Subj : DAY2 ENHANCED RISK MSVAL
To   : All
From : Dumas Walker
Date : Fri Dec 27 2024 09:17 am

ACUS02 KWNS 270720
SWODY2
SPC AC 270719

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0119 AM CST Fri Dec 27 2024

Valid 281200Z - 291200Z

....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
LOWER MISSISSIPPI VALLEY...

....SUMMARY...
An active severe-weather day is expected Saturday into Saturday
night, with severe storms likely from east Texas across the Lower
Mississippi Valley into parts of the Tennessee Valley. Large hail,
damaging winds, and tornadoes are likely, potentially including a
few strong (EF2+) tornadoes.

....East Texas/Lower Mississippi Valley to Tennessee Valley...
A southern-stream shortwave trough is likely to overspread the
southern Plains east-northeastward to the Ozarks/Mid-South Saturday
and Saturday night, with a notable and concerning strengthening of
winds aloft into late Saturday afternoon and Saturday night. This is
highlighted by global guidance depictions of increasingly strong
(50+ kt) west-southwesterly winds in the lowest 2-3 km AGL.

Scattered early day convection and residual cloud cover remain
potential complicating factors as far as forecast details,
particularly regarding the northern extent of the primary
surface-based severe risk later Saturday afternoon into Saturday
night. There are also continues to be some longitudinal uncertainty
as far as the initial severe risk across East Texas and the ArkLaTex
vicinity during the day, although Slight Risk-caliber severe
probabilities have been expanded westward with this update.

Even with these forecast uncertainties, ample mass response related
to the approaching/ejection of the mid/upper-level trough, and a
related steepening of mid-level lapse rates and strengthening
deep-layer flow fields, should result in a steady uptick of
potentially severe convection into Saturday night. This should
initially occur across East Texas toward the ArkLaMiss vicinity,
where middle 60s F surface dewpoints will become more common to the
south of a warm front shifting northward across the Mid-South.

With strengthening deep-layer shear/forcing for ascent through the
day, it appears that all severe-weather modes and hazards will
regionally occur, including semi-discrete supercells and linearly
organized bowing segments. This includes the potential for large
hail, mostly with initial development during the day, as well as
damaging winds and tornadoes, some of which could be strong (EF2+)
as 0-1 km SRH increases to 200-400 m2/s2 into mid/late Saturday
afternoon and Saturday night.

At least some damaging wind/tornado threat will probably continue
through late Saturday night/early Sunday, including parts of
Alabama/Florida Panhandle, and potentially northward into the
Cumberland plateau vicinity. This risk will exist even with minimal
buoyancy, in the presence of a robust deep-layer/low-level shear
environment highlighted by a 50-65 kt low-level jet.

...Guyer.. 12/27/2024

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