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.
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/TVbtxM
