SPC Sep 23, 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
0726 AM CDT Wed Sep 23 2026

Valid 231300Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
WESTERN DAKOTAS AND SOUTHERN APPALACHIANS...

...SUMMARY...
Isolated severe thunderstorms are possible this afternoon across
parts of the western Dakotas and southern Appalachians.

...Western Dakotas...
Water-vapor imagery this morning shows a mid-level trough moving
northeast across WY/MT. This upper disturbance will move into the
western Dakotas by late afternoon and gradually deamplify as it
reaches the Red River Valley by daybreak Thursday. A lee trough
will facilitate the maintenance of a moisture plume extending
northward from the central High Plains into the western Dakotas.
Model forecast soundings show around 1000 J/kg MLCAPE developing
with marginally steep lapse rates. Widely scattered thunderstorms
are forecast to develop as convective inhibition erodes in the
vicinity of the lee trough and the Black Hills this afternoon. Some
elongation of the hodograph may aid in some storm organization
potential, with the stronger thunderstorms perhaps yielding an
isolated risk for marginally severe hail/gusts through early
evening.

...Southern Appalachians...
A mid-level vorticity maximum will move southeast today from the
lower OH Valley into the southern Appalachians. An inverted trough
co-located with a regionally greater reservoir of low-level moisture
(i.e., surface dewpoints in the 60s deg F), will focus thunderstorm
development this afternoon. Extensive low cloud cover will likely
inhibit strong heating and lends considerable uncertainty regarding
destabilization and the potential for stronger thunderstorm
development. Forecast soundings show that despite limited low to
mid-level lapse rates, perhaps 250-750 J/kg MLCAPE may develop by
mid afternoon. Strong to locally damaging thunderstorm gusts may
occur with the stronger storms. Have removed low hail probabilities
due in part to the 12 UTC Nashville, TN raob depicting poor 700-500
mb lapse rates (4.8 deg C/km) and limited forecast buoyancy.

..Smith/Mead.. 09/23/2026


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SPC Sep 23, 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
1231 AM CDT Wed Sep 23 2026

Valid 231200Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE SOUTHERN
APPALACHIANS...

...SUMMARY...
Thunderstorms with isolated severe wind gusts and hail will be
possible this afternoon across parts of the southern Appalachians.

...Southern Appalachians...
At mid-levels, a low and an associated shortwave trough will move
eastward across the Ohio and Tennessee Valleys today. Ahead of the
system, a surface trough will be in place from central Alabama
northeastward into eastern Tennessee. Surface dewpoints near the
trough will be in the mid to upper 60s F, which will help MLCAPE
increase into the 1000 to 1500 J/kg by afternoon. As low-level
convergence becomes focused this afternoon along and near the
trough, scattered thunderstorms will form. RAP forecast soundings
near the instability axis at 21Z have 0-6 km shear in the 30 to 40
knot range, with steep low-level lapse rates. This may support a
potential for isolated severe gusts and hail with the stronger
multicells. The severe threat should be concentrated around peak
heating.

..Broyles/Thornton.. 09/23/2026


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SPC Sep 22, 2026 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Tue Sep 22 2026

Valid 222000Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR MUCH OF UTAH
INTO ADJACENT PARTS OF WYOMING AND COLORADO... AND ACROSS A PORTION
OF THE SOUTHEAST...

...SUMMARY...
An isolated threat for severe wind gusts is expected today in Utah
into southwest Wyoming and western Colorado. Thunderstorms capable
of strong to locally severe damaging gusts are also possible across
parts of the Southeast.

...20Z Update Southeastern US...

The primary forecast update was to move the Marginal Risk area
further south and east into central Georgia and southern Alabama,
where thunderstorms have developed in an unstable airmass with steep
low-level lapse rates. While a lack of vertical shear will support a
disorganized storm mode, water-loaded downdrafts and associated
severe thunderstorm gusts will be possible this afternoon into the
early evening. Additional thunderstorm development along the diffuse
cold front across Tennessee into northern Alabama will continue to
progress into the Marginal Risk area, posing a primarily damaging
wind threat.

Otherwise, the forecast largely remains on track with minor
adjustments to the thunder area based on current guidance. Damaging
wind gusts are still anticipated this afternoon across portions of
Utah into southwestern Wyoming and western Colorado. See the
previous discussion for more detail.

