Flood Watch 2, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
413 AM MDT Tue Aug 26 2025

.SYNOPSIS...An ongoing monsoon surge will bring a heightened
threat of heavy rain with any thunderstorms across the region
through Tuesday. By Wednesday, drier air will begin to shift
northward into southern Utah, reaching the remainder of the state
by Thursday. Drier conditions are expected to continue Friday into
the weekend.

&&

.SHORT TERM (THROUGH 12Z THURSDAY)...High pressure is now centered
over central New Mexico, with a south to southwesterly flow aloft
over Utah. A weather disturbance is noted moving into southwest
Utah currently, and is progged to continue lifting north through
the day. Areas of 1 inch or greater PWAT are noted across
northwest Utah and far southern Utah this morning, and PWATs are
expected to peak today, with values of 1.2 inches or greater in
many valleys.

An area of widespread showers with embedded thunderstorms are
moving into southern Utah this morning along the leading edge of
the aforementioned weather disturbance, while more isolated to
widely scattered shower and thunderstorm activity is noted
elsewhere. As the disturbance lifts north, expect the widespread
showers to follow, reaching central Utah by late morning and
northern Utah this afternoon. The strongest storms and heaviest
rain are expected across northern and central Utah, coincident
with the position of the weather disturbance during peak daytime
heating. However, given ample morning cloud cover, will see how
much instability this heating will actually help generate...it
could be a bit limited. Southern Utah, particularly southwest
Utah, may see convection suppressed behind the wave during the
afternoon, although some CAMs do show portions of south-central
and southeast Utah light up with convection this afternoon.
Tonight, expect some nocturnal showers and thunderstorms to
continue across northern Utah. This includes portions of the
Wasatch Front where some CAMs maintain some stronger storms.

Drier air will start so spread into the area tomorrow, beginning
with the south. However, given lingering low-level moisture along
with decreased morning cloud cover aiding afternoon instability,
expect to see scattered to numerous showers and thunderstorms,
some of which will continue to be strong and produce heavy rain.
Far southern Utah will see less coverage of storms due to drier
air, but central and northern Utah will likely remain quite
active. Otherwise, the clouds and moisture given the active
weather will maintain cooler afternoon max temperatures across
Utah both today and tomorrow, between 5-15 degrees below normal
today and 6-10 degrees below tomorrow.

.LONG TERM (After 12Z/6AM Thursday)...Mid level ridging will slowly
re-establish itself across the region for the latter portion of the
week through the upcoming holiday weekend. With rising heights the
airmass will continue to slowly dry each day. Temperatures will be
slow to respond initially, remaining 5-8F below climo through Friday
before slowly trending warming through the weekend.

Sufficient moisture will remain across the forecast area to support
mainly afternoon and evening showers and thunderstorms Thursday.
These will be most numerous across northern and central Utah where
locally heavy rain will remain possible with stronger updrafts,
while drier and more stable air will limit convective coverage
across the south. Lingering moisture will again support showers and
thunderstorms Friday, with coverage and intensity waning due to this
slow drying trend. By Saturday lingering convection will remain
largely isolated and confined to the higher terrain.

&&

.AVIATION...KSLC...Predominant VFR conditions with southeasterly
winds are expected at the terminal this morning. There is a 20-30%
chance of showers or thunderstorms impacting the terminal through
18Z, with the main threat being lightning and gusty outflow winds to
25 kts. After 18Z, showers and thunderstorms will become widespread
around the area through the afternoon with temporary visibility
reductions into the MVFR range within heavier rainfall. The most
likely window for thunderstorms will be during the 18-22Z timeframe.
The threat for occasional showers and thunderstorms impacting the
terminal will persist through the evening and overnight hours.

.REST OF UTAH AND SOUTHWEST WYOMING...A surge of monsoon moisture
will bring widespread showers and thunderstorms to the region today.
These will be most numerous across southern Utah this morning, then
spread into northern Utah and southwest Wyoming this afternoon.
Lightning, gusty outflow winds, and temporary visibility reductions
in the MVFR or even IFR range within heavy rain will be possible at
all terminals through this afternoon. Additional showers and
thunderstorms will linger across northern Utah and southwest Wyoming
into the evening and overnight hours.

&&

.FIRE WEATHER...A monsoonal pattern continues with moisture peaking
over the area today. A weather disturbance lifting north across
western Utah will bring more widespread precipitation to the area
today, focusing on southern and central Utah during the morning
and early afternoon, then more so across central and northern
Utah through the remainder of the afternoon and evening. Wetting
rain chances will be fairly high across most areas today. In
conjunction with the increased moisture, afternoon relative
humidities should see a more notable increase compared to the
previous few days.

Expect some showers and thunderstorms to continue tonight,
especially across northern Utah, some of which could be relatively
strong and maintain a potential for wetting rain. Tomorrow, the
airmass will start to dry a bit, especially across the far south.
However, lingering low-level moisture and potentially better
instability should allow for the development of showers and
thunderstorms, some of which may be strong and produce wetting
rain.

Coverage and intensity of showers and thunderstorms will then
gradually decrease Thursday and Friday and into the weekend as
drier air continues to spread into the area. Afternoon relative
humidities will lower back into the teens in many valleys over
the weekend.

&&

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

Cheng/Seaman

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