boundary-layer moisture return across the coastal plain from
southeastern Louisiana through southern Alabama, where deepening
convection has been evident along the low-level confluence zone near
the leading edge of this regime since prior to sunset. This is
occurring beneath steep lapse rates associated with daytime
boundary-layer heating and deep mixing, which occurred to the south
of a stalling frontal zone across northern portions of the Gulf
Coast states into the Great Plains.
Destabilization associated with the moistening recently became
sufficient to support short-lived thunderstorm development west of
Montgomery, AL. However, large-scale forcing for ascent remains
weak and, based on model forecast soundings, ongoing mid-level warm
advection may maintain substantial inhibition tending to suppress
sustained thunderstorm initiation for at least several more hours.
With time though, as mid/upper 60s F dew points begin to underrun
the northern periphery of the more strongly capping warmer air
aloft, initially scattered sustained thunderstorm development
appears increasingly probable. Once this occurs, intensification
may be rapid with mixed-layer CAPE forecast to increase in excess of
2000 J/kg. In the presence of strong deep-layer shear, beneath 50+
kt west-southwesterly 500 mb flow, the environment may become
conducive to supercells capable of producing sizable hail. While
low-level hodographs probably will remain modest to weak, stronger
storms may pose at least some risk for producing a tornado, in
addition to locally strong surface gusts.
Given the subtle nature of the mid/upper support, within flow that
may only very gradually transition from broadly anticyclonic to
cyclonic overnight, the timing of the more sustained, increasing
storm development remains unclear. Various model output has
suggested that this could commence as early as 06-08Z, but seems to
be trending toward a bit later overnight.
..Kerr/Thompson.. 03/26/2023
...Please see
https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-9Sq2f1Ahq6h6A8A11XD8-qMEzE4i3CZhaMe0P4AJ02RjWvsPSmWa2NsrCRFGo9Wghek8vi2O= W2tnlJG_geesDyR-GA$ for graphic product...
ATTN...WFO...BMX...MOB...JAN...LIX...
LAT...LON 31428832 31118937 31239033 32138904 32448799 32748669
33008534 32398503 32238567 31798697 31428832=20
=3D =3D =3D
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