Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CST Thu Dec 25 2025
Valid 281200Z - 021200Z
...DISCUSSION...
A mid-level trough is forecast to move eastward across the central
U.S. on Sunday, as an associated cold front advances southeastward
into the Ozarks and mid Mississippi Valley. Near the front,
scattered thunderstorms are expected by afternoon from the
Ark-La-Tex northeastward into the lower Ohio Valley. Any severe
threat will likely remain marginal due to weak instability, and a
tendency for storms to be post-frontal.
From Monday to Thursday, the mid-level trough is forecast to
gradually move eastward across the central and eastern U.S.,
eventually reaching the western Atlantic by Thursday. In its wake, a
cool and dry airmass is forecast to overspread much of the
continental U.S., making conditions unfavorable for thunderstorms in
most areas.
Read more
Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CST Thu Dec 25 2025
Valid 281200Z - 021200Z
...DISCUSSION...
A mid-level trough is forecast to move eastward across the central
U.S. on Sunday, as an associated cold front advances southeastward
into the Ozarks and mid Mississippi Valley. Near the front,
scattered thunderstorms are expected by afternoon from the
Ark-La-Tex northeastward into the lower Ohio Valley. Any severe
threat will likely remain marginal due to weak instability, and a
tendency for storms to be post-frontal.
From Monday to Thursday, the mid-level trough is forecast to
gradually move eastward across the central and eastern U.S.,
eventually reaching the western Atlantic by Thursday. In its wake, a
cool and dry airmass is forecast to overspread much of the
continental U.S., making conditions unfavorable for thunderstorms in
most areas.
Read more
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
Read more
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
Read more
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
Read more
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
Read more
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
Read more
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1250 AM CST Thu Dec 25 2025
Valid 261200Z - 271200Z
...Synopsis...
Upper ridging will gradually shunt eastward from the Plains to the
Midwest on Friday as an upper trough impinges on the Rockies. At the
surface, lee troughing will intensify over the Plains, leading to
another day of at least modestly dry downslope flow along the High
Plains. Similar to Day 1, Elevated highlights have been introduced
for the Texas Panhandle and surrounding areas. Here, 15+ mph
sustained westerly surface winds will coincide with 20 percent RH,
atop fuels that continue to cure given dry air and longer term lack
of rainfall.
..Squitieri.. 12/25/2025
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1250 AM CST Thu Dec 25 2025
Valid 261200Z - 271200Z
...Synopsis...
Upper ridging will gradually shunt eastward from the Plains to the
Midwest on Friday as an upper trough impinges on the Rockies. At the
surface, lee troughing will intensify over the Plains, leading to
another day of at least modestly dry downslope flow along the High
Plains. Similar to Day 1, Elevated highlights have been introduced
for the Texas Panhandle and surrounding areas. Here, 15+ mph
sustained westerly surface winds will coincide with 20 percent RH,
atop fuels that continue to cure given dry air and longer term lack
of rainfall.
..Squitieri.. 12/25/2025
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1244 AM CST Thu Dec 25 2025
Valid 251200Z - 261200Z
...Synopsis...
An upper ridge will prevail over the central CONUS as a mid-level
trough over the Interior West de-amplifies, with embedded
perturbations impinging on the Rockies today. This will support the
eastward progression of a surface low over the northern Plains,
which in turn will lead to dry downslope flow along the lee of the
Rockies. By afternoon widespread 10-15 mph sustained westerly
surface winds will generally coincide with 15-25 percent RH.
Elevated highlights are in place across portions of the Texas
Panhandle and immediate surrounding areas, where the best overlap of
15+ mph winds, 15-20 percent RH, and dry fuels should occur.
..Squitieri.. 12/25/2025
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1244 AM CST Thu Dec 25 2025
Valid 251200Z - 261200Z
...Synopsis...
An upper ridge will prevail over the central CONUS as a mid-level
trough over the Interior West de-amplifies, with embedded
perturbations impinging on the Rockies today. This will support the
eastward progression of a surface low over the northern Plains,
which in turn will lead to dry downslope flow along the lee of the
Rockies. By afternoon widespread 10-15 mph sustained westerly
surface winds will generally coincide with 15-25 percent RH.
Elevated highlights are in place across portions of the Texas
Panhandle and immediate surrounding areas, where the best overlap of
15+ mph winds, 15-20 percent RH, and dry fuels should occur.
