Mesoscale Discussion 2165
NWS Storm Prediction Center Norman OK
1231 PM CDT Sat Aug 29 2026

Areas affected...parts of northeastern Utah...southwestern/south
central Wyoming...northwestern Colorado

Concerning...Severe potential...Watch unlikely 

Valid 291731Z - 292000Z

Probability of Watch Issuance...20 percent

SUMMARY...Thunderstorms are likely to continue developing and
overspreading the region through 1-3 PM MDT, accompanied by
gradually increasing potential to produce strong to severe wind
gusts and small hail.  It is still not clear that this will require
a severe weather watch, but trends will be monitored.

DISCUSSION...Downstream of a low-amplitude short wave trough, a
corridor of strengthening frontogenetic forcing for ascent (around
and below 700 mb) has provided the primary focus for thunderstorm
development the past few hours.  This  forcing is forecast to
continue to shift east-northeastward into/across the southwestern
through south central Wyoming state border vicinity through 21-22Z. 

The environment along the baroclinic zone is relatively moist, but
with a still relatively cool boundary layer and weak to modest
low/mid-level lapse rates limiting destabilization.  Even so, shear
beneath moderate to strong westerly mid/upper flow, including speeds
of 40-50 kt within the lowest 3-4 km AGL, has been sufficient to
support at least one longer-lived vigorous cell with strong to
severe gusts and marginally severe hail southwest through south of
the Great Salt Lake this morning.

Similar strength convection appears possible over the next few
hours, east of the Wasatch, along the Uinta Mountains through the
western Colorado/Wyoming border vicinity, where ongoing insolation
is contributing to the evolution of an increasingly deeply mixed
boundary layer.  Forecast soundings suggest that profiles in lower
elevations may become characterized by 30-40 F surface
temperature/dew point spreads, with CAPE exceeding 500 J/kg.  As
this occurs, the environment may become conducive to increasing
thunderstorm development with strengthening downdrafts aiding the
downward transport of strong to severe gusts to the surface.

..Kerr/Mosier.. 08/29/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CYS...RIW...GJT...SLC...

LAT...LON   40351209 41661088 42070897 41890772 40950751 40350926
            39961091 40351209 

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1129 AM CDT Sat Aug 29 2026

Valid 291630Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
NEVADA ACROSS NORTHERN UTAH INTO FAR SOUTHWEST WYOMING...

...SUMMARY...
Widely scattered strong to severe storms are expected across parts
of the northern Great Basin, northern/central Rockies, and northern
Plains. Severe wind gusts are the main threat.

...Great Basin through the central Rockies...
Enhanced mid-level southwesterly flow aloft exists between the upper
ridging centered over the southern High Plains and a shortwave
trough moving through the Pacific Northwest. 12Z SLC sounding
sampled this enhanced flow well, reporting a belt of 50-55 kt wind
around 600 to 500 mb. This sounding also sampled the increased
mid-level moisture within this belt of stronger flow, resulting
precipitable water over 1.1".

Modest heating of this airmass is expected to foster moderate
buoyancy, although the widespread cloudiness could keep the airmass
from fully destabilizing. Most RAP soundings across the region
maintain lingering convective inhibition from UT into southern WY.
Even so, the combination of modest buoyancy, mid-level moisture, and
ascent attendant to a low-amplitude shortwave trough progressing
through the region will support scattered to numerous thunderstorms
from eastern NV across UT into northwest CO/southern WY. Some
isolated hail is possible with the strongest cores (which could
briefly acquire supercellular characteristics), but the primary
severe risk is strong to severe wind gusts. Highest severe coverage
is still expected from east-central NV into northern UT where the
greatest afternoon buoyancy is forecast.

...Northeast CO/eastern WY/NE Panhandle into the western/central
Dakotas...
High-based showers and thunderstorms along the leading edge of the
strongest ascent attendant to the shortwave trough moving through
the Great Basin and central Rockies should emerge into a diurnally
destabilized and moderately buoyant airmass from northeast CO into
eastern WY and the NE Panhandle during the late afternoon/early
evening. This could result in reintensification, and a risk for both
large hail and damaging gusts across the region throughout the
evening. Most of the guidance was overly aggressive with
destabilization and buoyancy across this region yesterday, and there
is some concern that cloud cover could again limit heating. That
being said, there is a pocket of greater low-level moisture across
SD and the region is currently under widely scattered cloud cover.
Enhanced westerly flow atop low-level easterlies will support at
least moderate deep-layer shear, so any updrafts that can mature
should be able to organize, with an attendant risk for large hail
and damaging gusts.

