363
FXUS65 KSLC 210436
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1036 PM MDT Sun Sep 20 2026

.KEY MESSAGES...

- High pressure will keep conditions dry and stable across Utah
  and southwest Wyoming through Monday afternoon with temperatures
  near seasonal normals.

- A Pacific trough will bring showers and thunderstorms to
  southwest Utah beginning Monday night, with the potential for
  convection spreading across the remainder of the forecast area
  during the day Tuesday. Any storms that develop could produce
  gusty winds, lightning, hail, and heavy rain that could lead to
  isolated flash flooding.

- Dry conditions are expected to return to the majority of the
  area for the latter part of the week with a slow warming trend
  in temperatures. Deeper moisture will linger over far
  southeastern Utah, keeping the potential of at least isolated
  showers and thunderstorms for that area.

&&

.DISCUSSION...Weak ridging is in place over Utah and southwest
Wyoming this evening bringing dry conditions and relatively light
flow aloft. A broad upper low is approaching the California coast,
and a few high clouds are streaming into the area out ahead of it.
Temperatures today were in the vicinity of 5-7F below seasonal
normals for northern Utah and southwest Wyoming, with highs near
normal over southern Utah.

With the California low expected to open up and move into the
Great Basin by late Monday, southerly flow will increase over the
area by Monday evening. This will allow moisture to advect
northward, albeit not as much as we saw last week. The combination
of that and the position of the low will allow for showers and
thunderstorms to develop over southwestern portions of the area
overnight Monday into Tuesday morning. The trough is expected to
continue eastward across the area during the day Tuesday as it
weakens significantly. Scattered to numerous showers and
thunderstorms are anticipated by Tuesday afternoon, with the best
coverage over the higher terrain of central and northern Utah. Any
storms that develop will be capable of producing gusty winds,
lightning, and small hail as well as heavy rain that could lead to
isolated flash flooding, particularly for prone areas like slot
canyons, burn scars, and normally dry washes.

By Wednesday, most of what`s left of the trough will have moved
east of the area, though most guidance indicates a small piece of
the trough lingering off the coast of northern Mexico on Wednesday
as ridging moves over the top of it, creating a weak Rex Block
pattern. Most guidance then indicates a relatively light or a
zonal flow over the area for the latter part of the week, keeping
most of the area dry with a slow warming trend. It does look like
the monsoon hose stays over far southeastern Utah, however,
keeping at least some potential of showers and thunderstorms in
place. There is some noticeable spread in the guidance, however,
on how far west this hose stays, with some guidance keeping most
of the moisture over Colorado and far eastern Utah.


&&

.AVIATION...

KSLC...VFR conditions will persist at KSLC through the TAF period.
Expect clear skies overnight with increasing mid-to-high level
clouds throughout Monday. Winds remain generally light with typical
diurnal shifts, with the next wind shift to northwesterly around 18z.

REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected to
persist across all terminals through the TAF period with diurnal
wind shifts. Mid-to-high level clouds stream in from the southwest
overnight into Monday. Isolated rain showers are possible after
22z for southwest Utah terminals, but impacts will be limited.

&&

.FIRE WEATHER...High pressure will keep conditions over the area
dry into Monday with generally light and terrain driven winds and
temperatures near seasonal normals. Southerly winds are expected
to increase Monday evening ahead of an approaching trough, and
this will draw deeper moisture back northward and bringing the
return of showers and thunderstorms. Monday night`s storms will be
focused over southwest Utah, with convection spreading into the
remainder of Utah during the day Tuesday as the main trough moves
through (as it weakens). Any storms that develop will be capable
of bringing gusty and erratic winds, frequent lightning, and an
increase probability of wetting rainfall. Drier conditions will
develop for the latter part of the week for much of the state with
a slow warming trend in temperatures. However, deeper moisture is
expected to remain over far southeastern Utah, keeping the
potential for showers and thunderstorms going there through the
work week.

&&

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

$$

PUBLIC...Traphagan
AVIATION...Whitlam
FIRE WEATHER...Traphagan

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