SPC Sep 21, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Mon Sep 21 2026

Valid 211300Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE SOUTHEAST INTO THE CENTRAL APPALACHIANS AND OVER THE TEXAS SOUTH
PLAINS...

...SUMMARY...
Isolated damaging wind gusts are possible this afternoon from parts
of the Southeast into the southern and central Appalachians. An
isolated risk for large hail and severe gusts is forecast over parts
of the Texas South Plains later today.

...Southeast/Southern and Central Appalachians...
Radar mosaic this morning shows a parade of three MCVs moving
eastward over the OH Valley into the central Appalachians primarily
to the immediate cool side of a cold front. This front will aid in
focusing storm development today over the northern portion of the
Marginal Risk where slightly stronger flow fields are expected
(i.e., KY-WV-VA). By afternoon, the front is forecast to be
positioned from northern Mississippi northeastward to western
Virginia. Ahead of the front, a moist airmass will be in place with
surface dewpoints in the upper 60s to lower 70s F from the lower
Mississippi Valley northeastward into WV. As moderate buoyancy
develops by early to mid afternoon, scattered to numerous single and
multicell thunderstorms are expected to form. A few of the stronger
downdrafts will likely yield a threat for strong to locally severe
gusts (50 to 60 mph) and pockets of wind damage before weakening by
the early evening.

...TX South Plains...
A mid to upper-level ridge will gradually shift eastward over the
southern High Plains during the period as an upper trough over
eastern OK this morning continues eastward and becomes increasingly
displaced from west TX. A frontal zone and residual outflow will
become draped over the TX South Plains during the afternoon. Model
guidance indicates at least scattered storms developing within a
moist plume extending west-northwestward into the Caprock/South
Plains vicinity during peak heating. A couple of stronger
thunderstorms may yield an isolated risk for large hail/severe gusts
before dissipating during the evening.

..Smith/Mead.. 09/21/2026


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SPC Sep 21, 2026 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 AM CDT Mon Sep 21 2026

Valid 211200Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE SOUTHEAST INTO THE SOUTHERN AND CENTRAL APPALACHIANS...

...SUMMARY...
Thunderstorms with isolated severe wind gusts will be possible this
afternoon from parts of the Southeast into the southern and central
Appalachians.

...Southeast/Southern and Central Appalachians...
A cold front will advance southeastward across the southern and
eastern U.S. today. By afternoon, the front is forecast to be
positioned from northern Mississippi northeastward to western
Virginia. Ahead of the front, a moist airmass will be in place with
surface dewpoints in the upper 60s to mid 70s F from the lower
Mississippi Valley northeastward into West Virginia. As surface
temperature warm, an axis of moderate instability will develop ahead
of the front from central Mississippi northeastward into western
North Carolina, where MLCAPE should peak in the 2000 to 3000 J/kg
range. Low-level convergence will increase along the front during
the day, which will be favorable for scattered to numerous
thunderstorm development. Although deep-layer shear will be weak
along and near the instability axis, low-level lapse rates will
become steep in the afternoon. The thermodynamic environment should
be favorable for isolated severe wind gusts with single cells or
disorganized multicells. The threat should be largely diurnal but
may persist into the early evening in areas that destabilize the
most.

..Broyles/Thornton.. 09/21/2026


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SPC Sep 21, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Sep 20 2026

Valid 210100Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL HIGH PLAINS....

...SUMMARY...
Thunderstorms with large hail and severe wind gusts will be possible
this evening across parts of the central High Plains. A few severe
wind gusts may also occur from the Ozarks northeastward into the
Ohio Valley.

...Central High Plains...
The latest water vapor imagery shows a shortwave mid-level trough
over eastern Colorado. An axis of moderate instability, with MLCAPE
in the 1500 to 2000 J/kg range, is analyzed by the RAP just ahead of
this feature from near the Colorado-Kansas state line southeastward
into the Oklahoma Panhandle. An isolated supercell is currently
ongoing near the instability axis near Lamar, Colorado. RAP forecast
soundings ahead of this cell across far southwest Kansas early this
evening have MLCAPE in the 1500 to 2000 J/kg range, 0-6 km shear
near 40 knots and 700-500 mb lapse rates around 7 C/km. This
environment will continue to support supercells capable of large
hail and wind damage. The threat could persist into the mid to late
evening with parts of southwest Kansas and the Oklahoma Panhandle
being affected. Later this evening, short-term model forecasts also
suggest that redevelopment may occur to the east of the Denver
Metro, with a new cluster potentially tracking southeastward near
the instability axis. This activity could also pose a large hail and
wind damage threat.

