RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1026 AM CST Thu Dec 25 2025
Valid 251630Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
COASTAL CALIFORNIA AND PORTIONS OF THE CENTRAL VALLEY...
...SUMMARY...
An isolated risk for severe gusts/localized wind damage and perhaps
a brief tornado will be possible today into this evening along much
of the California Coast and portions of the Central Valley.
...California...
Recent satellite imagery shows a mid/upper-level low over the
eastern Pacific and a negative-tilt shortwave trough moving
northward along the northern CA and OR Coast. An upstream mid-level
jet and associated vorticity maximum will move through the base of
the eastern Pacific upper low/trough and approach the San Francisco
Bay and northern CA vicinity this evening.
Strong to locally severe thunderstorms capable of producing mainly
isolated severe/damaging winds will remain possible with convection
today into this evening. Weak instability is forecast to persist
across much of coastal CA into the Central Valley, with cool surface
temperatures, saturated profiles, and modest lapse rates aloft
(reference the 12Z OAK sounding) limiting the development of greater
MUCAPE. Still, a favorable kinematic environment with enhanced
west-southwesterly mid/upper-level flow will conditionally support
occasional strong to severe convection, contingent on sufficiently
deep/sustained updraft development.
Low-level hodographs are forecast to remain enlarged enough to yield
a low risk for a brief tornado across much of the Marginal Risk
area. Consensus of latest model guidance indicates low/mid-level
flow will weaken somewhat this afternoon before gradually
re-intensifying this evening as the next embedded shortwave trough
and associated mid-level jet overspread coastal northern/central CA.
A mix of linear bands and cellular convective structures may
continue to pose an intermittent risk for isolated damaging gusts
and perhaps a brief tornado into this evening/tonight, before the
severe threat gradually diminishes towards 12Z early Friday morning.
..Gleason/Supinie.. 12/25/2025
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1117 AM CST Thu Dec 25 2025
Valid 261200Z - 271200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe storms are not expected across the continental U.S. Friday or
Friday night.
...Synopsis...
A persistent mid-level ridge will begin to weaken as it moves across
the central U.S. Friday. At the same time, a broad trough over the
West Coast will finally move onshore and into the western states.
Isolated thunderstorms will be possible during the day across
coastal California eastward into the Great Basin/Intermountain West,
as moisture associated with the trough streams inland. Weak buoyancy
and only minimal surface heating from remnant cloud cover and
multiple days of precipitation should greatly limit severe
potential.
...Eastern Great Lakes to the Mid Atlantic...
A secondary trough on the eastern periphery of the ridge will
intensify as it moves out of the Great Lakes and into the
Northeastern US late Friday into early Saturday. A modest surface
low and low-level warm advection will allow for weak elevated
destabilization and isolated storms over parts of eastern MI and OH,
into the central Appalachians Friday evening. Buoyancy will become
increasingly scant farther east into the Mid Atlantic. While a few
storms remain possible into early Saturday, peak MUCAPE below 500
J/kg suggests severe potential is very low.
..Lyons.. 12/25/2025
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