210
FXUS65 KSLC 060951
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
351 AM MDT Sat Sep 6 2025

.SYNOPSIS...Abundant moisture lingers another day, with increasing
coverage of widespread showers and thunderstorms expected
Saturday bringing a localized flash flood threat. A drying trend
sets in Sunday into the upcoming week, but some isolated to
scattered precipitation chances will remain.

&&

.SHORT TERM (Through 12Z/6AM Monday)...Analyzed PWAT values from
around 0.7" to 1.1" in combination with a subtle mid level wave
lifting through is resulting in continued nocturnal shower
activity this morning. Most of this activity is confined to a
spatially thin strip of precipitation curving from north of BCE on
into NV towards LKN. Limited instability has so far kept activity
a bit lighter and stratiform in nature, though on occasion have
observed a few lightning strikes. While nothing problematic is
currently noted, will have to keep an eye on things in case
something flares up a bit more or the motion allows for more of a
training band to develop.

Saturday looks to have potential to be another active day as
widespread lingering moisture yields PWAT anomalies around
140-180% of normal. A continued question is in regards to how the
ongoing nocturnal activity evolves. General CAM consensus lifts
this activity further into N UT and SW WY in the hours following
sunrise, while clearing out much of the SW quarter of UT or so.
Interestingly, despite lingering cloud cover associated with the
morning activity, CAMs seem to destabilize the area sufficiently
to yield increasing convective development early to mid afternoon.
At the same time, models are less aggressive on convective
development across SW UT despite the earlier clearing and better
destabilization. Potentially this is due in part to height rises
as the initial shortwave impulse continues to lift northeastward.
While that uncertainty may result in CAMs maybe not having a
perfect handle on Saturday`s convective evolution, especially in
regards to exact coverage/strength/timing, there should be enough
ingredients for scattered convective development across a large
portion of the area. With the abundant moisture, this activity
will once again have potential to result in a localized flash
flood threat with anything that drifts over a rain sensitive basin
(slot canyon, typically dry wash, slickrock area, recent burn
scar). As has been the case the past couple days, those with
recreating plans at such areas should consider alternatives and/or
remain weather aware. Coverage and strength of activity will wane
late Saturday evening into the overnight hours.

On Sunday a broad trough slowly churning towards the western US
coast will help maintain a drying southwesterly flow over the
area. Moisture will not completely scour out, in fact PWAT
anomalies remain around 100-140% of normal, so enough to work
with. Unlike previous days however there won`t be much in the way
of synoptic support offered, with if anything a somewhat weak mid
level ridge noted overhead instead. As such, thinking more
activity will end up terrain initiated, in turn with the higher
coverage of precipitation along/east of area high terrain, but
with lower coverage overall in comparison to prior days. As
generally typical, expect this activity to wane through the
evening hours on into the overnight.

.LONG TERM (After 12Z/6AM Monday)...There is really good model
agreement that a longwave trough will be positioned off the
Pacific coast near the California and Oregon border Monday. As
this system approaches, a ridge will slide east. The associated
monsoonal moisture will diminish throughout southwest Wyoming and
Utah. Meanwhile, southwest flow east of the trough axis will
enhance. Southwest wind gusts will range from 15-25 mph for
southwest Wyoming and southwest Utah.

Southwest flow will strengthen as the longwave trough slides into
the western U.S. Tuesday. Along with that will come drier
conditions. Minimum relative humidity values will generally range
from 10-20% for valleys. Wind gusts from around 20-30 mph with the
dry conditions will bring higher fire danger. Models are in good
agreement on isolated showers and thunderstorms for the northern
mountains as weak shortwave energy pushes through. These would be
high-based and more likely to produce gusty, erratic outflow winds
than much precipitation.

There are more differences in ensembles later into the week with
details on the trough. Most indicate it transitioning into a
closed low while remaining to the west. That would result in
continued windy conditions with isolated or scattered high-based
showers and thunderstorms. The trough would eject further east
Thursday or Friday, bringing cooler conditions and better
probabilities for measurable rainfall for southwest Wyoming and
most of Utah.

Temperatures early in the week will be around 5F warmer than
normal as the trough slides into the western U.S. As it
approaches, conditions will cool. The coolest temperatures will
likely be Thursday or Friday as the trough axis tracks into Utah.
High temperatures will be around 5-10F cooler than normal.

&&

.AVIATION...KSLC...VFR conditions with scattered to broken clouds
will prevail with isolated or scattered rain showers from roughly
16- 20Z. Light southeast winds will last into the afternoon, with
a transition to light northwest winds around 20Z. Rain showers
will be capable of altering wind directions. Light northwest winds
will transition to light southeast winds around 03Z with clouds
decreasing.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions with scattered
to broken clouds will prevail for southwest Wyoming and most of
Utah. Isolated or scattered rain showers will mainly impact
southwest Wyoming and northern Utah from roughly 16-00Z. Isolated
thunderstorms will be most common into the afternoon in southwest
Wyoming. Conditions will be drier for southern Utah, although
isolated thunderstorms are likely from roughly 19-00Z. Clouds will
decrease throughout after 00Z.

&&

.FIRE WEATHER...An ongoing surge of monsoonal moisture will result in
one more day of widespread shower and thunderstorm activity on
Saturday. Ongoing nocturnal showers will continue to progress
northward, with an increase in convective development expected
early to mid afternoon areawide. Given the abundance of moisture,
Saturday will see the best chances of wetting rainfall where any
storms track. With the potential for efficient rainfall production
out of storms, recent area burn scars will pose a flash flood
threat with any sufficiently strong cell tracking through.
Lightning and some modestly gusty outflow winds will also be
possible near this activity. Precipitation strength and coverage
wanes through the evening into the overnight, with only some
isolated nocturnal showers lingering.

A drying trend will begin Sunday as a broad system begins to push
into the west US coast. Still, lingering moisture will be
sufficient for daytime convective development, particularly
along/near high terrain, and especially for northern Utah. Enough
moisture is maintained to continue some isolated to scattered
precipitation chances into midweek, though wetting rain chances
will be more limited. Potentially more impactful, the eastward
progression of the aforementioned system will enhance
southwesterly flow by midweek, in turn increasing sustained wind
magnitudes and gusts.

&&

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

$$

SHORT TERM...Warthen
LONG TERM...Wilson
AVIATION...Wilson
FIRE WEATHER...Warthen

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http://weather.gov/saltlakecity