Subj : DAY1SVR: Day 1 Convective Outlook
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Dec 18 2024 00:56:57

ACUS01 KWNS 180056
SWODY1
SPC AC 180054

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0654 PM CST Tue Dec 17 2024

Valid 180100Z - 181200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE ARK-LA-TEX AND MID MISSISSIPPI VALLEY...

....SUMMARY...
Marginally severe thunderstorms associated with isolated severe
gusts and hail will be possible from late this evening into early
Wednesday morning from parts of the Ark-La-Tex into the mid
Mississippi Valley.

....Ark-La-Tex/Mid Mississippi Valley...
A mid-level trough will move southeastward across the central U.S.
tonight, as an associated cold front advances southeastward into the
Ark-La-Tex and mid Mississippi Valley. Ahead of the front, moisture
advection will gradually increase surface dewpoints into the lower
to mid 60s F from northeast Texas to western Tennessee. In response,
destabilization will take place ahead of the front with MUCAPE
increasing into the 1000 to 1500 J/kg range. As low-level
convergence strengthens near the front late this evening, scattered
thunderstorm initiation is expected. As cell coverage increases, a
line of storms will likely develop just ahead of the front around
midnight. This line is forecast to move southeastward across the
Ark-La-Tex and mid Mississippi Valley during the overnight period.

RAP forecast soundings after midnight near the expected location of
the line in northeastern Arkansas have a temperature inversion in
the boundary layer, with instability primarily located above 700 mb.
This elevated instability combined with effective shear of 30 to 40
knots may be enough for a marginal severe threat overnight as the
low-level jet gradually strengthens. Severe gusts and hail will be
the primary threats, especially if cells can become surface-based
within the stronger low-level flow. As the line moves southeastward
across eastern Arkansas and western Tennessee late tonight into
early Wednesday morning, a brief tornado will also be possible.
However, low to mid-level lapse rates are forecast to be poor, which
will help to limit the severe weather risk.

...Broyles.. 12/18/2024

$$

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