..Squitieri.. 12/25/2025
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
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
Read more
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
Read more
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0654 PM CST Wed Dec 24 2025
Valid 250100Z - 251200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ALONG MUCH OF
THE CALIFORNIA COAST AND PORTIONS OF THE CENTRAL VALLEY...
...SUMMARY...
An isolated risk for severe/damaging gusts and perhaps a brief
tornado will exist through tonight along much of the California
Coast and portions of the Central Valley.
... 01Z Update ...
Multiple bands of convection look likely this evening into the early
morning hours as a deepening surface low approaches the California
coast. The strongest convective elements within this first band,
currently approaching the San Francisco Bay area, will be capable of
producing gusty winds as it moves inland.
Wind fields will strengthen overnight in response to the approaching
low. This will maintain sufficient low-level theta-e advection to
support modest low-level instability through Christmas morning.
Numerical guidance this evening indicates a more intense band of
convection will approach the central and northern California coast
in the 08-12Z (12-4AM PT) window, quickly moving into northern
portions of the Central Valley. Given the modest instability and
strong wind fields, isolated strong wind gusts and a brief tornado
will be possible overnight, especially along the coast.
Elsewhere along the California coast, low-level moist advection will
persist through the night supporting localized convective
development. For the same reasons listed above, an isolated strong
wind gust or brief tornado would be possible with these convective
elements.
... Central Valley ...
Thunderstorms have developed this afternoon across portions of the
Central Valley near Sacramento. Surface-based instability around 500
J/kg within a strongly sheared environment will support an isolated
wind threat. Should convective elements become more cellular, the
low-level wind fields would support a brief tornado, especially in
areas where surface-based instability can be realized. This activity
will lift generally northward across the Central Valley through this
evening.
..Marsh.. 12/25/2025
Read more
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0333 PM CST Wed Dec 24 2025
Valid 261200Z - 011200Z
...Synopsis...
Fire weather concerns will continue through the weekend across the
southern High Plains as the mid-level trough shifts into the
central/northern Plains by Day 5/Sunday. Increasing mid-level
westerly flow along with lee troughing across the Plains will
support a dry downslope regime for the TX Panhandle and vicinity on
Days 3-4/Friday-Saturday, followed by a strong cold front moving
through the central and eastern U.S. early next week. Upper-level
ridging will likely return to the West while deep layer northwest
flow under a troughing regime sets up across the eastern CONUS for
the middle of next week.
...Days 3-4/Friday-Saturday - Southern/Central High Plains...
Dry conditions and anomalously warm temperatures under a broad
upper-level ridge combined with downslope enhanced westerly winds, a
dry boundary layer and dry fuels should support an ongoing fire
weather threat to far eastern NM, TX Panhandle and portions of
western OK Friday and Saturday. As such, 40% critical probabilities
were maintained for both Friday and Saturday. Increasing mid-level
flow over central Rockies could present a more localized downslope
wind event along the CO Front Range and leeward of the Sangre de
Cristo Mountains Friday and Saturday.
...Day 5-8/Sunday-Wednesday...
Primary fire weather focus will shift to a strong cold front moving
into the central and Southern Plains on Day 5/Sunday, reaching the
Gulf Coast by Day 6/Monday. However, ample cloud cover and some
precipitation along and behind the front could limit fire weather
impacts early next week particularly east of the I-35 corridor in
the Southern Plains. In addition, some uncertainty in frontal timing
precludes introduction of critical probabilities at this time. Dry,
post-frontal flow could also bring a brief fire weather concern to
portions of the Southeast Monday and even FL Tuesday where minimal
rainfall is expected.
..Williams.. 12/24/2025
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0333 PM CST Wed Dec 24 2025
Valid 261200Z - 011200Z
...Synopsis...
Fire weather concerns will continue through the weekend across the
southern High Plains as the mid-level trough shifts into the
central/northern Plains by Day 5/Sunday. Increasing mid-level
westerly flow along with lee troughing across the Plains will
support a dry downslope regime for the TX Panhandle and vicinity on
Days 3-4/Friday-Saturday, followed by a strong cold front moving
through the central and eastern U.S. early next week. Upper-level
ridging will likely return to the West while deep layer northwest
flow under a troughing regime sets up across the eastern CONUS for
the middle of next week.
...Days 3-4/Friday-Saturday - Southern/Central High Plains...
Dry conditions and anomalously warm temperatures under a broad
upper-level ridge combined with downslope enhanced westerly winds, a
dry boundary layer and dry fuels should support an ongoing fire
weather threat to far eastern NM, TX Panhandle and portions of
western OK Friday and Saturday. As such, 40% critical probabilities
were maintained for both Friday and Saturday. Increasing mid-level
flow over central Rockies could present a more localized downslope
wind event along the CO Front Range and leeward of the Sangre de
Cristo Mountains Friday and Saturday.
