Day 1 Severe Weather Outlook

Valid 291630Z – 301200Z

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEASTERN
LOUISIANA AND CENTRAL MISSISSIPPI TO NORTHWESTERN ALABAMA AND MIDDLE
TENNESSEE…

…SUMMARY…
A few severe thunderstorms are possible this afternoon and evening
across parts of Mississippi, northwest Alabama, and western/middle
Tennessee. Damaging winds and isolated tornadoes are the main
risks.

…Lower MS Valley into TN Valley…
Morning water vapor loop shows a vigorous shortwave trough rotating
across west central TX. Strong large-scale ascent ahead of this
feature is resulting in scattered thunderstorm activity over the
upper TX coast and parts of LA. A surface baroclinic zone extends
from this area northeastward into middle TN. 12z model guidance
continues to forecast the development of a mesolow along the
boundary, tracking from MS into TN during the afternoon and evening.
Vertical shear profiles will strengthen considerably in vicinity of
the low, resulting in a very favorable kinematic environment for
supercells and bowing structures capable of damaging winds and
tornadoes. The primary limiting factor is weak instability, with
MLCAPE generally expected to be in the 200-700 J/kg range. While
the low CAPE scenario limits confidence in a more widespread severe
event, the strength of the shear profiles and the favorable
mesoscale setup suggests some risk of a small corridor of greater
threat from northeast MS into southern middle TN during the 21-03z
time frame.

..Hart/Dean.. 12/29/2019

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