No watches are valid as of Tue Sep 22 22:02:02 UTC 2026.MD 2325 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTHERN UTAH INTO SOUTHEAST IDAHO
Mesoscale Discussion 2325
NWS Storm Prediction Center Norman OK
0334 PM CDT Tue Sep 22 2026
Areas affected...Northern Utah into southeast Idaho
Concerning...Severe potential...Watch unlikely
Valid 222034Z - 222230Z
Probability of Watch Issuance...5 percent
SUMMARY...Marginally severe hail and isolated severe gusts are
possible this afternoon. Overall severe coverage should remain too
limited for a watch.
DISCUSSION...A compact upper low is evident on water vapor imagery
along northern portions of the Utah/Nevada border. Lift from this
feature is promoting scattered convection across northern/eastern
portions of the Great Basin this afternoon. Some activity near the
Great Salt Lake has intensified during the last half hour. With
additional heating, other storms may similarly increase in strength.
The strongest shear exists in eastern Utah/western Colorado where
the mid-level jet core is located. However, these areas have
remained cooler/less unstable. Severe potential will likely be
maximized along the northwest periphery of the mid-level jet where
MLCAPE has risen to 500-750 J/kg. Temperatures near the upper low
are cold enough to support marginally severe hail despite weaker
shear. Isolated severe gusts are also possible.
..Wendt/Mosier.. 09/22/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...SLC...PIH...
LAT...LON 39891274 39921351 40691376 41561318 42441190 42471152
42181130 41251136 40121240 39891274
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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.
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1219 PM CDT Tue Sep 22 2026
Valid 231200Z - 241200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN TN AND VICINITY...
...SUMMARY...
Strong to locally severe storms are possible across parts of eastern
Tennessee and vicinity on Wednesday.
...Eastern TN and vicinity...
A mid/upper-level trough will remain in place over most of the East
on Wednesday. A reinforcing shortwave trough and attendant jet
maximum are forecast to move from the lower Ohio Valley toward the
southern Appalachians through the day. A narrow zone of moderate
destabilization is expected to develop during the afternoon from
northeast AL into eastern TN and southeast KY, in the vicinity of an
inverted surface trough. The approaching shortwave trough and
terrain-related circulations will result in thunderstorm development
during the afternoon.
The greatest storm coverage is currently expected in the vicinity of
eastern TN, where effective shear will generally be in the 25-30 kt
range, with modestly elongated mid/upper-level hodographs. The
environment will support at least brief storm organization, with
localized hail and strong/damaging gusts possible. A
Level-1/Marginal Risk has been added where relative confidence is
highest in strong diurnal storm development. Deep-layer shear will
be somewhat stronger into central AL/west-central GA, though
substantial midlevel dryness and warmer temperatures aloft may tend
to limit storm coverage with southward extent.
...Northern High Plains...
A mid/upper-level shortwave trough will move across the Dakotas on
Wednesday. The relatively early timing of this system will not be
ideal for surface-based development later in this afternoon across
the northern High Plains, where some diurnal destabilization is
expected. Isolated strong storm development cannot be ruled out in
this area, while generally weak elevated convection is expected
farther east across the eastern Dakotas into MN.
...Southern High Plains...
Relatively widespread convection is expected from eastern NM into
the OK/TX Panhandles, in association with a mid/upper-level trough
moving northward out of Mexico. Generally weak lapse rates and
buoyancy are expected to limit severe potential, though a strong
storm or two cannot be ruled out, given the presence of veering wind
profiles and 25-35 kt of effective shear.
..Dean.. 09/22/2026
SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0143 PM CDT Tue Sep 22 2026
Valid 241200Z - 251200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not expected on Thursday.
...Synopsis...
Large-scale upper-level troughs are expected to persist across the
eastern and western CONUS on Thursday, with an upper ridge expected
to remain in place across the south-central CONUS. Across the East,
favorable low-level moisture will become increasingly confined to
the immediate Gulf Coast and FL. Farther west, seasonably rich PW
will support thunderstorm potential across a broad region from the
Southwest into the High Plains, though generally weak lapse
rates/buoyancy and modest deep-layer flow/shear are currently
expected to limit organized severe potential.
..Dean.. 09/22/2026
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