ACUS02 KWNS 090558
SWODY2
SPC AC 090557

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Tue Apr 09 2024

Valid 101200Z - 111200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN CENTRAL AND
SOUTHERN MS...EASTERN LA...AND SOUTHWEST AL...

...SUMMARY...
Numerous to widespread severe thunderstorms are probable beginning
Wednesday morning across parts of the central Gulf Coast States.
These will include potential for both many tornadoes, some of which
should be strong (EF2-EF3 caliber), and widespread damaging wind
swaths with embedded significant severe gusts.

...Synopsis...
Primary feature of interest will be a southern-stream shortwave
trough over west TX at 12Z Wednesday. This shortwave impulse should
begin to phase with a northern-stream wave digging into the Upper
Midwest, yielding a full-latitude amplified trough near the MS
Valley by 12Z Thursday. This will result in substantial flow
amplification through the troposphere, commencing by Wednesday
morning as a surface cyclone gradually deepens northeastward from
east TX towards the Lower OH Valley.

...Central Gulf Coast/Deep South...
A swath of numerous to widespread severe storms appears increasingly
likely on Wednesday morning to afternoon, highlighted within the
level 3-4/ENH-MDT risks. A nocturnal tornado/wind threat should
persist into Wednesday night across south AL, the FL Panhandle, and
southwest GA.

An MCS is expected to be ongoing from the Sabine to Lower MS Valleys
vicinity at 12Z Wednesday, with the southern portion potentially
already producing severe wind and tornadoes. Guidance is more
consistent with the indication of a plume of moderately steep
mid-level lapse rates ahead of this activity, emanating around the
MCS from the northwest Gulf. A renewed surge of rich western Gulf
moisture is progged to advect north-northeast just ahead of the
morning activity across LA, yielding moderate buoyancy across
convection-free areas of LA into south MS.

Convective intensity should diurnally increase through late
morning/midday within already strong low-/deep-layer shear. The
initial thermodynamic environment coupled with further strengthening
of tropospheric wind fields should yield potential for an intense
QLCS spreading east-northeast into the afternoon. Embedded
supercells, with a possibility for semi-discrete ones just ahead of
the line along its southern flank, in addition to small-scale bowing
segments will be conducive to tornadoes and damaging wind swaths.
Primary uncertainty is just how far north-northeast this severe MCS
will extend, as both weaker mid and low-level lapse rates with
northeast extent and deep convection regenerating southwestward
towards the larger buoyancy plume, may yield a relatively pronounced
northern cutoff to the more widespread severe threat.

A tornado and severe wind threat should linger into Wednesday
evening/night, at least along the northeast Gulf coast region, with regenerative offshore supercells moving inland. Guidance is
consistent in suggesting further increases of low-level
shear/hodograph curvature into the FL Panhandle vicinity through 12Z
Thursday, supporting a nocturnal strong tornado risk.

...Ark-La-Tex/Ark-La-Miss to the TN Valley...
A separate area of severe storms, primarily in the form of large
hail initially, should develop along a portion of the Red River
Valley near the Ark-La-Tex. This activity will be supported by a
plume of steep mid-level lapse rates near the cold-core region of
the mid-level low, and the northwest periphery of the residual Gulf
low-level moisture plume that will likely be modified by the
extensive MCS near the central Gulf Coast.

Guidance has shown more variability with timing the east and
eventual northeast pivot of the mid-level low on Wednesday night,
yielding uncertainty in how far northeast at least a low-probability
severe threat will extend. There will be an attempt at overnight
airmass recovery northward from the central Gulf Coast to the TN
Valley in the wake of the large early-day MCS. Low-level shear
profiles will be supportive of rotating storms into early Wednesday,
with lower-probability tornado/wind threats.

..Grams.. 04/09/2024

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