...Day 5-8/Sunday-Wednesday...
Primary fire weather focus will shift to a strong cold front moving
into the central and Southern Plains on Day 5/Sunday, reaching the
Gulf Coast by Day 6/Monday. However, ample cloud cover and some
precipitation along and behind the front could limit fire weather
impacts early next week particularly east of the I-35 corridor in
the Southern Plains. In addition, some uncertainty in frontal timing
precludes introduction of critical probabilities at this time. Dry,
post-frontal flow could also bring a brief fire weather concern to
portions of the Southeast Monday and even FL Tuesday where minimal
rainfall is expected.
..Williams.. 12/24/2025
...Please see www.spc.noaa.gov/fire for graphic product...
Read more
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0150 PM CST Wed Dec 24 2025
Valid 242000Z - 251200Z
...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/damaging gusts and perhaps a brief
tornado will exist today into tonight along much of the California
Coast and portions of the Central Valley.
...20Z Update...
...Central/Northern California...
Water vapor imagery shows the shortwave trough already moving
inland. In the wake of this activity, visible satellite shows
potential for cloud cover to reduce within the Central Valley from
west to east. Some forecast soundings show destabilization is
possible by late afternoon. Given the southeast flow within the
Valley and strong flow aloft, a conditional threat for a marginal
supercell/brief tornado could develop.
Greater confidence exists with activity later in the evening into
Thursday morning associated with a secondary, stronger shortwave
trough. Another narrow band of convection is expected ahead of this
shortwave and will impact parts of the central/northern California
Coast and eventually parts of the Central Valley as well. Isolated
damaging winds and a brief tornado would be possible with this
activity.
...Southern California...
A spatially limited threat for wind damage and a brief tornado will
exist for another few hours this afternoon. A low-topped band of
convection recently moved through much of the LA Basin and will
generally continue eastward. There may be a narrow sliver of
dewpoints near 60 F just east of this activity. Dewpoints closer to
San Diego are only in the upper 50s F, however. Strong wind shear at
low levels will maintain this marginal risk, though decreasing
buoyancy southward and inland should lead to a downward trend in
intensity.
..Wendt.. 12/24/2025
.PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 24 2025/
...California...
A shallow band of pre-frontal convection may continue to pose a
threat for locally severe/damaging winds (especially across higher
terrain/ridgetops) and perhaps a brief tornado this morning across
parts of coastal southern CA. This activity is being supported by
strong low-level warm advection and large-scale ascent associated
with an enhanced mid/upper-level jet. Current expectations are for
this activity to continue moving eastward through the afternoon
across the remainder of coastal southern CA in a strongly sheared
environment. However, various NAM/RAP forecast soundings across this
area suggest that even with low 60s surface dewpoints and
modest/filtered daytime heating, the overall severe threat will
likely remain isolated due to poor lapse rates aloft and limited
boundary-layer instability. Reference Mesoscale Discussion 2269 for
more details on the near-term severe threat across southern CA.
Additional rounds of convection are expected later this evening and
overnight into early Thursday morning over portions of
northern/central CA, as multiple mid-level shortwave troughs
embedded within persistent large-scale upper troughing over the
eastern Pacific overspread these areas. One such shortwave trough is
forecast to advance over coastal central CA and vicinity around
25/00-06Z this evening, with cool temperatures aloft (less than -20C
at 500 mb) supporting weak MUCAPE. Both low-level and deep-layer
shear are expected to gradually increase this evening as the
shortwave trough approaches, with some updraft organization
possible. Strong to locally severe winds and a brief tornado or two
appear possible with this activity, but uncertainty is still
substantial whether sufficient instability will be present to
support surface-based thunderstorms.
A stronger mid-level shortwave trough will move east-northeastward
from the eastern Pacific and approach the northern CA Coast by 12Z
Thursday morning, along with a deepening surface low and attendant
cold front. A 70-80+ kt mid-level jet will accompany this shortwave
trough, along with a 50-60 kt south-southwesterly low-level jet. A
broken band of low-topped thunderstorms will likely develop in
association with this shortwave trough along/ahead of the front, and
overspread coastal portions of northern/central CA late tonight
through early Thursday morning (25/06-12Z). A strongly sheared
environment and weak but sufficient MLCAPE may exist to support at
least an isolated threat for severe/damaging winds and a tornado or
two as this activity spreads inland through the end of the period.
