RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Mon Sep 15 19:32:02 UTC 2025.
No Mesoscale Discussions are in effect as of Mon Sep 15 19:32:02 UTC 2025.
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1132 AM CDT Mon Sep 15 2025
Valid 151630Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN HIGH PLAINS...NORTHERN MINNESOTA...OZARKS/MID-SOUTH...AND
COASTAL NC/VA...
...SUMMARY...
Isolated severe wind gusts are possible across Wyoming into western
South Dakota this afternoon to early evening, as well as portions of
the Ozarks/Mid-South. Isolated severe hail and damaging winds are
possible across far northern Minnesota in the early to
mid-afternoon. A brief tornado is possible in the northeast North
Carolina vicinity in the early morning Tuesday.
...Wyoming to Black Hills vicinity...
A shortwave trough over western Idaho will move east across
Wyoming/western South Dakota during the day, as several embedded
vorticity maxima contribute regions of enhanced ascent. Steep
mid-level lapse rates of 8-9 deg C/km, combined with diurnal
heating, will result in MLCAPE of a few hundred J/kg across much of
the area. Despite weak buoyancy, the favorably-timed ascent will
contribute to thunderstorm development/intensification this
afternoon as storms approach northeast Wyoming/western South Dakota.
Some hail could occur, and a deep and well-mixed boundary layer will
lead to high-based convection capable of isolated strong/damaging
gusts through early evening, with intensities diminishing thereafter
as nocturnal cooling commences.
...Northeast North Carolina/southeast Virginia...
A surface low southeast of Cape Hatteras is forecast to move towards
the North Carolina coast through 12z Tuesday, with a belt of
stronger low-level flow developing north/northwest of the low.
Variability remains regarding the forecast location of the low and
strength of low-level winds, however a conditional risk for a
tornado would exist late tonight through early Tuesday morning with
stronger convective elements, should sufficient low-level hodograph
curvature develop as high theta-e air is advected west.
...Far northern Minnesota...
Thunderstorm development is expected this afternoon within a
northwest-southeast oriented arc from southeast Manitoba across
northeast Ontario as a shortwave trough becomes increasingly
negatively tilted while lifting northeast. Although development
south of the international border is uncertain, some global guidance
(and a convection-allowing model or two) suggest isolated
development is possible. Moderate buoyancy and effective shear of
35-40 kt over far northern Minnesota suggest a conditional risk for
severe wind/hail would exist if/where storm development occurs.
...Missouri/Mid-South..
Near and west/southwest of a residual front, a few strong/locally
damaging wind gusts will be possible again this afternoon with
pulse-type storms within a weakly-sheared but strongly unstable
(MLCAPE of 2500-3000 J/kg) thermodynamic environment.
..Guyer/Thornton.. 09/15/2025
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 PM CDT Mon Sep 15 2025
Valid 161200Z - 171200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE CENTRAL PLAINS...
...SUMMARY...
Isolated strong to severe thunderstorms are possible on Tuesday
across portions of the central Plains.
...Synopsis...
A positively tilted trough will move through the northern Great
Basin and eventually reach the High Plains by early Wednesday
morning. A weak surface trough/cold front will be positioned from
northern Minnesota southwestward into the central High Plains.
Another weak surface trough will extend farther south into the
southern High Plains. Off the Mid-Atlantic Coast, a weak surface low
will slowly shift north and weaken with time.
...Central Plains...
With the mid-level ascent from the approaching trough not arriving
until late afternoon/evening, it is not clear how much storm
development will occur prior to 00Z. Recent CAM guidance does
suggest that convergence along the surface trough/front may be
sufficient for late afternoon storms. The strongest shear will
likely remain behind the boundary. Upper 50s to mid 60s F dewpoints
will promote around 2000-3000 J/kg MLCAPE. Storms that do develop
will not likely remain discrete for very long given boundary
parallel shear. Isolated severe gusts and large hail will be the
main hazards. Storms should generally weaken during the evening and
beyond given a weak low-level jet response.
...Southern Plains...
While greater surface heating is expected to occur in this region,
limited low-level moisture will keep overall buoyancy modest. Shear
will also be rather modest during the afternoon. A cluster or two of
storms could develop in the High Plains and move eastward, possibly
producing locally gusty winds.
...Upper Mississippi Valley...
