Alta

000
FXUS65 KSLC 111119
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
519 AM MDT Fri Sep 11 2026

.KEY MESSAGES, Issued 1032 PM MDT Thu Sep 10 2026...


- A marginal risk (level 1/4) for excessive rainfall is in place 
  across portions of southern Utah Friday through Sunday.

- There is a ~50% chance the northern valleys will see wind gusts
  in excess of 45 mph for 3 or more hours Saturday evening into 
  late Saturday night ahead of a strong cold front.

&&

.DISCUSSION, Issued 1032 PM MDT Thu Sep 10 2026...
A weak shortwave crossing the region embedded in
quasi-zonal flow continues to shift across northern Nevada into 
northern Utah through the overnight hours. Mainly high-based 
showers are noted on radar moving into far western Utah. A few 
locations may see a period of light rain overnight, but widespread
rain is not expected. Given decoupling, don't expect much of a 
gusty, microburst wind threat with this high-based convection.

As broad troughing engulfs the Pacific Northwest, the upper level
ridge will continue to flatten, allowing for modest moisture
advection to shift into southern Utah Friday. The bulk of the CAMS
indicate that the highest threat of isolated to widely scattered
thunderstorms will be across southern and eastern Utah Friday
afternoon into Friday evening. Given the net moisture increase,
WPC has outlooked this area in a marginal risk for excessive
rainfall. This correlates well with conceptual models and
guidance. The flash flood potential product for the southern Utah
national park and rec areas has every location in a "possible" for
Friday. 

By Saturday, weak subsidence will likely suppress convection in
most locations, though isolated thunderstorms across far eastern
portions of the CWA including the Swell and Capitol Reef area will
represent a low end flash flood threat.  

As early as Saturday evening, another period of moisture advection
will shift into southern Utah ahead of a strong cold front. This
front continues to slow down in each iteration of guidance...now
looking to reach northwestern Utah after sunrise Sunday, reaching
southern Utah by Monday morning. This may provide another window
with enhanced moisture for another round of at least isolated to
widely scattered thunderstorms across southern and eastern Utah
ahead of the cold front.

As far as gusty winds ahead of the cold front, it will be a battle
between decoupling and a strong gradient whether northern valleys
will see advisory level winds Saturday evening/night into early 
Monday. NBM probs still suggest around a 50% chance wind advisory 
criteria will be met, but the later this cold front shifts, the 
less likely wind advisory criteria will be met.

Much cooler temperatures will build into the region by Monday.
Given the slower cold front timing, the cooldown Sunday isn't as
aggressive, around 10-15 degrees across northern Utah, with around
another 5 degrees of cooling by Monday.

Longer range, southern and eastern Utah is outlooked in a 
moderate risk for heavy precipitation between the 18th and 20th.
Something to keep an eye on...and an indication that an extended
period of dry conditions is the less likely outcome through the
next few weeks.  



&&

.AVIATION... 

KSLC...Increased cloud cover, isolated shower chances, and 
associated potential for gusty erratic outflow winds will persist 
into late Friday morning. Winds otherwise follow a normal diurnal 
pattern, most likely shifting NW ~17-19Z. Cloud cover will then 
decrease through the day, with diurnally typical winds and VFR 
conditions favored.

REST OF UTAH AND SOUTHWEST WYOMING...A weak grazing system will 
bring isolated shower chances to northern terminals through roughly 
late Friday morning, and isolated convection to southern terminals 
through Friday afternoon. Aside from the influence of precipitation, 
winds are expected to follow a diurnally typical pattern. VFR 
conditions are also anticipated to continue, with cloud cover 
trending downward as moisture with the system decreases.


&&

.FIRE WEATHER, Issued 228 AM MDT Fri Sep 11 2026...
A weak grazing system will continue to push a 
correspondingly weak boundary into northern Utah into Friday 
morning, bringing increased moisture, cloud cover, and isolated 
shower chances. Isolated convective redevelopment is then expected
across portions of southern Utah Friday afternoon.

Moving into the weekend, the next approaching system will bring 
increasing deep southwesterly flow. Winds will tend to increase, 
especially in unsheltered valley locations across western Utah, 
with daytime gusts around 25-40 mph. Models continue to fluctuate 
on timing of a cold frontal boundary with this system. In general,
and especially if during the day, southwest winds will increase 
and become maximized ahead of this frontal passage, with a briefer
period of gusty northwest winds likely following the front. 
Largely, this front is expected to by dry in nature with the best 
chance of precipitation noted across portions of eastern Utah 
where moisture is favored to be higher. An unsettled pattern will 
yield continued isolated to at times scattered convective chances 
along and east of Utah's high terrain through midweek. There is 
considerable uncertainty in if, and to what extent, tropical 
moisture may then combine with another system later in work week.

&&

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

$$

PUBLIC...
AVIATION...Warthen
FIRE WEATHER...Warthen

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