RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1010 AM CST Fri Nov 14 2025
Valid 141630Z - 151200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms may impact parts of southern California late
tonight into early Saturday morning, but organized severe
thunderstorms are not expected.
...Discussion...
Within prevalent split upper flow over western North America, a
southern-stream closed low off the coast of California will slowly
approach with the parent trough taking on a more neutral/slight
negative tilt over time. Showers/some thunderstorms will increase
toward the coast late tonight through early Saturday with the
approach of a frontal band. Instability is forecast to remain very
weak, with poor lapse rates aloft. Nevertheless, low-topped
convection may occasionally reach levels sufficient for charge
separation and lightning flashes as it approaches the coast and
moves onshore across parts of southern California late tonight and
early Saturday. Low-level winds are expected to remain modest, but
south-southwesterly flow will strengthen with height through
mid/upper levels. While strong/gusty winds may occur in the higher
terrain, the overall severe threat should be limited by minimal
instability and weak low-level shear.
..Guyer/Smith.. 11/14/2025
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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0156 PM CST Fri Nov 14 2025
Valid 142000Z - 151200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Isolated thunderstorms may impact parts of southern California late
tonight into early Saturday morning, but organized severe
thunderstorms are not expected.
...20z Update...
No changes were made to the prior valid outlook. Isolated
thunderstorms remain possible over parts of southern CA this evening
and into early Saturday. Severe weather is unlikely given the very
weak buoyancy and shallow nature of convection. See the previous
discussion for more information.
..Lyons.. 11/14/2025
.PREV DISCUSSION... /ISSUED 1010 AM CST Fri Nov 14 2025/
...Discussion...
Within prevalent split upper flow over western North America, a
southern-stream closed low off the coast of California will slowly
approach with the parent trough taking on a more neutral/slight
negative tilt over time. Showers/some thunderstorms will increase
toward the coast late tonight through early Saturday with the
approach of a frontal band. Instability is forecast to remain very
weak, with poor lapse rates aloft. Nevertheless, low-topped
convection may occasionally reach levels sufficient for charge
separation and lightning flashes as it approaches the coast and
moves onshore across parts of southern California late tonight and
early Saturday. Low-level winds are expected to remain modest, but
south-southwesterly flow will strengthen with height through
mid/upper levels. While strong/gusty winds may occur in the higher
terrain, the overall severe threat should be limited by minimal
instability and weak low-level shear.
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1110 AM CST Fri Nov 14 2025
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE SATURDAY
AFTERNOON AND EVENING ACROSS PARTS OF EASTERN OHIO...WESTERN
PENNSYLVANIA AND NORTHERN WEST VIRGINIA...
...SUMMARY...
Showers and a few thunderstorms may be accompanied by strong wind
gusts across parts of the upper Ohio Valley late Saturday afternoon
through Saturday evening.
...Discussion...
Although smaller-scale developments remain uncertain, latest model
output offers little change to prior runs concerning the large-scale
pattern evolution Saturday through Saturday night. It still appears
that a more progressive flow emanating from the northern
mid-latitude Pacific, including a prominent cyclone on its leading
edge, will begin to impinge on a blocked regime which has evolved
across parts of eastern North America into the Atlantic. The
cyclone is likely to undergo considerable deformation and weaken,
but an emerging mid-level perturbation is forecast to dig across the
upper through lower Great Lakes region, accompanied by secondary
surface cyclogenesis.
Upstream, the westerlies may undergo notable amplification,
including building ridging across and east of the Canadian and
northern U.S. Rockies, as well as across parts of the central into
eastern northern mid-latitude Pacific. In between the ridge axes,
models indicate that splitting troughing will progress across the
eastern mid-latitude Pacific. With the approach of the digging
southern portion of this trough, an initially cut-off low offshore
of the southern California/northern Baja coast is forecast to
accelerate into the Southwest late Saturday through Saturday night.
...Upper Ohio Valley...
Within the warm sector of the developing surface low, modest
low-level moisture return is forecast. Both NAM and Rapid Refresh
forecast soundings indicate that this will contribute to the
development of thermodynamic profiles characterized by at least weak
conditional and convective instability in the lowest 5-6 km AGL,
becoming focused ahead of a southward advancing cold front, across
parts of the mid into upper Ohio Valley/Allegheny Plateau vicinity
by late Saturday afternoon.