There is a weak signal within guidance for evening/overnight storm
development along the cold front. Convergence along the boundary
will only marginally increase after dark. Forcing for ascent will
also be weak and late-arriving. Steep lapse rates could promote a
stronger storm or two with an attendant hail risk. However, with
stronger shear behind the boundary and highly uncertain initiation,
probabilities do not appear warranted.
...North Carolina/Virginia Tidewater...
A weak offshore low will mostly remain offshore. The low will be
gradually weakening, particularly by the afternoon. Low-level flow
enhancement around the low may promote some increased risk for gusty
winds with convection, but limited onshore progression of greater
buoyancy along with rain/clouds will likely prohibit any greater
threat for damaging gusts.
..Wendt.. 09/15/2025
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 PM CDT Mon Sep 15 2025
Valid 171200Z - 181200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorm potential is low on Wednesday.
...Synopsis...
An upper trough over the central/northern High Plains will make
limited progress eastward into the Plains on Wednesday. This feature
is expected to broaden and become more disorganized with time. A
surface trough/cold front from the central Plains into the southern
High Plains will similarly be mostly stationary until later in the
period. Mid-level flow in the Plains will generally remain weak with
only a modest increase behind the cold front closer to the upper
trough.
Morning clouds and precipitation are expected to be ongoing in the
central Plains and parts of the southern High Plains. Upper 50s to
mid 60s F dewpoints will be ahead of the boundary. This will lead to
weak to moderate buoyancy. Thunderstorms are likely in the Front
Range where low-end moisture and upslope flow overlap. This activity
may not be very intense given the buoyancy and uncertain low-level
thermodynamics. Thunderstorms in Kansas/Oklahoma will have greater
buoyancy, but shear will be more limited. Depending on the position
of the front and destabilization, isolated to widely scattered
thunderstorms could develop in the Raton Mesa vicinity. Marginal
northwesterly deep-layer shear could promote a couple of stronger
storms given steep lapse rates. However, confidence in a more
organized severe threat in the Plains remains low at this time.
..Wendt.. 09/15/2025
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1146 AM CDT Mon Sep 15 2025
Valid 151700Z - 161200Z
...NO CRITICAL AREAS...
...17z Update...
Easterly flow is expected to develop over portions of the western
Columbia Basin and Cascade ranges late tonight through D2/Tuesday.
With gusts of 20-25 mph possible at ridge-top level and through
gaps, some dry and breezy conditions are possible. However, the
marginal RH values and recent precipitation should keep fuels
tempered, with any fire-weather concerns expected to be brief and
localized. Otherwise, see the prior outlook for more information.
..Lyons.. 09/15/2025
.PREV DISCUSSION... /ISSUED 0142 AM CDT Mon Sep 15 2025/
...Synopsis...
A mid-level trough will become situated over the northern Rockies
today, promoting mainly quiescent fire weather conditions across the
western CONUS. Ahead of the upper trough, thunderstorms may develop
over the northern Rockies into the northern High Plains. Some of
these storms may be fast moving and high based, accompanied by
erratic wind gusts. Nonetheless, fuels are at best marginally
receptive to wildfire spread, with no fire weather highlights
introduced this outlook.
...Please see www.spc.noaa.gov/fire for graphic product...
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SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0214 PM CDT Mon Sep 15 2025
Valid 161200Z - 171200Z
...NO CRITICAL AREAS...
...Afternoon Update...
No changes, periodic offshore flow remains likely over parts of the
Northwest Coast D2/Tuesday morning and early afternoon. Winds should
weaken and return to onshore into D3/Wednesday keeping fire-weather
concerns localized at best. Otherwise, dry conditions will prevail
over the Northeast and Midwest, but winds will remain light. This
should keep fire-weather concerns low, see the prior outlook.
..Lyons.. 09/15/2025
.PREV DISCUSSION... /ISSUED 0143 AM CDT Mon Sep 15 2025/
...Synopsis...
A mid-level trough will eject into the Plains states tomorrow
(Tuesday), resulting in widespread surface high pressure
overspreading the Pacific Northwest into the northern Rockies.
Mostly quiescent fire weather conditions are expected for much of
the Interior West. One possible exception may be the Pacific
Northwest coastline, where modestly dry offshore flow is expected.
Despite the offshore flow, the relatively poor fuel receptiveness to
wildfire spread west of the Cascades, and the marginal nature of the
expected dry/breezy conditions, precludes Elevated highlights this
outlook.
...Please see www.spc.noaa.gov/fire for graphic product...
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