Snowbird, Utah Weather Forecast Discussion

696
FXUS65 KSLC 232127
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
327 PM MDT Tue Sep 23 2025
.SYNOPSIS...High pressure builds into the area resulting in dry
conditions and warming temperatures through Wednesday along with
some easterly canyon winds. Moisture increases across the south
on Thursday that will gradually spread further north into the
weekend.
&&
.SHORT TERM (Through 12Z/6AM Thursday)...Another chilly night
tonight as clear skies, light winds, and low dew points will allow
for efficient cooling. Isolated areas across the higher terrain
such as low lying areas of the Wasatch back will see temperatures
approach freezing with most locations likely staying above
freezing. With ridging in place, high temperatures will start
rising. Temperatures on Wednesday will be near normal for most
locations.
Additionally, light easterly winds aloft will aid in more easterly
canyon winds this evening into Wednesday morning. Winds this
morning were primarily in the 30s (mph) with a couple of spots
gusting into the low 40s. Expect similar conditions tonight with
these winds confined to the mouths of canyons across northern Utah
and lower Washington county.
.LONG TERM (After 12Z/6AM Thursday)...By Thursday morning at the
start of the long-term period, we will be transitioning into more of
an active pattern as the short-lived omega block breaks down. As a
trough grazes along the US-Canada border well to our north, this
will nudge a cutoff low slightly southeastward from the Bay Area
down into SoCal, resulting in an increase in moisture across
southern Utah along southwest flow. While moisture values will be
nearing 200% of normal by Thursday evening across southwestern Utah,
instability appears to be fairly limited, thus limiting the flash
flood threat on Thursday afternoon. Still, with slow storm motions,
the wrong storm in the wrong place could produce flash flooding.
Showers and thunderstorms overnight across the south might further
limit instability heading into Friday, too. Moisture is likely to
decrease slightly statewide as the aforementioned low shifts
slightly away on Friday; this moisture availability will likely
depend on the exact movement of this low, which is proving
challenging to pin down.
By Saturday, however, this low is expected to finally start moving
northeastward, producing a secondary surge of moisture, particularly
across southern Utah. The flash flood threat thus will increase
again by Saturday afternoon. As this low continues to eject
northeastward on Sunday, it will likely move across N-AZ/S-UT as an
open wave ahead of a strong trough centered over the Gulf of Alaska.
Showers and thunderstorms will likely be higher in coverage across
much of Utah and southwest Wyoming given widespread moisture and
cooler air overhead steepening lapse rates.
Uncertainty in the longwave pattern increases greatly after Sunday,
with the aforementioned Gulf of Alaska trough likely to swing down
across some portion of the western US by early to mid week. Model
guidance appears to be pretty evenly split between different
scenarios, with low confidence in the timing and amplitude of this
trough. About a third of ensemble members suggest a stronger, faster
trough moving overhead by Tuesday, which would produce cooler,
wetter weather at the surface. Another third favor a much weaker
trough that quickly transitions back into high pressure, while the
remaining third is in between those two scenarios.
&&
.AVIATION...KSLC...VFR conditions will exist at the terminal
throughout the duration of the TAF period. West-northwest winds will
persist through around 04z before becoming east-southeast.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will exist
across all terminals through the TAF period. Gusts across all sites
will generally subside around 02-04z, though there is a slim chance
(~30%) that easterly canyon wind gusts to around 20kts could make it
to the terminals of KLGU and KOGD just before midnight, lasting into
the morning hours. As such, decided to not include in the TAF at
this time.
&&
.FIRE WEATHER...A dry airmass has settled into the area behind
yesterday`s cold front as high pressure builds. This is resulting
in clear skies and relatively light winds. Light easterly winds
aloft will enhance winds near east-west oriented canyons,
particularly across northern Utah and lower Washington county.
These winds will likely remain below advisory levels. Temperatures
will rise quickly to a few degrees above normal by the middle and
end of the week.
A cutoff low will gradually move onshore by Thursday which will
increase precipitation chances across southwestern Utah. This
moisture will gradually spread further north by the weekend. These
storms will be capable of producing heavy rainfall in addition to
gusty outflow winds.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
SHORT TERM...Mahan
LONG TERM...Cunningham
AVIATION...Worster
FIRE WEATHER...Mahan
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

NWS SLC Office Area Forecast Discussion