Where the weak boundary-layer destabilization occurs, it appears
that a warm layer aloft may tend to suppress thunderstorm
development, and mid/upper forcing for ascent to overcome the
inhibition remains unclear due to model spread. However, there does
appear a general consensus for a pocket of modest mid-level cooling
across eastern Ohio into the western slopes of the Allegheny
Mountains late Saturday afternoon into Saturday evening. This may
be accompanied by the development of a relatively compact band of
stronger showers and thunderstorms, in the presence of strengthening
lower/mid-tropospheric wind fields (including 40-50 kt mean
west-northwesterly flow). Perhaps aided by latent cooling in
downdrafts associated with melting small hail, this activity may
contribute to the downward transfer of stronger winds to the
surface, before weakening will crossing the Allegheny Mountains
Saturday evening.
...Southwest...
It still appears that a pocket of colder mid-level air,
characterized by 500 mb temperatures as cold as near or just below
-20 C, will finally spread inland late Saturday through Saturday
night. These temperatures are generally on the warmer side compared
to cool season environments typically conducive to low-topped
convective capable of producing lightning across and inland of
Pacific coastal areas. However, it is possible that low-level
moisture return emanating from the lower latitude eastern Pacific
and Gulf of California may compensate and contribute to
thermodynamic profiles at least minimally sufficient for
thunderstorms. Even if this occurs, particularly near southern
California coastal areas, generally saturated profiles with very
weak CAPE, and low-level hodographs becoming modest to weak, seem
likely to minimize the risk for severe weather.
Otherwise, it might not be out of the question that preceding
elevated moisture return contributes to layers of weak conditional
instability minimally supportive of convection capable of producing
lightning across parts of the Mojave Desert/lower Colorado Valley
vicinity.
..Kerr.. 11/14/2025
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0122 PM CST Fri Nov 14 2025
Valid 161200Z - 171200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Scattered thunderstorm activity is possible across parts of the
lower Colorado Valley into Colorado Plateau and portions of the
central Great Plains, but the risk for severe storms still appears
negligible Sunday through Sunday night.
...Discussion...
Models indicate that significant surface cyclogenesis will proceed
Sunday through Sunday night, mainly from coastal Maine through the
Canadian Maritimes, as an associated short wave trough digs
southeast of the lower Great Lakes region and reinforces positively
tilted large-scale mid/upper troughing across much of eastern Canada
and the Northeast into adjacent western Atlantic. In the wake of
the cyclone, a cold front appears likely to advance southeast of the
northern Mid Atlantic and Ohio Valley, offshore of the Atlantic
Seaboard through the Carolinas into the Gulf Coast states by late
Sunday night.
Upstream, splitting troughing, within a broad area of generally
higher mid/upper heights, is forecast to continue to approach the
U.S Pacific coast, with perhaps the digging southern perturbation
supporting modest cyclogenesis offshore of the central California
coast Sunday night. It appears that this will contribute to the
continued east-northeastward acceleration of the remnants of an
initially cut-off low, northeast of the lower Colorado Valley
through the Rockies.
Modest deepening of lee surface troughing will probably be
accompanied by strengthening southerly low-level flow across the
high plains, but it appears that better boundary-layer moistening
off the Gulf Basin will be confined beneath a relatively warm and
capping lower/mid-tropospheric environment across the northwestern
Gulf coast into southern Great Plains.
...Southwest into Great Plains...
Cooling mid-levels, preceded by low-level moisture return from the
lower latitudes of the eastern Pacific and Gulf of California, may
contribute to thermodynamic profiles conducive to scattered
convective development capable of producing lightning across parts
of the Southwest through southern Rockies Sunday into Sunday night.
It is possible that this could include modest boundary layer
destabilization during the day across the deserts of southwestern
into central Arizona, in the presence of at least strong deep-layer
shear. A couple of thunderstorms with potential to produce hail and
surface gusts approaching or exceeding severe limits might not be
completely out of the question. While probabilities for this still
generally appear negligible, it is possible that this could change
with diminishing model spread in later outlooks for this period.
Otherwise, as mid/upper forcing for ascent increases downstream of
the Colorado Rockies by late Sunday night, an elevated moistening
layer rooted near or above 700 mb might destabilize sufficiently to
support weak convection capable of producing lightning.
..Kerr.. 11/14/2025
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