..Halbert/Lyons.. 09/22/2026

.PREV DISCUSSION... /ISSUED 1124 AM CDT Tue Sep 22 2026/

...Utah into southwest Wyoming and western Colorado...
Recent water-vapor imagery shows a potent shortwave trough over the
western Great Basin. Recent mesoanalysis estimates a belt of
stronger mid-level flow extends throughout the eastern periphery of
this wave from northern AZ into central UT. This shortwave is
forecast to continue slowly northeastward today, with the
accompanying belt of stronger flow extending through northern UT
into western WY. Scattered to numerous thunderstorms are expected
this afternoon and evening across the region as lift attendant to
this wave interacts with the modestly moist and buoyant airmass
across the region. Buoyancy will likely remain modest (i.e. MLCAPE
less than 1000 J/kg. Even so, moderate to strong vertical shear
associated with the stronger mid-level flow will support organized
storm structures. This shear combined with cold mid-level
temperatures will support the potential for large hail.
Additionally, high cloud bases and steep low-level lapse rates
suggest strong gusts are possible with any of the more robust
storms. This activity will eventually move into western CO and
southwest WY towards the late afternoon/early evening with isolated
severe gusts and/or large hail remaining possible within the
stronger cores and associated outflows.

...Southeast...
Recent surface analysis places a diffuse cold front from the
Arklatex northeast into far western VA where it intersects the wedge
front over the Mid-Atlantic. This front is expected to gradually
shift southward today, interacting with the moist airmass across the
Southeast to support thunderstorm development. The strongest
buoyancy (i.e. 1500 to 2000 J/kg of MLCAPE) is expected from
western/central SC into central AL, where afternoon temperatures
will likely reach the 90s amid low 70s dewpoints. Weak low to mid
tropospheric flow was sampled by regional soundings, with the very
weak vertical shear limiting the overall storm strength and
persistence. Some of the stronger water-loaded downdrafts could
produce strong gusts with pockets of wind damage into the early
evening. Low wind probabilities were trimmed out of southwest VA and
adjacent western NC/northeast TN where temperatures will remain
cool, limiting buoyancy. Low wind probabilities were also trimmed
across central MS where only isolated storm coverage is anticipated.


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SPC Sep 22, 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
1124 AM CDT Tue Sep 22 2026

Valid 221630Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR MUCH OF UTAH
INTO ADJACENT PARTS OF WYOMING AND COLORADO...AND ACROSS A PORTION
OF THE SOUTHEAST...

...SUMMARY...
An isolated threat for severe wind gusts is expected today in Utah
into southwest Wyoming and western Colorado. Thunderstorms capable
of strong to locally severe damaging gusts are also possible across
parts of the Southeast.

...Utah into southwest Wyoming and western Colorado...
Recent water-vapor imagery shows a potent shortwave trough over the
western Great Basin. Recent mesoanalysis estimates a belt of
stronger mid-level flow extends throughout the eastern periphery of
this wave from northern AZ into central UT. This shortwave is
forecast to continue slowly northeastward today, with the
accompanying belt of stronger flow extending through northern UT
into western WY. Scattered to numerous thunderstorms are expected
this afternoon and evening across the region as lift attendant to
this wave interacts with the modestly moist and buoyant airmass
across the region. Buoyancy will likely remain modest (i.e. MLCAPE
less than 1000 J/kg. Even so, moderate to strong vertical shear
associated with the stronger mid-level flow will support organized
storm structures. This shear combined with cold mid-level
temperatures will support the potential for large hail.
Additionally, high cloud bases and steep low-level lapse rates
suggest strong gusts are possible with any of the more robust
storms. This activity will eventually move into western CO and
southwest WY towards the late afternoon/early evening with isolated
severe gusts and/or large hail remaining possible within the
stronger cores and associated outflows.

...Southeast...
Recent surface analysis places a diffuse cold front from the
Arklatex northeast into far western VA where it intersects the wedge
front over the Mid-Atlantic. This front is expected to gradually
shift southward today, interacting with the moist airmass across the
Southeast to support thunderstorm development. The strongest
buoyancy (i.e. 1500 to 2000 J/kg of MLCAPE) is expected from
western/central SC into central AL, where afternoon temperatures
will likely reach the 90s amid low 70s dewpoints. Weak low to mid
tropospheric flow was sampled by regional soundings, with the very
weak vertical shear limiting the overall storm strength and
persistence. Some of the stronger water-loaded downdrafts could
produce strong gusts with pockets of wind damage into the early
evening. Low wind probabilities were trimmed out of southwest VA and
adjacent western NC/northeast TN where temperatures will remain
cool, limiting buoyancy. Low wind probabilities were also trimmed
across central MS where only isolated storm coverage is anticipated.

..Mosier/Wendt.. 09/22/2026


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