933
FXUS65 KSLC 190433
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1033 PM MDT Tue Aug 18 2026

.KEY MESSAGES...

- Building high pressure will bring a steady warming trend in
  temperatures through Thursday as conditions dry.

- 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...High pressure centered over western AZ tonight
through Wednesday will maintain an dry west-northwest flow over
UT. Latest analysis shows around 0.8-0.9 inches of PWAT across
the area. This should be enough to result in isolated to widely
scattered diurnal and mostly terrain-based showers and
thunderstorms.

The high pressure will gradually shift east towards CO/NM by
Friday, and a bit farther east for the weekend. This will bring a
gradual return of monsoonal moisture to the area, with showers
and thunderstorms increasing over the mountains and southern Utah
Thursday before becoming more widespread over the forecast area
Friday through at least the early part of next week. With the
increased coverage of thunderstorms and arrival of deeper
moisture coupled with added dynamics from a series of weak
disturbances crossing the area, the threat of flash flooding will
increase during this timeframe. A Marginal Risk of Excessive
Rainfall begins as soon as Thursday across portions southern Utah
and will be more widespread across the area by Saturday.

With the arrival of the deeper moisture, temperatures will trend
downward towards the end of the week into next week. Until then,
however, temperatures will remain on the warm side, with highs
around 5-10 degrees above normal. The NBM currently has a 25-30%
chance of SLC reaching 100F Thursday-Friday. However, with the
warm bias commonly exhibited locally by the NBM in the warm
season, suspect that the chance of reaching 100F is much higher,
especially on Thursday, so have adjusted temperatures to reflect
this thinking. HeatRisk also falls into the Red (Major) category
in many valley areas on Thursday, but the increased threat of
heat related illness will be mitigated due to overall acclimation
during the season.

&&

.AVIATION...KSLC...There is low confidence in wind direction
overnight; although southeasterly is likely to be the dominant
direction, there is a chance 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...Winds will remain fairly light
and terrain-driven overnight, with VFR conditions prevailing.
Isolated thunderstorms will redevelop Wednesday afternoon across
primarily eastern Utah with chances for gusty outflow winds.

&&

.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...Cheng
AVIATION...Cunningham
FIRE WEATHER...Traphagan

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