441
FXUS65 KSLC 240425
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1025 PM MDT Sun Aug 23 2026

.UPDATE...Showers and thunderstorms, some strong to severe,
persisted across northern Utah through sunset. These storms have
been waning in intensity over the past hour or so, and will
continue to slowly decrease in coverage and intensity into the
overnight hours. The most concentrated area of convection will
continue to lift through the northeastern CWA through midnight
with frequent lightning and periods of heavy rain. Moisture will
remain in place Monday resulting in another round of afternoon and
evening showers and thunderstorms.

&&

.KEY MESSAGES, Issued 1151 AM MDT Sun Aug 23 2026...

- There is a Marginal Risk (level 1/4) for excessive rainfall
  across most of the region through early next week.

- Thunderstorms will continue to impact the higher terrain and
  adjacent valleys through Wednesday. Another round of more
  widespread thunderstorms is increasing in likelihood for Friday
  into early next weekend.

&&

.DISCUSSION, Issued 1151 AM MDT Sun Aug 23 2026...
Strong to severe convection will develop this
afternoon and evening, with the highest probability of significant
impacts (10% chance of wind gusts in excess of 70 mph) across
northern Utah. A Slight Risk (level 2/5) for severe thunderstorms
has been issued for this area by the Storm Prediction Center.
Looking at the set-up, this morning`s 12Z sounding at KSLC already
showed almost 1000 J/kg MUCAPE but with a fairly stout amount of
convective inhibition. Latest guidance suggests this effective cap
will erode by 20-21Z, allowing for robust convective development
across northern Utah. Mean HREF SBCAPE indicates a broad area of
values near to above around 1000-1500 J/kg across northern Utah
coincident with deep layer shear around 25-30 kts.

Weak surface convergence associated with a shortwave trough
passing to the north may help to organize convection into a
quasi-linear feature, though per typical in terrain, this is
difficult to discern in model fields. The latest few HRRR runs do
show a signature of an organized line of very strong outflow
shifting across the west desert and into the Wasatch Front
between 21Z and 01Z and then continuing to be quite strong into
the Uinta County, WY area by 02-03Z. Peak wind gusts in these runs
have increased to 55kts, but given the very steep lapse rates,
relatively high instability for the Great Basin, modest deep layer
shear and low LCLs, expect storms to be able to attain cold
pool/shear balance. Saturday`s convective outflow peak was 80 mph
near Grassey on I-80...cant rule out a repeat somewhere along this
area of outflow winds this afternoon and evening.

For areas south of I-70, the heavy rain threat continues. While
HREF peak 1 hour rates have decreased over Saturday`s values, net
available moisture has only decreased subtly. Expect any stronger
thunderstorms, especially those tied to terrain features and/or
training, to be capable of rainfall rates in excess of 0.50 inches
per hour. Will need to monitor for flash flood threat across much
of this area...especially for slot canyons, normally dry washes
and recent burn scars.

With the previously mentioned upper level trough passing to the
east Monday, the best chance for strong outflow winds will shift
to mainly the Utah/Idaho border region. Convection will become
increasingly tied to the higher terrain and adjacent valleys
through Wednesday...with only isolated convection expected
Thursday as high pressure brings a drying trend to most
locations.

However...with the tropical eastern Pacific remaining quite
active, at least a portion of ensemble members indicate the next
trough approaching the Pacific Northwest will assist in shifting
remnant tropical moisture into the Great Basin by Friday. This is
something to watch moving forward.



&&

.AVIATION...

KSLC...Showers and isolated thunderstorms will persist into the
overnight hours in the vicinity of KSLC, however the chance for
lightning at the terminal will diminish below 10% after 06Z.
Brief MVFR VIS can be expected should a heavier shower or
thunderstorm move over the terminal. Winds will continue to be
outflow driven through at least 06Z, varying in direction and
speed, but will eventually become southeasterly/drainage by 09Z.
Another round of showers and thunderstorms is expected around the
general area Monday.

REST OF UTAH AND SOUTHWEST WYOMING...Showers and thunderstorms
will continue across northern Utah and southwest Wyoming into the
overnight hours, gradually decreasing in coverage and intensity
with time. Frequent lightning, gusty outflow winds to 30 kts, and
periods of MVFR VIS within heavier rain will all be possible. VFR
conditions will prevail across southern Utah. Another round of
showers and thunderstorms will develop across the area Monday
afternoon and evening potentially impacting all terminals.

&&

.FIRE WEATHER, Issued 1225 PM MDT Sun Aug 23 2026...
High pressure will remain across the Four-Corners
region through the next week. As an upper level low crosses
southern Canada into the northern Intermountain Region through
Monday, sufficient forcing for thunderstorms will continue. As a
result, strong to severe thunderstorms will impact much of
northern Utah this afternoon and evening. The most significant
threat will be strong outflow winds in excess of 60 mph, mainly
north of I-70. For locations south of I-70, strong outflow winds
up to 50 mph and very heavy rain will be the primary impacts from
thunderstorms.

Additional strong thunderstorms will develop Monday afternoon and
evening, but the threat of outflows in excess of 50 mph will
remain closer to the Utah/Idaho border. As high pressure builds
north and east in the wake of the upper level low Tuesday,
thunderstorms will become more confined to the higher terrain and
adjacent valleys through Thursday. A net drying trend will
continue, with most valleys see humidities fall to critical levels
by midweek. Another round of thunderstorms may impact more of the
state as early as Friday as another low pressure area impacts the
Pacific Northwest and pulls moisture from the tropical Pacific
northeastward into the Great Basin.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

PUBLIC...
AVIATION...
FIRE WEATHER...

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity