Severe Thunderstorm Warning 33, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
356 PM MDT Sun Aug 24 2025

.SYNOPSIS...Anomalous moisture will remain in place across Utah
and southwest Wyoming through the next several days, bringing
daily chances for showers and thunderstorms. The biggest risks
associated with these storms will be heavy rainfall/ flash
flooding, as well as gusty outflow winds and frequent lightning.
From Friday forward, conditions are expected to dry with shower
and thunderstorm coverage becoming more isolated by the weekend.

&&

.SHORT TERM (Through 12Z/6AM Tuesday)...Afternoon satellite and
radar trends have shown an area of broad subsidence across
northern Utah, leading to overall muted convective activity while
areas in central and southern Utah have maintained showers and
thunderstorms through much of the day. This convective activity
across southern and central Utah is expected to continued through
the remainder of the daylight hours, bringing a fairly widespread
threat of flash flooding, especially within dry washes, slickrock
areas, and recent burn scars. Across northern Utah, anticipate an
uptick in convective activity through the remainder of the
afternoon and early evening as conditions gradually destabilize.
A shortwave disturbance across central NV looks to eject eastward
through this evening, and may act to maintain convective activity
across northern Utah/ southwest Wyoming through the overnight
hours, though the overall threat of flash flooding will be
limited.

Moving into Monday, atmospheric moisture is expected to subtly
increase across the region as a swath of anomalous PWAT begins to
pivot north and east. In general, expect another day of fairly
similar afternoon conditions. Any showers and thunderstorms, not
already ongoing in the early morning from the aforementioned
shortwave, are expected to begin forming over the high terrain
features across Utah and southwest Wyoming during the late
morning/ early afternoon hours. Developing cells will have a
tendency to drift north and east off the high terrain, bringing a
risk of heavy rainfall, small hail, gusty outflow winds, and
frequent lightning.

Another ejecting shortwave trough moving through the Great Basin
is anticipated to progress over the eastern Great Basin region
through the late evening and overnight hours. As such, enhanced
atmospheric lift combined with the moisture and instability
already in place will help to keep widely scattered showers and
thunderstorms maintained through the overnight hours into Tuesday
morning.

.LONG TERM (After 12Z/6AM Tuesday), Issued 335 AM MDT...
By early Tuesday the mid level
ridge axis will be centered across the southern Plains, allowing for
a deep layer southerly flow extending from the Baja region through
the Desert Southwest and into the eastern Great Basin. This flow
will continue to maintain a fairly robust monsoon airmass across the
forecast area with widespread PW values in excess of 1" and surface
dew points in the 50s across low-mid elevations. Model guidance has
been indicating a weak wave within this flow will lift through the
region during the day Tuesday, enhancing lift and resulting in
fairly widespread precipitation across the forecast area. How much
surface heating and subsequently the degree of instability available
Tuesday will determine the heavy rain threat, but with the amount of
available moisture any thunderstorms which do develop will be
capable of heavy rainfall Tuesday afternoon and evening.

By Wednesday, in the wake of this wave, low level flow will veer to
westerly allowing for the beginning of a drying trend. As is often
the case as the airmass being to dry, increased solar heating
coupled with ample lingering moisture may actually result in a bigger
heavy rain/flash flood day Wednesday afternoon and evening.

Owing to widespread cloud cover and precipitation daytime
temperatures Tuesday and Wednesday will run 7-10F below climo,
potentially struggling to reach the low 80s along the Wasatch Front
as well as most western and central valleys, while the St
George/Zion Canyon area remains in the low 90s.

A more westerly flow will become established for the latter portion
of the upcoming week, which will work to gradually erode the
monsoonal airmass. Lingering moisture will maintain showers and
thunderstorms, however coverage will decrease Thursday into Friday.
With the decrease in moisture temperatures are forecast to trend
slightly upward heading into next weekend.

This drying trend will continue through the end of the week as mid
level ridging begins to amplify across the Great Basin. This will
allow for a gradual warming trend heading into the upcoming holiday
weekend, with lingering moisture maintaining a reduced chance of
mainly terrain driven convection.

&&

.AVIATION...KSLC...Northerly flow is expected to persist through
the early evening, switching to diurnal southeast winds around
04z. If current showers moving through the west desert persist,
these might impact the terminal with gusty and erratic winds
around 01z, with a smaller chance of additional vicinity showers
between 04-08z.There is a 10 percent chance of a thunderstorm
producing lightning and gusty winds with these showers.

.REST OF UTAH AND SOUTHWEST WYOMING...For the southern
terminals, afternoon showers and thunderstorms producing gusty
outflow winds, lightning, and brief MVFR visibility within heavier
rainfall are expected to diminish around sunset. Northern terminals
may see a few bands of showers move through the region after about
01z with only a slight chance of vicinity thunderstorms.
Otherwise VFR conditions with terrain driven winds can be expected.

&&

.FIRE WEATHER...Moderated fire weather conditions are expected
across the entirety of Utah through at least Wednesday as
monsoonal moisture remains in place over the eastern Great Basin
region. Each day through Wednesday/ Thursday, afternoon showers
and thunderstorms are expected, bringing higher chances of wetting
rains. If an individual area does not receive wetting rains,
afternoon humidity will be significantly moderated as we peak in
moisture on Monday and Tuesday. Afternoon minimum humidity values
are expected to be between 25 and 40 percent for a majority of
Utah through at least Thursday.

From Friday forward, anticipate an overall drying of the
environment across Utah as a dry westerly flow begins to work into
the region. Alongside this drying trend, anticipate temperatures
warming through this period as well. That said, daytime high
temperatures are still expected to remain below climatological
normals for this time of year. With any lingering moisture in the
lower levels, isolated showers and thunderstorms are anticipated
to develop over the high terrain across the state of Utah, with
a chance for dry lightning, though coverage of any dry lightning
is expected to be fairly minimal. While daytime minimum humidity is
expected to drop back into the 15-25 percent range, overnight
humidity recovery is still expected to be fair to good as values
recover to between 45 and 55 percent.

&&

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

SHORT TERM...Webber
LONG TERM...Seaman
AVIATION...Verzella
FIRE WEATHER...Webber

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

Special Weather Statement
National Weather Service Salt Lake City UT
345 PM MDT Sun Aug 24 2025

UTZ125-126-242215-
Upper Sevier River Valleys UT-Southern Mountains UT-
345 PM MDT Sun Aug 24 2025

...A strong thunderstorm will impact portions of south central Piute
and northwestern Garfield Counties through 415 PM MDT
...

At 345 PM MDT, Doppler radar was tracking a strong thunderstorm near
Junction, moving northeast at 15 mph.

HAZARD...Half inch hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to outdoor objects is possible.

Locations impacted include...
Junction, Circleville, and Kingston.

This includes US Route 89 between mile markers 153 and 164.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3806 11224 3814 11237 3827 11228 3816 11206
TIME...MOT...LOC 2145Z 216DEG 12KT 3815 11227

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...<40 MPH

JW

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