075
FXUS65 KSLC 270438
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1038 PM MDT Sat Sep 26 2026

.KEY MESSAGES...

- Increasing moisture aloft ahead of an approaching system will
  result in scattered showers and thunderstorms across southwest
  Wyoming, the Utah mountains, and the eastern half of Utah on
  Sunday.

- An upper-level disturbance moving across the Desert Southwest
  will draw deep tropical moisture from Hurricanes Odalys and
  Polo into the region Monday into Tuesday, bringing an increased
  risk for flash flooding across portions of southern and eastern
  Utah.

- Drier, more seasonable conditions develop mid-week and persist
  through at least Friday.

&&

.DISCUSSION...A dry southwesterly flow remains in place over Utah
this evening. Upstream, an upper trough is strengthening off the
PacNW coast. Meanwhile, Hurricanes Odalys and Polo continue to
spin in the eastern Pacific.

The upstream trough will carve south towards the northern/central
California coast on Sunday, with southwest flow continuing over
Utah. Meanwhile, a weak vort lobe originating near Hurricane
Odalys will become absorbed into the southwesterlies and lift
across Utah during the afternoon. This weak disturbance will bring
increased moisture and isolated to scattered showers and
thunderstorms to Utah by Sunday afternoon, generally focused over
and near the spine of Utah.

As the trough develops into a closed low over southern California
and far southern Nevada on Monday, Hurricane Polo will track
northeast, moving into Baja California. Moisture from the
hurricane will become ingested into the southwesterly flow ahead
of the closed low and increase into southern Utah. This will
continue to bring the potential for widespread and locally heavy
rain, especially across southern and eastern Utah as the closed
low crosses from California into Arizona Monday through Tuesday.

Model QPF continues to creep up for the Monday-Tuesday timeframe,
especially notable on the lower end of the probabilistic spectrum
(NBM 25th percentile values now in excess of 0.6 inches for the
bulk of south-central and southeast Utah), which increases
confidence in wet conditions. A good portion of south-central
through southeast Utah has a 60-70% chance of exceeding 1 inch
Monday through Tuesday, highest along the Arizona border.
Precipitation amounts will decrease farther north and east into
Utah, with east-central Utah having a 60-70% chance of exceeding
0.5 inches, and areas farther north and east with a 30% chance or
less.

The heavy rain will bring an increased risk of flooding/flash
flooding to the area. The WPC Excessive Rainfall Outlook now has
a Moderate Risk across portions of southern Utah, and the Slight
Risk now extends into central and portions of northeast Utah.
Although model instability is increasing, especially across
southwest Utah, precipitation may well end up as largely
stratiform with embedded convective elements, and the strength and
coverage of these convective elements will most likely determine
the extent of any significant flash flooding.

Cooler temperatures will spread into the area Monday and Tuesday,
with afternoon maxes falling to around 4-10 degrees below normal
and largely failing to rise above the low to mid 70s in most
valleys. Temperatures will slowly rebound midweek as the storm
system exits the area. There is still some model spread with
regards to the large-scale pattern for the latter part of the
week. Some models have been trying to bring a trough back into the
area, but based on cluster analysis of global ensembles, it
appears that any trough may end up being relatively weak.

&&

.AVIATION...
KSLC...Southerly winds are expected to gradually increase overnight,
with occasional gusts to around 25 kts beginning after sunrise and
carrying on through the day. Southerly winds are favored to persist.
VFR cloud cover will also gradually increase as moisture continues
to move into the area. Shower chances will increase Sunday night
into Monday morning, particularly after around 09Z or so.

REST OF UTAH AND SOUTHWEST WYOMING...Moisture associated with an
approaching trough and remnant tropical system will increase through
the TAF period. The enhanced south to southwesterly flow will favor
such a direction at most area terminals, with gusts 20-30 kts
developing after sunrise and on through the day. VFR cloud cover
will also increase. There is around a 20-30% chance of showers and
thunderstorms developing Sunday afternoon, primarily along and just
east of Utah`s high terrain and into southwest Wyoming.

&&

.FIRE WEATHER, Issued 132 PM MDT Sat Sep 26 2026...
Increasing southerly flow aloft through the
remainder of the weekend will result in gusty afternoon winds
developing across the western portion of the state through Sunday,
with widespread gusts 25-30 mph. While conditions remain dry
today, especially across portions of southern Utah where daytime
RH values dip to near-critical, improving overnight recoveries
tonight will limit the fire weather risk overall. Moisture
associated with two tropical systems in the Eastern Pacific will
increase steadily on Sunday, with best moisture availability
focused across southern and eastern Utah. This will result in
scattered showers and thunderstorms developing across these areas
on Sunday afternoon, with the main threat being gusty and erratic
outflow winds as lower levels remain relatively dry. Deep moisture
overspreads the region Monday into Tuesday; concurrently, an
upper-level wave traversing the western US will result in ample
instability developing across southern and eastern Utah on Monday
afternoon. This increasing instability will interact with deep
tropical moisture, resulting in more widespread showers and
thunderstorms capable of producing heavy rainfall and better
chances for widespread wetting rains through Tuesday morning.

&&

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

$$

PUBLIC...Cheng
AVIATION...Warthen
FIRE WEATHER...Whitlam

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