278
FXUS65 KSLC 131831
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1231 PM MDT Thu Aug 13 2026

.KEY MESSAGES...

- Monsoonal moisture looks to bring daily chances for showers and
thunderstorms across much of UT through Friday before drying out
this weekend.

- A flash flood threat exists across southwest UT and the central UT
mountains this afternoon. Confidence is highest regarding impacts
across southwest UT.

- A severe weather threat exists across northern UT today with
damaging winds (>58mph) as the primary threat.


&&

.DISCUSSION...Troughing strengthens across much of the West Coast
today as ridging weakens somewhat across the southwest today
enabling another monsoonal moisture push this afternoon. This will
result in a flash flood threat across southwestern UT and portions
of central UT this afternoon, as well as a severe weather threat
across northern UT, western UT, and extreme southwestern UT.
Following todays threat, conditions look to dry out through the
weekend, potentially into midweek next week.

An H5 trough situated over the PNW continues to deepen this
afternoon with multiple shortwave perturbations progressing SW to NE
across the great basin will provide ascent for multiple rounds of
scattered showers and thunderstorms this afternoon across UT.
Currently across southwestern UT, leftover subsidence from earlier
thunderstorms this morning has resulted in a convective lull which
is expected to last through around noon-2pm MT this afternoon as a
deepening shortwave pushes into the state with flow enhancing aloft.
The flooding threat is forecast to continue to increase with these
storms through the afternoon as PWATs continue to increase,
characterized by values in excess of 1.2", perhaps higher as CAM
guidance has not handled this well today (i.e. recent Dugway
sounding characterized by 1.3" PWATs in the West Desert), indicating
that values may actually be higher across SW UT. Additionally,
training storms may result in rather high rainfall rates reaching
and/or exceeding 0.5"/hr. This raises concern for recent burn scars,
such as Cottonwood, Forsyth, Monroe Canyon, France Canyon, Silver
King, and the new Widemouth 2 burn scar.

Further north, showers are ongoing across much of northern UT
spurred by WAA in the midlevels. These showers will continue to
dissipate through the morning, with stronger storms expected to form
after 4pm MT as the shortwave impulse deepens with a 30kt H5 jet
developing overhead. Strong upper diffluence is forecast to develop
with perhaps multiple 50kt jet streaks developing overhead around
the time of CI, resulting in EBWD values from 30-40kts this
afternoon supporting the potential for a couple supercells this
afternoon. The primary threat with these thunderstorms are severe
wind gusts in excess of 58mph, particularly if they can root
effectively within the boundary layer this afternoon. Some
uncertainty regarding this exists due to persistent cloud cover,
though diurnal heating with current cloud breaks supports some
airmass recovery this afternoon in the midst of dewpoints in the
upper 50s to low 60s. Lastly, this threat is enhanced as the early
morning convection has left behind a few different outflow
boundaries, in particular north of the airport toward the bountiful
area as well as another potentially closer to the ID border. This
will locally enhance vorticity, and with daytime heating expected to
increase MLCAPE to at least 150J/kg, support some stronger and
potentially longer-lived storms developing.

With the ridge pushing east and dry air advecting in tomorrow with
the aforementioned trough pushing in, PoPs decrease somewhat
tomorrow afternoon statewide. The flash flood threat exists across
far southwest UT once again as the moisture reservoir of higher
PWATs remains in place, though precip will begin to favor higher
terrain otherwise. Into this weekend through potentially midweek
next week, mid-level moisture will remain in place as the ridge
continues sliding east favoring terrain-driven thunderstorms and a
lower-elevation drying trend. Ensemble guidance continues to push
back the true return to monsoonal moisture, potentially after
Wednesday next week.

&&

.AVIATION, Issued 1230 PM MDT Thu Aug 13 2026...
KSLC, Issued 1230 PM MDT Thu Aug 13 2026...
Watching for the development of thunderstorms
around the terminal this evening, with storm motion from southwest
to northeast. These storms could drive some gusty and erratic winds,
with the peak gusts potentially pushing 45 kts. Most likely timing
remains 23-01Z though could see activity as early as 19Z and persist
as late as 03Z. Storms directly overhead the terminal have the
potential to produce significant heavy rainfall. A currently very
low probability of overnight storms between 06-10Z exists.

REST OF UTAH AND SOUTHWEST WYOMING...Showers and thunderstorms
across northern Utah and southwest Wyoming persist, with recent
observations indicating these cells are producing very heavy
rainfall and gusty winds. There is a 5-10% chance of wind gusts in
excess of 58 mph near thunderstorms this evening. For southern Utah,
a lesser wind potential exists with heavy rain, low ceilings, and
reduced visibility (MVFR to IFR) in these rain shafts the primary
threat.

&&

.FIRE WEATHER...A monsoonal surge will bring showers and
thunderstorms with the potential for severe wind gusts (>58mph) to
much of UT today as well as the potential for flash flooding
across southwestern and central UT. Both severe and flash flooding
threats taper off somewhat tomorrow, though afternoon
thunderstorms capable of heavy rain and gusty and erratic outflow
winds are expected. Humidities will begin to decrease heading into
next week with lower elevation locations potentially dropping
below 20% starting Monday as we continue to dry out. A return to
monsoonal moisture is possible following midweek, though this
remains uncertain at this time and the drying trend remains
somewhat favored through the long term.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch through Friday morning for UTZ116-117-122>129.

WY...None.
&&

$$

PUBLIC...Worster
AVIATION...Wessler
FIRE WEATHER...Worster

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