Wilson, Utah Weather Forecast Discussion

971
FXUS65 KSLC 242148
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
348 PM MDT Wed Sep 24 2025
.SYNOPSIS...Moisture increases across southwest Utah on Thursday.
After a drier day on Friday, moisture will once again bring a threat
of thunderstorms to southern Utah Saturday, and eastern Utah Sunday.
&&
.SHORT TERM (THROUGH 12Z FRIDAY)...The large-scale pattern this
afternoon consists of an omega block with Utah underneath the high
pressure while a cutoff low remains upstream off the central
California coast. Dry conditions are in place over Utah presently,
with PWATs around 0.4 inches across the area and barely a cloud in
the sky.
The upstream low will slowly shift inland tonight into tomorrow,
aided by a little nudge from a northern stream shortwave trough
crossing into the PacNW. As the low approaches, southerly flow will
increase which will draw in moisture currently present over SoCal
and southwest AZ. This increased moisture will bring showers and
thunderstorms to the area tomorrow. HREF ensemble mean PWATs
increase to around 0.7-0.8 inches across much of southwest Utah by
00z tomorrow evening, and over 1 inch in lower Washington County.
Rainfall potential will be limited a bit initially by dry low levels
and relatively fast storm movement. However, heading towards the
evening hours, the HREF does have dewpoints increasing pretty
quickly. As such, there is a heavy rain potential with a possibility
for flash flooding if a stronger storm develops over prone area, but
generally for only a few hours in the late afternoon through mid-
evening hours. WPC does have a Marginal risk in its Excessive
Rainfall Outlook for southwest Utah, which seems reasonable.
Overnight, the moisture will spread farther north and east and
showers will follow, although they will be weakening through that
time.
.LONG TERM (After 12Z/6AM Friday)...The period starts with a closed
low slowly tracking across the desert southwest. This will bring
periods of showers and afternoon convection, with the best chances
across the southern half of Utah, Friday through Sunday. As this low
moves to the east a PNW trough begins to push inland. A majority of
the ensemble members bring this trough through the area, along with
some widespread stratiform precipitation for northern Utah and SW
Wyoming, Tuesday or Wednesday of next week. Expect temperatures to
gradually fall with the passage of this trough.
The aforementioned closed low will be centered over southern
California by Friday. This will result in some light easterly flow
aloft for southern Utah, but some slightly drier air advects into
the area along with weaker instability. Hence, Friday could see a
lull in activity across the southern half of Utah. Areas favored in
easterly upslope flow could see some terrain driven convection on
Friday, but these showers will be pulse-like in nature given the
limited amount of shear to sustain prolonged updrafts.
By Saturday this low shifts slightly further east with better shear
and CAPE profiles along with increasing moisture. This will help to
increase convective activity across the southern half of Utah.
Median PWAT values across southern Utah increase to ~1.00" which
would fall close to the 95th-97th percentile for this time of year.
Flash flooding will be possible, particularly across flood prone
areas such as slick rock, burn scars, dry washes, and slot canyons.
By Sunday this closed low starts to phase back into the mean flow
and shift to the northeast a bit more quickly. As a result, expect
more convective activity to shift into eastern and portions of
northern Utah/SW Wyoming.
Into early next week a more robust trough pushing into the PNW will
increase southerly flow ahead of a weakening baroclinic zone. With
moisture in place along with upper level diffluence ahead of this
approaching trough, widespread precipitation is possible, especially
across northern Utah by Tuesday or Wednesday. Currently, ~82% of
members have this trough pushing through the area bringing some
amount of precipitation, whereas the other 18% keep this trough axis
offshore with mostly dry conditions. Timing of this trough also
varies a bit amongst the guidance with the faster solutions bringing
a cold front through the area as early as late Monday and others as
late as Wednesday.
&&
.AVIATION...KSLC...VFR conditions will persist at KSLC throughout
the duration of the TAF period. West-northwest winds will persist
through around 04z before becoming east-southeast following the
typical diurnal cycle.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will exist
across all terminals through the TAF period. Gusts across all sites
will generally subside around 02-04z following the typical diurnal
cycle.
&&
.FIRE WEATHER...Moisture will return to the area tomorrow as
southerly flow increases ahead of an approaching low pressure
system. This will bring showers and thunderstorms mainly to
southwest Utah tomorrow. Storms may initially be high-based, but
should trend wetter by late afternoon or early evening as surface
dewpoints and thus relative humidities quickly increase. Showers are
expected to spread farther north and east overnight while gradually
weakening. On Friday, the low pressure system dives farther south
towards southwest California, cutting off the moisture tap. However,
lingering moisture in place will likely bring another round of
showers and thunderstorms to the area, a mixture of dry and wet
storms which will remain mostly terrain- based. The low pressure
system will then lift north again over the weekend before ejecting
across the Four Corners area Sunday night. Moisture and associated
precipitation will spread back into Utah during this time, bringing
an increasing coverage of showers and thunderstorms and a better
chance of wetting rain. During the early part of next week, a
deepening trough is expected to bring increasing southerly winds to
the area ahead of a midweek cold front, although some uncertainty
remains regarding its strength and timing.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
Cheng/Mahan/Worster
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

NWS SLC Office Area Forecast Discussion