Anchorage, Utah Weather Forecast Discussion

411
FXUS65 KSLC 082158
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
358 PM MDT Mon Sep 8 2025
.SYNOPSIS...Southwest flow will build into the region through at
least Thursday ahead of an upper level disturbance. Chances of
accumulating precipitation increase Friday across northern and
central Utah, with temperatures falling around 5 to 10 degrees
below normal. Drier conditions will build into the area for next
weekend.
&&
.SHORT TERM (Through 12Z/6AM Wednesday)...Afternoon satellite
analysis shows a more interesting upper-level pattern than we`ve
experienced lately. A low pressure system is currently churning
just off the coast of CA/OR, with a ridge continuing to shift to
our east. Overhead, westerly flow is gradually becoming more
southwesterly through the column, with a broad area of upper-level
diffluence over the region. Showers and thunderstorms have
remained isolated at best so far this afternoon given modest
moisture despite some synoptic lift ahead of the aforementioned
low.
This evening, RAP analysis suggests a relatively small area of
enhanced PW moving from southwest to northeast, crossing the
Wasatch Front around or just after midnight. An area of showers
and gusty outflow winds may develop along this feature, though
high-res models are struggling with the exact placement; some CAMs
favor a placement through the Salt Lake Valley, others favor a
track further north near the UT-ID border, while others favor a
weak feature overall.
Tuesday appears to be a similar day to today, with isolated
convection developing during the afternoon, mainly across northern
Utah/southwest Wyoming. The main difference will be increasing
southwesterly winds during the afternoon, with surface wind gusts
approaching 30-35 mph across portions of western Utah, namely
western Millard and Iron counties...with gusts to 20-30 mph
elsewhere.
.LONG TERM (After 12Z/6AM Wednesday), Issued 314 AM MDT...With
the upper level trough now approaching the Reno area Wednesday,
drier air will work into the state, with 700mb winds increasing to
35kts or so. Humidities will once again fall to near 15% or below
across western Utah. This will bring another period of locally
critical fire weather conditions.
By Friday, ensemble systems represent a range of solutions that
largely support an upper level low shifting into the Great Basin
by Friday afternoon. One of the bigger questions is how quickly
dry air will work into Utah. Around 20% of the members are much
quicker to bring this dry air into Utah, thus reducing the threat
of widespread precipitation across northern and central Utah. The
remaining 80% of members suggest this drier air will hold off
sufficiently to allow for more widespread precipitation across
northern and central Utah as the upper level low ejects across the
region.
Given unstable conditions in the colder airmass behind this upper
level system, additional convection will be possible Saturday
afternoon, particularly across northern Utah. Temperatures will
average around 5-10 degrees below normal by Friday, closer to
around 5 degrees or so below normal over the weekend.
While a shortwave ridge will build into Utah once again next
weekend, the next upper level trough will already be approaching
the Pacific Coast.
&&
.AVIATION...KSLC...Northerly winds just now in place are expected to
hold into this evening prior to increased wind variability, this due
to an increasing trend of shower and/or thunderstorm potential
(namely after 02z). A 30% chance continues to exist for showers and
variable winds within the 02-07z timeframe, but now also seeing a
20% of a more developed thunderstorm between 02-05z. Post,
southeasterly winds will prevail later tonight through Tuesday with
speeds likely exceeding 26kts by Tuesday afternoon.
.REST OF UTAH AND SOUTHWEST WYOMING...In large VFR conditions will
dominate the airspace this valid TAF period, with southwest winds
trending to increase on Tuesday (western valleys >30kts pm hours.
Said, isolated showers and thunderstorms are expected in northern
Utah and southwest Wyoming during the first half of tonight, with
redevelopment over and downstream of mountain areas east of I-15
Tuesday. The primary impacts from any of these isolated storms will
primarily be from brief gusty/erratic winds and potential reductions
to MVFR as storms pass.
&&
.FIRE WEATHER...As a low pressure system slowly approaches and high
pressure shifts to our east, expect a subtle drying trend and increasing
southwesterly flow through Wednesday. With minimum RH in the mid-
teens and wind gusts of 30-35 mph on Tuesday afternoon and 30-40
mph on Wednesday afternoon across western valleys, pockets of
critical fire weather conditions are possible in areas with
sufficiently dry fuels. Overnight RH recoveries will be poor in
these areas, but marginal to good elsewhere. Although the air mass
is relatively dry, isolated to scattered showers will still be
possible across higher terrain each afternoon, particularly over
northern Utah.
As the low pressure system moves closer later in the week, winds
will weaken, chances for wetting rain will increase, and
temperatures will gradually fall. Precipitation chances are
expected to be highest on Friday, but there is some uncertainty
with how quickly drier air moves in and if there is locally
enhanced precipitation along a weak cold front.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
Cunningham/Kruse/Merrill
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NWS SLC Office Area Forecast Discussion