Still, the overall severe threat should be tempered by the lack of
stronger instability.
Finally, some chance for low-topped/mini supercells may exist late
this afternoon/evening across parts of the Central Valley of CA. If
these thunderstorms can develop and be sustained, they could pose a
threat for both damaging winds and a brief tornado. But, confidence
in this scenario occurring remains rather low.
Read more
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0150 PM CST Wed Dec 24 2025
Valid 242000Z - 251200Z
...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/damaging gusts and perhaps a brief
tornado will exist today into tonight along much of the California
Coast and portions of the Central Valley.
...20Z Update...
...Central/Northern California...
Water vapor imagery shows the shortwave trough already moving
inland. In the wake of this activity, visible satellite shows
potential for cloud cover to reduce within the Central Valley from
west to east. Some forecast soundings show destabilization is
possible by late afternoon. Given the southeast flow within the
Valley and strong flow aloft, a conditional threat for a marginal
supercell/brief tornado could develop.
Greater confidence exists with activity later in the evening into
Thursday morning associated with a secondary, stronger shortwave
trough. Another narrow band of convection is expected ahead of this
shortwave and will impact parts of the central/northern California
Coast and eventually parts of the Central Valley as well. Isolated
damaging winds and a brief tornado would be possible with this
activity.
...Southern California...
A spatially limited threat for wind damage and a brief tornado will
exist for another few hours this afternoon. A low-topped band of
convection recently moved through much of the LA Basin and will
generally continue eastward. There may be a narrow sliver of
dewpoints near 60 F just east of this activity. Dewpoints closer to
San Diego are only in the upper 50s F, however. Strong wind shear at
low levels will maintain this marginal risk, though decreasing
buoyancy southward and inland should lead to a downward trend in
intensity.
..Wendt.. 12/24/2025
.PREV DISCUSSION... /ISSUED 1025 AM CST Wed Dec 24 2025/
...California...
A shallow band of pre-frontal convection may continue to pose a
threat for locally severe/damaging winds (especially across higher
terrain/ridgetops) and perhaps a brief tornado this morning across
parts of coastal southern CA. This activity is being supported by
strong low-level warm advection and large-scale ascent associated
with an enhanced mid/upper-level jet. Current expectations are for
this activity to continue moving eastward through the afternoon
across the remainder of coastal southern CA in a strongly sheared
environment. However, various NAM/RAP forecast soundings across this
area suggest that even with low 60s surface dewpoints and
modest/filtered daytime heating, the overall severe threat will
likely remain isolated due to poor lapse rates aloft and limited
boundary-layer instability. Reference Mesoscale Discussion 2269 for
more details on the near-term severe threat across southern CA.
Additional rounds of convection are expected later this evening and
overnight into early Thursday morning over portions of
northern/central CA, as multiple mid-level shortwave troughs
embedded within persistent large-scale upper troughing over the
eastern Pacific overspread these areas. One such shortwave trough is
forecast to advance over coastal central CA and vicinity around
25/00-06Z this evening, with cool temperatures aloft (less than -20C
at 500 mb) supporting weak MUCAPE. Both low-level and deep-layer
shear are expected to gradually increase this evening as the
shortwave trough approaches, with some updraft organization
possible. Strong to locally severe winds and a brief tornado or two
appear possible with this activity, but uncertainty is still
substantial whether sufficient instability will be present to
support surface-based thunderstorms.
A stronger mid-level shortwave trough will move east-northeastward
from the eastern Pacific and approach the northern CA Coast by 12Z
Thursday morning, along with a deepening surface low and attendant
cold front. A 70-80+ kt mid-level jet will accompany this shortwave
trough, along with a 50-60 kt south-southwesterly low-level jet. A
broken band of low-topped thunderstorms will likely develop in
association with this shortwave trough along/ahead of the front, and
overspread coastal portions of northern/central CA late tonight
through early Thursday morning (25/06-12Z). A strongly sheared
environment and weak but sufficient MLCAPE may exist to support at
least an isolated threat for severe/damaging winds and a tornado or
two as this activity spreads inland through the end of the period.
Still, the overall severe threat should be tempered by the lack of
stronger instability.
Finally, some chance for low-topped/mini supercells may exist late
this afternoon/evening across parts of the Central Valley of CA. If
these thunderstorms can develop and be sustained, they could pose a
threat for both damaging winds and a brief tornado. But, confidence
in this scenario occurring remains rather low.
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