No watches are valid as of Thu Dec 25 08:18:01 UTC 2025.MD 2270 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF THE NORTH COAST OF CALIFORNIA
Mesoscale Discussion 2270
NWS Storm Prediction Center Norman OK
0146 AM CST Thu Dec 25 2025
Areas affected...Parts of the North Coast of California
Concerning...Severe potential...Watch unlikely
Valid 250746Z - 251015Z
Probability of Watch Issuance...20 percent
SUMMARY...The risk for damaging convective gusts and possibly a
brief tornado is increasing, with the greatest threat expected
between 09-12Z.
DISCUSSION...As of 0730Z, radar data from KMUX shows an expansive,
strongly forced band of stratiform rain with gradually
deepening/intensifying convective elements. As a robust
negative-tilt shortwave trough and accompanying jet continue toward
the coast, this activity will spread east-northeastward into the
North Coast of California during the 09-12Z time frame. Despite
limited buoyancy, the strong forcing for ascent and strengthening
deep-layer flow/shear should favor a modest uptick in convective
organization/intensity as it approaches the coast. Given the
strongly forced nature and 50+ kt flow in the lowest 1 km AGL, the
primary concern will be damaging wind gusts. However, a brief
tornado cannot be ruled out, aided by upwards of 200 m2/s2 0-1 km
SRH and at least neutral boundary-layer static stability along the
immediate coastal areas.
..Weinman/Smith.. 12/25/2025
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...STO...MTR...EKA...
LAT...LON 36862224 37742283 38562351 39312403 39912430 40352457
40682447 40782431 40702392 40392355 40002312 39372247
38552192 37162146 36682149 36502170 36432200 36862224
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1137 PM CST Wed Dec 24 2025
Valid 251200Z - 261200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR MUCH OF THE
CALIFORNIA COAST AND PORTIONS OF THE CENTRAL VALLEY...
...SUMMARY...
Thunderstorms with potential to produce marginally severe wind gusts
and perhaps a brief tornado will be possible on Thursday along much
of the California Coast and portions of the Central Valley.
... Synopsis ...
A highly amplified pattern will persist across the US as a deep
trough over the eastern Pacific is maintained and a ridge builds
over the central US. A series of embedded shortwave troughs within
the eastern Pacific trough will impact the West Coast on Christmas
and Christmas night.
... California ...
The first of these shortwave troughs will be moving across the
region at the start of the forecast period, bringing with it a band
of strongly forced convection, likely located across portions of the
central coast of California into the Central Valley. As the
shortwave trough takes on an increasingly negative tilt, a 50-60
knot southerly low-level jet will be maintained allowing for
sufficient low-level theta-e advection to support a modest 100-300
J/kg of surface-based CAPE. As the convective band interacts with
this strong low-level kinematic field, gusty/damaging convective
winds may be realized at the surface, particularly with the stronger
convective elements. Forecast low-level hodographs ahead of this
convective line feature sufficient low-level curvature to support a
brief tornado should any convective element realize true
surface-based buoyancy. As the morning progresses, the
aforementioned shortwave trough will lift north then northwest
within the broader cyclonic flow across the eastern Pacific whereas
the band of convection slowly advances south and east. By midday,
the low-level wind fields should weaken sufficiently in response to
the departing shortwave trough to reduce the potential of damaging
winds/tornadoes across far southern California.
By mid-afternoon, another shortwave trough will approach the central
and northern California coast. In response, the low-level wind
fields will once again strengthen, albeit perhaps not to the extent
as with the morning wave. Another band or bands of strongly forced
convection are expected to develop across the eastern Pacific and
approach coastal areas of central California after 00Z (4 PM PT). As
was the case with the morning convection, the strongest convective
elements may be capable of mixing down the stronger winds aloft
resulting in the potential for isolated strong thunderstorm winds.
..Marsh/Squitieri.. 12/25/2025
SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 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 mid-level ridge will move across the central U.S. on Friday, as a
trough moves into the western states. Isolated thunderstorms will be
possible during the day from near the trough in central California
eastward into southwest Nevada. Additional thunderstorms will be
possible in the afternoon across parts of the Intermountain West as
surface temperatures warm. A third area with thunderstorm potential
will develop in parts of the central Appalachians as a shortwave
trough moves southeastward across the region. No severe threat is
expected over the continental U.S. on Friday or Friday night.
..Broyles.. 12/25/2025
SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0215 AM CST Thu Dec 25 2025
Valid 271200Z - 281200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
No severe threat is forecast across the U.S. on Saturday or Saturday
night.
...DISCUSSION...
A mid-level ridge will move eastward across the mid Mississippi and
Ohio Valleys on Saturday, as a trough moves through the
Intermountain West. Thunderstorms will be possible, mainly Saturday
night within anticyclonic southwesterly mid-level flow from the
southern Plains to the lower Ohio Valley. Additional storms may form
along the lower to middle Texas coast.
..Broyles.. 12/25/2025
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