Day 1 Severe Weather Outlook

Valid 301200Z – 311200Z

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM LOUISIANA
NORTHEASTWARD INTO TENNESSEE…

…SUMMARY…
A few strong to severe thunderstorms are possible during the day
across the northern Gulf Coast states, with a threat evolving
overnight into parts of Tennessee. Localized wind damage or a brief
tornado will be possible.

…Synopsis and Discussion…
A large, positive-tilt upper trough will deepen as it moves east
across the Plains, with a midlevel jet max strengthening to over 100
kt into MO by 12Z Thursday. At the surface, low pressure will
translate from LA northeastward into the OH Valley during the day,
with a cold front trailing southwest into the western Gulf of
Mexico. Ahead of the cold front, upper 60s to lower 70s F dewpoints
will expand north across the central Gulf Coast states, mainly south
of the TN state line.

Storms are likely to be ongoing Wednesday morning across northern
MS, AL, and TN in a zone of low-level warm advection. These storms
are not expected to be severe as the surface air mass will be cool
relative to temperatures aloft. Later in the day, modest southerly
winds will support theta-e advection, with MLCAPE of 500-750 J/kg
likely developing over LA, MS and AL. Scattered storms due to ample
moisture and minimal CIN should support a few cluster of
thunderstorms during the afternoon. Veering winds with height
suggest cells capable of locally damaging wind, or perhaps a brief,
weak tornado, but low-level lapse rates will hamper severe potential
overall.

Isolated severe storms may develop during the evening and overnight
along the cold front over MS, and into parts of TN and perhaps
northern GA. By late Wednesday night, 850 mb winds will likely be
stronger than during the day ahead of the advancing cold front, with
localized wind damage or a brief/weak tornado possible where surface
based instability exists.

Farther west into TX, elevated instability will exist well behind
the surface front which will support at least isolated storms along
coastal areas. Marginal deep-layer shear in the cloud-bearing layer
as well as poor lapse rates aloft suggest severe hail is unlikely.

..Jewell/Bentley.. 10/30/2019

$$

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