683
FXUS65 KSLC 192131
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
331 PM MDT Tue Aug 19 2025

.SYNOPSIS...High pressure will bring warm and mostly dry
conditions to the region through Wednesday. A monsoon surge will
bring moisture into the area for the latter part of the week and
into next week.

&&

.SHORT TERM (THROUGH 12Z THURSDAY)...High pressure remains in
place near the Four Corners region through midweek. Dry conditions
will yield to increasing midlevel moisture tomorrow into
Thursday. Some higher PWATs of 0.5-0.6 inches are currently
creeping into portions of western Utah. Moisture will continue to
gradually increase into this area tomorrow while also spreading
into southern Utah. This will remain mostly midlevel moisture
tomorrow, so isolated high-based showers with a few thunderstorms
producing gusty microburst winds will will be possible tomorrow
afternoon and evening. Greatest chance will be across northwest
Utah and over the southern and central mountains. Otherwise,
temperatures will remain hot, with afternoon highs across some
valleys, including along the Wasatch Front, pushing the 100 degree
mark once again tomorrow.

.LONG TERM (AFTER 12Z THURSDAY), ISSUED AT 247 AM TUESDAY...
By Thursday, deep moisture advection will continue and storms
will become more widespread across the state. Thursday`s
convection will likely be a mix of wet and dry thunderstorms as
the column moistens...or in reality for most...trend toward
actually seeing precipitation at the surface. The Weather
Prediction Center has outlooked portions of southern Utah in a
marginal risk (at least 5% chance) for flash flood guidance to be
exceeded across southern Utah Thursday afternoon.

Even with the moisture increasing across southern Utah,
temperatures will be in the 105-108 range across lower Washington
County and Zion National Park Thursday, and closer to 102 to 105
for lower portions of Glen Canyon National Rec Area. Overnight
lows will creep up to near to above 80F Thursday morning and
Friday morning. In coordination with WFO Las Vegas, issued an
Extreme Heat Watch for both Zion and lower Washington County for
Thursday...and this threat may extend into Friday. Held off on
Glen Canyon after coordination with WFO Flagstaff as confidence
isn`t quite as high to warrant issuance at this time.

By Friday, PW values will meet or exceed the 90th percentile
across the bulk of the region, and exceeding 200% of normal by
Saturday. With a persistent monsoon circulation in place through
at least early next week, anticipate a daily increased threat of
flash flooding through the period. After an extended period of no
measurable precipitation across large portions of the state (KSLC
hasn`t seen measurable precipitation since July 4), the rain will
be a welcome relief to high evaporative demand across the state.

&&

.AVIATION...KSLC...VFR conditions will persist for the KSLC terminal
through the period. Dry conditions and clear skies will continue
with light and diurnally driven winds.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will persist
for the airspace through the period. Dry conditions and clear skies
will continue with light and diurnally driven winds.

&&

.FIRE WEATHER...High pressure over the area will continue to bring
warm and mostly dry conditions over the area through Wednesday.
Increasing moisture for the second half of the week and into next
week will then bring an increasing threat of showers and
thunderstorms to the area. Isolated high-based showers and
thunderstorms will be possible as early as Wednesday, with gusty
microburst winds the main threat. Then, expect a gradual
transition to scattered to numerous coverage and mainly wet
thunderstorms by the weekend and into next week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Extreme Heat Watch from Thursday afternoon through Friday
     evening for UTZ123-124.

WY...None.
&&

$$

Cheng/Kruse/Mahan

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