...Ozarks into the Ohio Valley...
Several minor perturbations, embedded in westerly flow aloft, appear
to moving through a corridor from the Ozarks eastward into the Ohio
Valley. The most pronounced feature appears to be located in
southeastern Indiana, ahead of which a small cluster of severe
storms is ongoing. Along the projected track of these storms, the
RAP has MLCAPE in the 1200 to 1500 J/kg range with 0-6 km around 35
knots. This should continue to support an isolated wind-damage
threat for a couple more hours early this evening...see MCD 2319.

Further southwest into the parts of the Ozarks and mid Mississippi
Valley, moderate instability is analyzed by the RAP from far
northeast Oklahoma northeastward into south-central Illinois.
Isolated to scattered thunderstorms are ongoing near the instability
axis. These storms may be capable of producing isolated severe wind
gusts for another hour or two this evening...see MCD 2318.

..Broyles.. 09/21/2026


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SPC Sep 20, 2026 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Sun Sep 20 2026

Valid 201630Z - 211200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL AND EASTERN OKLAHOMA...AND FROM EASTERN COLORADO INTO FAR
WESTERN KANSAS...

...SUMMARY...
Thunderstorms with severe wind gusts and large hail will be possible
this afternoon and evening across parts of Oklahoma and from eastern
Colorado into far western Kansas. Isolated severe gusts and hail
will also be possible in parts of the southern Plains, and from the
Ozarks eastward into the Ohio Valley.

...Central/North TX into central/eastern OK...
Surface analysis places a low over central OK, along a cold front
that arcs from northeast OK into southwest OK and then back up
through the central TX Panhandle. This low also precedes a shortwave
trough moving into western OK. The cold front is forecast to shift
southward/southeastward today as the shortwave continues eastward.
The airmass ahead of this front will be warm, moist, and moderately
buoyant, and thunderstorm development is expected from
central/eastern OK into central TX. Mid-level flow is slightly
stronger across OK, supporting a greater potential for strong to
severe storms. A more isolated severe risk exists across TX where a
more disorganized storm mode is likely. Primary threat is damaging
gusts from 55 to 65 mph.

...Central High Plains...
An easterly component to low-level flow north of the surface front
will maintain a fetch of moisture (50s deg F surface dewpoints)
across eastern CO this afternoon. This moisture, combined with
heating and cool temperatures aloft, will enable moderate
destabilization by afternoon. Thunderstorm development is expected
as ascent attendant to the mid-level cyclone over WY persists across
the region. Moderate mid-level westerly flow will also persist
throughout the base of this cyclone, resulting in moderate to strong
vertical shear across the region this afternoon and evening. Storm
coverage is expected to remain isolated to widely scattered (largely
due to cooler surface temperatures and some lingering convective
inhibition), but any storms that do form and mature will likely be
supercellular. Primary severe hazard is large hail (1 to 2.5 inches
in diameter), but isolated severe gusts are possible as well. Some
lingering severe risk may eventually develop over southeast CO late
this evening and spread into the OK Panhandle overnight.

...Ozarks into the Mid Mississippi and Ohio Valleys...
Recent surface analysis places lows over central PA, central IL,
central MO, and central OK. An arcing stationary boundary extends
between these features, with this boundary largely demarcated by a
subtle wind shift. Current water vapor satellite imagery shows
several convectively augmented vorticity maxima within this corridor
as well. These vorticity maxima are forecast to progress
eastward/northeastward along the northern periphery of a weakened
mid-level anticyclone centered over the northwest Gulf Coast,
augmenting low-level convergence and helping to support
afternoon/evening thunderstorms from the OH Valley into
central/southern MO.

Despite ample low-level moisture, relatively warm temperatures aloft
will likely mitigate the overall buoyancy. Even so, steep low-level
lapse rates and moderate mid-level flow could still support some
bowing line segments capable of damaging gusts. Highest thunderstorm
coverage this afternoon and evening is expected from
central/southern IN into southern OH, with another corridor of
relatively higher coverage developing across central MO later this
evening as well. Both of these corridors are downstream of a
previously mentioned vorticity max, and represent areas of greater
severe potential.

..Mosier/Chalmers.. 09/20/2026


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