...AZ...
12Z PHX sounding sampled moderate mid-level moisture atop warm and
dry low levels. Scattered thunderstorm development is anticipated
across much of the region. Vertical shear is weak and a largely
disorganized storm mode is anticipated. Still, given the high storm
bases and steep low-level lapse rates, isolated strong to severe
gusts are possible this afternoon and evening.

..Mosier/Moore.. 08/29/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1224 PM CDT Sat Aug 29 2026

Valid 301200Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
NORTHERN PLAINS...

...SUMMARY...
At least isolated severe storms, accompanied by mainly a severe wind
and hail threat, are possible across portions of the northern Plains
on Sunday.

...Discussion...
A shortwave trough will move across the northern Rockies on Sunday,
with upper low deepening over SK. This trough will bring increasing
wind fields and cooling aloft across the northern High Plains and
Dakotas late in the day and overnight. At the surface, low pressure
will develop during the afternoon from near the MT/ND border
southward into western SD ahead of a cold front, which will move
across the Dakotas overnight. A warm front will also extend eastward
from SD into southern MN, WI and Lower MI, where mid to upper 60s F
dewpoints are likely to exist.

Isolated elevated storms may be ongoing Sunday morning from parts of
southern MN into IA, WI and Lower MI, though models are quite
variable. Winds at 850 mb will be veered to west/southwest, and
height rises will occur throughout the day. As such, any activity
that does develop should remain disorganized, with low severe
chances if any.

During the afternoon, storms are most likely to develop along the
cold front from eastern MT into northeast WY, northwest SD, and into
much of ND. These may be mixed mode storms, as winds below 500 mb
will remain relatively weak, though high level winds will be
stronger. Scattered severe gusts or hail above 1.00" appear likely
through the night as activity pushes across ND and into northern MN.

Farther south, scattered strong to severe wind gusts may occur over
the central High Plains as high based convection moves off the high
terrain of CO/WY, aided by 30-40 kt midlevel westerlies. Steep
low-level lapse rates/deep mixed layers may support localized wind
potential.

..Jewell.. 08/29/2026

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1023 AM CDT Sat Aug 29 2026

Valid 291700Z - 301200Z

No changes were made to the Elevated wind/RH area in place over
portions of the Pacific Northwest and adjoining regions as well the
area over the southern Plains. The latest forecast guidance remains
on track with previous outlook issuances. Surface observations as of
late this morning indicate south-southwesterly winds of 15-20 mph in
place over the southern Plains as the surface trough tightens the
pressure gradient. A well-mixed boundary layer amid hot surface
temperatures will support afternoon RHs below 20-25% across the
highlighted area.

Sufficient instability (CAPE near 100-500 J/kg) will support wet and
dry thunderstorms over portions of north-central WA later this
afternoon amid increasing dynamic lift within the left exit region
of the jet streak ahead of the approaching trough. While moisture
content ahead of this trough remains low (precipitable water values
near 0.5-0.6"), much below normal temperatures today and
accumulating rainfall likely on Day 2/Sunday where convection is
most likely to occur this afternoon. Continued cooler than normal
conditions and higher RHs persist through much of the coming week
over this area as well. While a few new lightning ignitions are not
out of the question due to dry (but moistening) fuels, they will be
significantly moderated by the aforementioned environmental
conditions over the next several days.

..Stearns.. 08/29/2026

.PREV DISCUSSION... /ISSUED 1215 AM CDT Sat Aug 29 2026/

...Synopsis...
...Southeast Oregon into northeast California and northwest
Nevada...
Surface winds are expected to increase ahead of a boundary on
Saturday. Winds of 15-20 mph will be possible during the afternoon.
Elevated fire weather is expected within a narrow zone of 15-20% RH
that will reside between the surface boundary and richer mid-level
moisture/clouds to the south east.

...Southern High Plains into south-central Kansas...
The presence of a surface trough from the central Plains into the
southern High Plains will allow 15-20 mph to develop by the
afternoon. Hot temperatures underneath the upper ridge will help
lower humidity to 20-25%. Drought-stressed fuels will support an
elevated fire weather threat despite recent rainfall.

...Please see www.spc.noaa.gov/fire for graphic product...