ACUS02 KWNS 120658
SWODY2
SPC AC 120657

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CST Tue Nov 12 2024

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER
MS VALLEY AND NORTHEAST GULF COAST...FOR COASTAL WA/OR/NORTHERN
CA...

...SUMMARY...
A marginal tornado/wind threat is apparent on Wednesday afternoon
into Wednesday night across a part of the central Gulf Coast States.
Thunderstorms with strong to locally severe gusts are also possible
near the immediate coasts of Washington, Oregon, and northern
California.

...Synopsis...
A mid/upper-level shortwave trough is forecast to move eastward from
the Great Plains toward the Midwest and OH/TN Valleys on Wednesday.
In conjunction with this shortwave trough, a weak surface low will
move from the east-central Plains toward the Great Lakes region, as
a trailing cold front moves through parts of the middle/lower MS
Valley. Farther west, a deep mid/upper-level trough will progress
farther inland across the western CONUS, as an embedded shortwave
moves across northern CA into the interior Northwest.

...Lower Mississippi Valley/Central Gulf Coast region...
Rich low-level moisture (with upper 60s to lower 70s F dewpoints) is
forecast to gradually spread northward across the lower MS Valley
region from later in the D1/Tuesday period into D2/Wednesday. Weak
lapse rates will tend to limit instability, while stronger
mid/upper-level flow will generally remain north of the richer
moisture. However, deep-layer shear will likely become at least
marginally supportive of organized storms, while some enhancement to
low-level flow/shear is forecast as the shortwave trough to the
north glances the region. This evolution could support a few
marginal supercells and/or stronger clusters during the afternoon
and evening, with a threat of locally damaging winds and possibly a
tornado or two.

Elevated storms will also be possible through the day/evening to the
north of the richer surface moisture. While effective shear will be
sufficient for a few strong elevated storms, the severe potential
with northward extent will tend to be limited by weak midlevel lapse
rates and generally marginal MUCAPE.

...WA/OR/northern CA coasts...
Cooling temperatures aloft will support weak destabilization in the
vicinity of the WA/OR/northern CA coasts through the day on
Wednesday. While convection will be rather low-topped, instability
may become sufficient (with SBCAPE potentially in the 200-500 J/kg
range) for occasional thunderstorms. The strongest low-level flow
will precede the primary destabilization, but persistent and rather
strong deep-layer southwesterly flow could support modestly
organized line segments and/or weakly rotating cells, with a threat
of isolated severe convective gusts and perhaps some small hail. A
brief tornado also cannot be ruled out, though the favored location
(if any) of any longer-lived rotating cells remains uncertain at
this time.

..Dean.. 11/12/2024

$$

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