Snowbird

000
FXUS65 KSLC 060402
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1002 PM MDT Sat Sep 5 2026

.KEY MESSAGES...

- Modestly breezy conditions with gusts around 25-40 mph persist
  through Sunday afternoon, primarily west of the I-15 corridor.

- Flash flooding risk increases Sunday, especially from southwest
  to central Utah as tropical moisture increases. A Flood Watch is
  in effect accordingly.

- Isolated severe storms capable of strong to severe wind gusts
  and small hail will be possible across portions of northwest
  Utah Sunday afternoon.

- Drier conditions return for early next week, with uncertainty
  noted on potential for more unsettled conditions from midweek
  onward.

&&

.DISCUSSION...Evening water vapor analysis shows a broad trough 
extending southward through the PacNW with deep southerly flow 
noted locally overhead. While a plume of tropical moisture is 
evident lifting northward through the Desert Southwest, most 
locations across Utah and southwest Wyoming have remained largely 
clear, if not sunny. The southwesterly flow has resulted in some 
modestly breezy conditions around the area, but temperatures have 
remained seasonably mild for early September.

The moisture plume will continue to advance northward overnight, 
beginning to encroach into southern Utah with associated shower 
activity closer to sunrise. This moisture will then continue to 
overspread the majority of the forecast region as the day 
progresses, with PWAT anomalies rising to around 150-200% of 
climatological normal. Concurrently, will see flow overhead 
increase with an embedded shortwave shifting through, providing 
increased synoptic forcing for ascent. While mean instability is 
only progged to increase to around 150-300 J/kg in the afternoon,
and will to a degree be predicated on cloud cover and degree of 
stratiform rain, anticipate the enhanced synoptic forcing will 
allow pockets of embedded thunderstorms to develop. Models suggest
any such activity will have potential for rain rates in the 0.5" 
to 1.0" per hour range, and with the deep moisture, would expect 
even showers will be capable of fairly efficient rainfall 
production. Additionally, continued moisture advection in the 
southwesterly flow may help bring redeveloping and/or training 
storm activity.

Given the setup, Sunday will see potential for excessive rainfall
and instances of flash flooding. The WPC Excessive Rainfall 
Outlook includes southwestern to central Utah within a "Slight 
Risk" (level 2 of 4) of excessive rainfall, and the majority of 
the remainder of the forecast region in a "Marginal Risk" (level 1
of 4). General model consensus supports the highest focus of 
activity from southwest Utah through central Utah, especially 
along the high terrain and nearby areas. For now, have maintained 
the ongoing Flood Watch for this general area, though a shift in 
the plume by even 20 miles or so may necessitate expansion of the 
watch area. Will have to monitor trends accordingly. Per usual, 
the highest threat will be for typically rain sensitive locations 
such as recent burn scars, slot canyons, typically dry washes, and
slickrock areas. Those with recreation plans in such areas should
stay weather aware and consider alternatives.

Aside from the flood threat, models also support potential for 
more isolated convection forming on the periphery of this plume, 
particularly in portions of northwest Utah. While also dependent 
to an extent on the degree of destabilization, the enhanced flow 
aloft will result strong deep layer shear in excess of 40 kts or 
so. This area will also be nearer a slowly approaching front from 
the larger PacNW trough. While conditional, any storms that can 
become better organized will have at least some threat of strong 
to severe wind gusts and small hail.

Precipitation will gradually diminish overnight moving into 
Monday morning as the moisture plume exits and the deep PacNW 
trough's evolution will allow a drier and more zonal flow to 
develop. The associated cold front will also progress as far south
as central Utah in vicinity of the I-70 corridor or so, bringing 
cooler temperatures behind it. Afternoon highs behind the front 
Monday will tend to run around 5-10 degrees below normal, with 
temperatures ahead of it near to slightly below normal. The front 
will begin to wash out quickly, with temperatures for Tuesday 
moderating back upwards nearer to typical levels.

Uncertainty increases from Wednesday onward with models diverging
on the exact pattern evolution. There is support that mid to 
upper level ridging will be centered somewhere in the southwest 
CONUS, but with varying placements. If centered more atop the Four
Corners region the local area will see better potential for 
moisture returning, with decreasing favorability the further to 
the west it ends up. Around 30% of ensembles support a more marked
moisture surge and higher precipitation potential, around 30% 
have a more muted moisture return and likely more isolated 
precipitation potential, and the remaining 40% remain on the drier
side of the envelope.

&&

.AVIATION, Issued 701 PM MDT Sat Sep 5 2026... 

KSLC...Southerly winds remain generally light overnight into Sunday 
morning, gradually increasing after 14z. Winds further increase 
around 20z, with gusts exceeding 25 kts developing through the 
evening. An influx of tropical moisture into northern Utah will 
result in gradually increasing cloud cover and lowering CIGS Sunday 
morning. Steady rainfall is expected to move into the vicinity of 
the terminal after 20z, with potential to produce brief MVFR CIGS 
through the evening.

REST OF UTAH AND SOUTHWEST WYOMING...Gusty southerly winds across 
the airspace taper overnight before increasing gradually after 
roughly 13-16z. Wind gusts in excess of 25 kts are expected to 
develop through the afternoon for most regional terminals. An influx 
of tropical moisture into the region will result in gradually 
increasing cloud cover overnight into Sunday morning, with lowering 
CIGS as widespread rain moves in from the south through the day. 
Showers and thunderstorms taper off by early Monday morning. 

&&

.FIRE WEATHER, Issued 208 PM MDT Sat Sep 5 2026...
Moisture will continue to gradually increase into
sunday as southwesterly flow pushes moisture further north.
This afternoon, expect locally critical fire weather conditions 
primarily across the West Desert and Great Salt Lake Desert where 
humidities have been observed dropping below 15%. Additionally, 
strong wind gusts across areas primarily west of I-15 will range 
from 30-45mph each afternoon into Sunday. 

On Sunday, a stronger push of moisture arrives to Utah with 
widespread showers and thunderstorms across the state, though 
primarily across central and southern Utah. The highest rainfall 
totals are expected across higher terrain of central and southern 
Utah, though lower elevation areas further east may see higher 
isolated totals from stronger storms. For lower lying areas west of 
I-15, generally a trace or less of precipitation is expected on 
Sunday. A drying trend is expected to develop Monday and Tuesday 
with more precipitation expected after midweek next week across at 
least southern and central Utah.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch from 9 AM MDT Sunday through Sunday evening for 
     UTZ113-114-116>120-122-124>128.

WY...None.
&&

$$

PUBLIC...Warthen
AVIATION...Whitlam
FIRE WEATHER...Worster

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