079
FXUS65 KSLC 262321
AFDSLC

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

.KEY MESSAGES, Issued 132 PM MDT Sat Sep 26 2026...


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

- An upper-level disturbance moving across the Desert Southwest
  will draw deep tropical moisture from Hurricane 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, Issued 132 PM MDT Sat Sep 26 2026...
Utah and southwest Wyoming remains under generally
dry southwest flow today behind a transient ridge, keeping
convective chances at bay areawide. More active weather returns
on Sunday as an anomalous upper-level low begins to dig southward
along the west coast. As southerly flow increases aloft ahead of
this system, gusty winds are expected to develop across the
western half of Utah, with widespread gusts 25-30 mph. Mid-level
moisture will begin to draw up and into the region on Sunday as
well, yielding the development of widely scattered showers and
thunderstorms Sunday afternoon and evening, with greatest coverage
favored along and east of the topographic spine of Utah. Main
threat with these storms include gusty and erratic outflow winds,
with gusts in excess of 40 mph possible. Convective activity will
taper off overnight, though some isolated showers may linger over
the higher terrain into Monday morning.

Models are in good agreement that the aforementioned upper-level
low will eject eastward across the Desert Southwest on Monday,
bringing ample instability to the region as the associated vort
max traverses the region late Monday into early Tuesday. This
system will draw even deeper moisture into the region as it taps
into the reserves of Hurricane Odalys and Polo as they spin off
the coast of the Baja Peninsula. Ensembles show strong agreement
in this influx of tropical moisture resulting in widespread
precipitation across most of the region on Monday. They also have
a strong consensus that deepest moisture will be favored across
southeast Utah given the track of the upper-level low. However,
like many setups where tropical systems are involved, a good
amount of uncertainty still exists regarding the exact impacts
this precipitation will bring to our area. Previous model runs
favored a heavy rainfall and associated flash flood risk across
southeast Utah on Monday afternoon. However, recent runs show
more stratiform rain across southeast Utah due to considerable
cloud cover, with a favorable environment for heavy rainfall
across southwest Utah on Monday afternoon. Which solution comes to
fruition will be heavily dependent on the track of both the
tropical systems and the upper-level low. Regardless, expect
widespread wetting rains across central and southern Utah, with
the 25th percentile amounts between Monday and Tuesday between
0.5-1.00" across much of the region. Upper-end scenarios bring as
much as 1.25-1.5" of rain to much of central and southern Utah.

As the upper-level low continues to traverse into Arizona on
Tuesday, ample instability and moisture will exist across far
southern Utah on Tuesday for additional convective activity to
redevelop during the afternoon hours. A drier airmass quickly
fills in across the region on Wednesday, cutting off any lingering
activity across southern Utah by Wednesday morning. This dry
airmass will prevail through the remainder of the work week as
high pressure develops across the west, keeping conditions
seasonable and benign through this period.


&&

.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...Whitlam
AVIATION...Warthen
FIRE WEATHER...Whitlam

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