680
FXUS65 KSLC 182346
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
546 PM MDT Tue Aug 18 2026

.KEY MESSAGES, Issued 928 AM MDT Tue Aug 18 2026...


- Building high pressure will bring a steady warming trend in
  temperatures as conditions dry, bringing a threat of isolated
  critical fire weather conditions.

- Monsoon moisture will move back into Utah and southwest Wyoming
  late in the week, persisting through at least early next week.
  This will bring an increased threat of showers and thunderstorms
  capable of producing flash flooding.

&&

.DISCUSSION, Issued 928 AM MDT Tue Aug 18 2026...
High pressure is centered near the Utah/Nevada
border this morning with some shortwave energy rippling over the
top of it. Thus, seeing clear skies except for southwest Wyoming
and areas near the Utah/Idaho border. Satellite derived PWs
indicate values primarily in the 0.7 to 1.0 inch range, enough
moisture for some afternoon convective development. Coverage
should be generally isolated in nature, with the best coverage
over northeastern portions of the area, closer to the upper jet
associated with the passing shortwave energy.

Under the influence of the ridge, high temperatures today will be
similar to yesterday with maxes near seasonal normals. With the
ridge expected to amplify and move overhead Wednesday into
Thursday, temperatures will steadily warm, with maxes averaging up
to 10F above seasonal normals by Thursday, with the greatest
departure from normal over northern portions of the area. The
airmass will dry out during this time, with relative humidities
approaching critical values for portions of western Utah. Locally
breezy conditions could bring a few pockets of critical fire
weather conditions, but overall the threat is quite isolated.
HeatRisk values are forecast to move into the red (major) range
for some northern Utah valleys on Thursday, including the west
desert and parts of the Wasatch Front. Overall, though, the
increased threat of heat related illness will be mitigated due to
overall acclimation during the season.

By Friday, there is high confidence that the ridge will move its
axis to the monsoon favored position over the Four Corners,
drawing deep moisture back northward and increasing the potential
of showers and thunderstorms capable of producing flash flooding.
This will also remove the threat of critical fire weather
conditions and bring temperatures back to near normal for this
time of year. The monsoon moisture is expected to remain in place
through at least early next week.





&&

.AVIATION...

KSLC...Northwesterly winds will likely shift to light and
southeasterly around 03-04z. However, there is low confidence in
wind direction overnight, with potential to go back to northerly
around 4-7kts between 06-11z. Otherwise, expect VFR conditions with
FEW-SCT mid-level clouds.

REST OF UTAH AND SOUTHWEST WYOMING...Showers and isolated
thunderstorms across eastern Utah will gradually diminish by 04-05z,
with quiet conditions and terrain-driven winds expected overnight.
Isolated thunderstorms will redevelop Wednesday afternoon across
primarily eastern Utah with chances for gusty outflow winds. VFR
conditions will prevail.

&&

.FIRE WEATHER, Issued 414 PM MDT Tue Aug 18 2026...
High pressure to the west of Utah will bringing a
warming and drying trend through Thursday, bringing temperatures
up to 10F above seasonal normals by Thursday afternoon. Relative
humidities will drop, with pockets of critically low RH values
developing by Thursday. Winds could be enough to bring isolated
pockets of critical fire weather conditions Thursday afternoon,
but coverage is looking increasingly limited. As the ridge moves
eastward Friday, monsoon moisture will move into the area from the
south, remaining in place through early next week. This will
bring increased potential for wetting rainfall, improved RH
values, but also the potential of storms that could produce heavy
rain that could lead to flash flooding.

&&

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

$$

PUBLIC...Traphagan
AVIATION...Cunningham
FIRE WEATHER...Cunningham

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