St. George, Utah 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

098
FXUS65 KSLC 052145
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
345 PM MDT Fri Sep 5 2025

.SYNOPSIS...Moist and unstable pattern to continue to support more
widespread shower and thunderstorm coverage through the weekend,
and an associated localized flash flood threat. Somewhat drier
conditions are expected to return by early next week.

&&

.SHORT TERM (Through 12Z/6AM Sunday)... Currently, observed PWATs
per SPC Mesoanalysis shows around 0.9-1.2" of water across
southwestern UT where storm development is expected to focus this
afternoon into the evening. However, coverage and overall extent
appear to possibly be more limited than initially thought as
midlevel heights are building quicker than anticipated across
southwestern UT. This may serve to inhibit vertical development of
storms resulting in shorter lived and less robust convection on a
larger scale. However, given the deep moist environment in place,
instances of isolated flash flooding remains possible this afternoon
into the evening across southern UT. The WPC currently has the
southern half of UT outlined in a Marginal Risk (1/4) for excessive
rainfall for the remainder of the day.

Storms should quickly diminish after sunset with a calmer evening
expected across the state. H5 heights continue to build through the
evening with perhaps an embedded shortwave lifting north across the
state which will serve to spark a complex of showers across northern
UT in the morning hours. Additionally, moisture is expected to surge
north yielding PWATs ranging from 0.8-1" across the majority of the
state with some locally higher PWATs possible. Upper flow begins to
shift to a more westerly component with multiple embedded shortwaves
traversing the state providing enough ascent to spark storms across
the majority of UT and southwest WY tomorrow afternoon. With deeper
moisture available CWA-wide, the WPC has outlined the entire
forecast area in a Marginal Risk (1/4) for excessive rainfall.

One limiting factor tomorrow may be mid-level height rises as
ridging continues to build in ahead of a trough just off the West
Coast. For the majority of the forecast area, MLCAPE values
generally hover around 500J/kg or less with some storms likely
struggling to mature as subsidence continues to build in throughout
the afternoon. However, Theta-rich air appears to push into
southwestern UT tomorrow afternoon with a plume of MLCAPE in excess
of 1000J/kg. In fact, ensemble guidance indicates that there is a 30-
60% chance that SBCAPE may exceed 1500J/kg across southwestern UT
with probabilities increasing with southwestern extent. If this
instability were to materialize, storms may struggle less across
southwestern UT compared to other parts of the forecast area and
pose more of a threat for flash flooding.  Regardless of
instability, more abundant moisture across the forecast area does
still pose a threat for flash-flooding in flood-prone areas and
across burn scars.

Ensemble guidance continues to support a pattern shift come Sunday
as troughing to our west continues to shift east with a tightening
pressure gradient across the area. Enhanced dry southwesterly flow
aloft will overspread the area gradually mixing out moisture across
the forecast area.

&&

.LONG TERM (After 12Z/6AM Sunday), Issued 356 AM MDT...
Ensembles continue to support a
longwave trough phasing into a closed low off the coast of
northern California on Sunday, introducing drier southwesterly
flow aloft. This pattern will allow monsoonal moisture to
gradually wane from west to east, resulting in less convective
activity on Sunday afternoon. Best coverage for afternoon showers
and thunderstorms will favor northeast Utah and southwest Wyoming
where monsoonal moisture will linger just a bit longer. Otherwise,
more isolated coverage is expected across the remainder of the
forecast area. With PWAT anomalies still in the 125 to 150 percent
of normal range, locally heavy rainfall will remain a threat for
any stronger cells that develop. Drier conditions throughout the
column may also support gusty and erratic outflow winds to 40 mph.

The aforementioned low begins to nudge inland into northern
California on Monday into Tuesday, resulting in limited convective
activity and breezy winds developing on Monday afternoon. The low
will continue to slowly meander eastward through Thursday, with
an associated upper-jet strengthening across the region through
this period. Gusty southwesterly winds are expected to develop
areawide each afternoon as a result, with strongest winds favored
on Tuesday and Wednesday across southern Utah, where gusts to
30-35 mph are possible. Winds remain elevated Thursday, before the
low ejects eastward out of our region Friday.

&&

.AVIATION...KSLC...VFR conditions are likely to prevail at the
terminal through valid TAF the period. Winds remain generally light
and diurnally driven, with northwesterly winds transitioning
southeasterly after 03z. Rain showers are expected to develop over
the general area Saturday morning into the early afternoon,
potentially as early as 14z, but the most likely timeframe for
showers and thunderstorms look to be 16-20z.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions expected
through the period for all regional terminals. Showers and
thunderstorms are expected to continue through this afternoon over
and near the higher terrain, drifting more into the eastern Utah
valleys and southwest Utah heading into this evening before
weakening. Storms that develop will be capable of producing locally
heavy rain and erratic winds, with potential to push CIGS into
MVFR/IFR levels under heavier cores through this evening. Some
nocturnal showers developing over the West Desert of Utah may bring
showers into Saturday morning for southern/central Wasatch Front
terminals.

&&

.FIRE WEATHER...The monsoonal moisture surge continues to surge
north tonight through tomorrow with another round of scattered
convection developing across the majority of the state with more
notable coverage across northern UT compared to previous days.
Storms are expected to be wetter tomorrow across southern UT as
deeper and higher quality moisture pushes in resulting in another
day of flash flooding concerns across rain-sensitive locations and
burn scars. Storms tomorrow have the potential to have gusty and
erratic winds with lightning across the forecast area. With this
moisture surge, excellent overnight recoveries are expected through
Sunday.

On Sunday, we will begin to see a drying trend as a system slowly
meanders towards the west coast. This is due to enhanced
southwesterly flow aloft which will serve to shut off the monsoonal
moisture push into UT. Additionally, this will increase sustained
wind speeds and wind gusts into next week which will serve to dry us
out even more through the middle of next week.

&&

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

$$

SHORT TERM...Worster
LONG TERM...Whitlam
AVIATION...Cheng
FIRE WEATHER...Worster

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