056
FXUS65 KSLC 071052
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
352 AM MST Thu Nov 7 2024

.SYNOPSIS...Quiet and cold conditions will see a gradual warming
trend moving into the weekend. Late weekend on into early next week,
an active and more unsettled pattern looks likely to return.

&&

.SHORT TERM (Through 12Z/5AM Saturday)...Early Thursday morning
analysis revealed a closed low located over east-central Arizona,
while an upstream high pressure ridge centered over the eastern
Pacific nosed eastward across the Northern Rockies. Through
Saturday morning, the pattern will evolve little, with the above-
mentioned low undergoing lee-side strengthening near the
Colorado/Kansas border while the ridge advances eastward into the
Great Basin. Given Utah and SW Wyoming`s positioning in between
these large-scale features, tranquil, albeit cool conditions will
prevail. Temperatures today will persist in the 5F to 15F below
normal range, while warming a couple of degrees on Friday.
Meanwhile, freeze headlines remain in place for Zion NP and Lower
Washington County. As of this 330 AM MST writing, all sensors
above 4,000ft elevation have recorded freezing temperatures
across Zion NP, and lower elevations of the zone have decoupled,
setting the stage for a widespread freeze here with observed
temperatures in the mid 30s. In Lower Washington County, boundary
layer decoupling has yet to a occur (a source of forecast
uncertainty here) and freezing temperatures have yet to be
observed. For this reason, a Freeze Watch will be continued for
Friday morning, when boundary layer decoupling is more likely to
occur. Slightly warming temperatures will offset the more
favorable radiating conditions, however, and the probability of a
freeze sits around an uncertain 30%. Should the widespread freeze
remain on track for Zion NP, the Freeze Watch for tonight will
not be needed.

.LONG TERM (After 12Z/5AM Saturday)...The long term period is
relatively quiet, except for a storm that will arrive on Tuesday
with primarily impacts to northern Utah. The period starts with near
normal temperatures across the area that will gradually warm a few
degrees above normal by Monday. A weak shortwave will be passing
over northern Utah on Sunday night, but little moisture will only
give way to a few high clouds.

Another storm with very similar characteristics to our past several
storms will be moving into the area on Tuesday. This trough will be
coming from the Gulf of Alaska and through the PNW before arriving
to the Great Basin some time on Tuesday. Guidance is a bit unsure of
the exact timing with some guidance bringing it in by Tuesday
morning and others by Tuesday evening. Regardless, 52% of members
bring most of the moisture to northern Utah with valley rain
potentially transitioning to snow and modest snow for the mountains.
The other 48% of members either keep the track further north (26%
chance) or delayed and to the southwest that would bring more
impacts to southern Utah (22% chance). Assuming the 52% chance
scenario plays out, expect a sharp cold front on Tuesday with snow
levels starting around 6500-7000 feet with ensemble mean H7
temperatures ~-9C ushering in behind the front that could get snow
down to valley floors, especially with heavier rates. This could
pose impacts to the morning commute on Tuesday, if this front
arrives early. The band moves through pretty quickly with post-
frontal northwest flow that could keep some orographics going in the
mountains through the day.

Ridging builds back into the region with temperatures gradually
climbing through the rest of the week. Another deep trough is
apparent in the clusters. This starts to push into the PNW by Friday
with a track that favors a more southern trajectory into the
weekend.

&&

.AVIATION...KSLC...VFR conditions will persist for the KSLC terminal
through the period. Dry conditions and clear skies will continue
with light diurnally driven winds.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will persist
for the entire airspace through the period. Dry conditions and clear
skies will continue with light diurnally driven winds.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Freeze Warning until 9 AM MST this morning for UTZ123-124.

     Freeze Watch from late tonight through Friday morning for UTZ123-
     124.

WY...None.
&&

$$

ADeSmet/Mahan

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