Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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655
FXUS65 KSLC 022300
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
400 PM MST Thu Jan 2 2025

.SYNOPSIS...High pressure will briefly move in late Thursday into
Friday before a fast moving storm system makes its way through
the area Saturday into early Sunday, with another round of snow
particularly for Utah`s northern mountains. The active pattern
then continues into the early part of the upcoming week.


&&

.SHORT TERM (Through 12Z/5AM Saturday)...Model consensus is in
excellent agreement through the short term portion of the
forecast in their relative depictions of building a midlevel
shortwave ridge axis across Utah and SW Wyoming tonight. This will
deliver a brief period of tranquil conditions to the area. As the
ridge moves off to the east on Friday, this will open the door to
increasing southwest flow as well as modest low to mid level warm
advection through the day. Temperatures will be spring-like, with
highs in the 50s for the Wasatch Front, mid to upper 50s for the
central valleys and low 60s across Lower Washington County. These
temperatures are generally 10F to 20F above normal for early
January. By Friday afternoon, 700mb winds will increase into the
40-50kt range across the western half of Utah. This will lead to
pockets of enhanced winds, especially for exposed terrain,
valleys of southwest Utah and wind-prone areas of the Tooele and
Salt Lake Valleys. Most likely surface gusts in the most wind
prone locations are generally in the 30-40 mph range, except of
course higher gusts on exposed ridgelines. Otherwise,
precipitation will blossom across northern Utah in the pre-dawn
hours Saturday, along and ahead of a cold front and associated
mid-level trough.

.LONG TERM (After 12Z/5AM Saturday)...Active weather continues at
the beginning of the upcoming weekend as a cold Pacific storm system
pushes into Utah and southwest Wyoming. Models have seemingly
trended upwards this afternoon with regards to QPF and snowfall in
the mountains of northern Utah, likely worthy of headline issuance
as we head into Friday. Central and southern Utah will still see a
fair hit of snowfall (1-6" for the NBM 25th-75th percentile),
however, the greater impacts will be confined to the northern Utah
mountains where the most likely accumulation amounts will be 6-9
inches widespread with upwards of 15-20 inches in favored terrain
like the upper Cottonwoods and northern Bear River mountains. There
is some uncertainty on when/if precipitation will end in the
mountains before another wave moves through the region early next
week, but the start time of precipitation appears pretty locked in
to early Saturday morning. A cold front progressing through the
region will help to intensify precipitation, which may bring a
period of potentially hazardous travel conditions in the high
elevation routes of northern Utah during the mid-morning to early
afternoon on Saturday... will need to dial in these details as we
get into tomorrow, but there is generally good consistency amongst
the broad resolution models.

For the valley areas of northern Utah and southwest Wyoming, not
anticipating any impactful snow accumulations as antecedent
temperatures will be quite warm. That said, the stout cold frontal
boundary will introduce an environment cold enough for snow shortly
after the period of greatest precipitation intensity, if not just on
the tail end of it, which may allow for some quick snow
accumulations in places like the Cache Valley, Wasatch Back, and
northern Wasatch Front. Valley areas most likely to see appreciable
snowfall will be in the Park City area where current 25th-75th
percentile accumulations range from 4-8 inches... will certainly
need to explore headline issuance for the Wasatch Back.

A majority of this storm is expected to be wrapped up by Sunday
morning, however, there are some models that maintain snowfall in
the terrain through Sunday afternoon/ evening. It is unlikely that
significant snow accumulations are produced during this post frontal
period, however, areas in the upper Cottonwoods could see see
another 3-6 inches of low density snow.

Another trough looks to follow quickly in the heels of this upcoming
storm on Monday morning, however, with a significant ridge building
upstream it appears a strong moisture source will be lacking. If
anything, it looks like this next storm will just be bringing a
refresh of snowfall in the mountains before we shut off the moisture
tap. At this point, not considering headlines for this early week
storm. Heading into the middle of next week, the aforementioned
significant ridge over the PacNW region will remain in place and
potentially intensify, placing downstream areas under a strong
blocking pattern. Any troughs that move through the region would be
sourced from interior Canada, meaning that chances for significant
storm systems will be quite low. Bottom line, our snowpack is going
to be struggling in the long term.

&&

.AVIATION...KSLC...Light and variable easterly winds are expected to
become typical diurnal southeasterlies around 02-03z. Any lingering
scattered cloud cover should dissipate by 00z, with a 30% chance of
remaining into the evening, above 6kft agl. VFR conditions will
persist through the TAF period before the next storm fires up early
Saturday morning.

.REST OF UTAH AND SOUTHWEST WYOMING...At the northern terminals,
SCT/BKN cigs are expected to dissipate around 00z, lingering a bit
longer at LGU. For the southern terminals, weather remains quiet
with VFR conditions and some SCT/BKN layers well above 12kft agl.


&&

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

$$

ADeSmet/Webber/Verzella

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