ACUS03 KWNS 011930
SWODY3
SPC AC 011929
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0129 PM CST Thu Jan 01 2026
Valid 031200Z - 041200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHEAST...AND ALSO FROM PARTS OF NORTHERN CA INTO COASTAL
SOUTHWEST OR...
...SUMMARY...
Isolated severe storms are possible across parts of the Southeast on
Saturday, and the Sacramento and northern San Joaquin Valleys to
coastal northern California-southwest Oregon during the late
afternoon to evening.
...Parts of the Southeast...
A positive-tilt mid/upper-level shortwave trough is forecast to move
from the lower MS Valley toward the South Atlantic Coast through the
period, as an attendant surface low moves from parts of AL/GA to
offshore of SC by late evening. A trailing cold front will move
through parts of the Southeast and central Gulf Coast vicinity.
Guidance continues to vary regarding the timing of the front and
extent of heating/destabilization across the warm sector, but a
plume of weak to moderate MLCAPE is expected to be in place
along/ahead of the cold front during the afternoon, as low-level
moisture spreads northeastward. Some veering/weakening of low-level
flow is forecast across parts of the warm sector with time
(especially with southwestward extent), but increasing midlevel flow
will result in sufficient effective shear for organized storms,
including some supercell potential.
Any lingering morning convection may intensify during the afternoon,
with additional storm development expected along/ahead of the cold
front, and near the primary buoyancy gradient and effective warm
front. This activity could pose at least a low-probability threat
for all severe hazards. A corridor of somewhat greater potential may
evolve within the broader Marginal Risk area, though uncertainty
remains regarding the magnitude of diurnal heating/destabilization,
and the strength/timing of the primary shortwave trough as it moves
quickly eastward.
...Northern CA to coastal southwest OR...
Latest guidance still depicts potential for multiple shortwave
troughs to eject northeastward from a deep mid/upper-level trough
off of the Pacific Coast. The southernmost shortwave is forecast to
move across central CA through the afternoon, while the more
vigorous northern shortwave is expected to affect coastal OR from
late afternoon into the evening.
The southern shortwave will be favorably timed for diurnal
convective development across the Sacramento and northern San
Joaquin Valleys, where cooling midlevel temperatures (dropping below
-20C at 500 mb) may support SBCAPE of 250-500 J/kg during the
afternoon. With relatively elongated hodographs, this generally
meager buoyancy may be sufficient for transient rotating cells to
develop, which could pose a threat for a brief tornado, small hail,
and locally gusty winds.
The northern shortwave will be accompanied by a renewed
strengthening of low-level flow, potentially increasing to
near/above 60 kt at 850 mb over the ocean and along the northern
CA/southwest OR coast. Buoyancy will remain meager, but cold
temperatures aloft will support low-topped convection that could
contribute to severe-gust potential. Transient rotating cells may
also develop offshore and approach the coast.
..Dean.. 01/01/2026
$$
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