Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 251010
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
410 AM MDT Mon Mar 25 2024

.SYNOPSIS...A broad trough will bring cool and unsettled
conditions to the area through Tuesday. High pressure will briefly
return Wednesday into early Thursday before a more unsettled
pattern returns thereafter.

&&

.SHORT TERM (Through 12Z Wednesday)...A broad trough remains over
the region this morning, currently centered just east of Utah.
Early shower activity has diminished considerably, though a lake
band has developed just south of the lake near the Salt
Lake/Tooele county line. Per webcams, this precipitation appears
to be primarily falling as rain, but something to monitor going
forward.

Overall, conditions will stay relatively cool and unsettled both
today and tomorrow with maxes running about 10F below seasonal
normals each day. Showers will increase in coverage again this
afternoon due a combination of daytime heating and shortwave
energy from the main trough ejecting across the state, primarily
over northern Utah. Thus, will see showers become fairly
widespread again over the higher terrain of northern Utah this
afternoon, with scattered showers over adjacent valley locations.

Anticipating another lull this evening and overnight with the loss
of daytime heating, with things picking back up again tomorrow
afternoon as the back edge of the main trough crosses the area.
Though northern mountain accumulations will be decent today and
tomorrow, the off and on nature of the showers is expected to keep
accumulations below advisory criteria, so have not added any new
headlines at this time. With the back edge of the trough moving
out of the area Tuesday night, will see the return of high
pressure by Wednesday morning.

.LONG TERM (After 12Z Wednesday)...By Wednesday morning,
ensemble guidance remains in solid agreement on a ridge translating
through the region which will help to bring stabilizing conditions
and warmer temperatures area-wide. Though transient high pressure
will progress through the region, still expecting afternoon buildups
of clouds, with a low chance (10-15%) of a few developing into a
shower given the amount of lower level moisture in place. Overhead
temperatures are anticipated to warm slowly through the day,
allowing temperatures to rise by about 5 degrees across the forecast
area, bringing most areas to around 3-5 degrees below average.

This ridge axis is anticipated to shift downstream of the area late
Wednesday into Thursday, which will then bring focus to an upstream
trough over the northeast Pacific that is progged to progress inland
at some point late in the weekend/ early next week. There is still a
fair amount of uncertainty revolving around the progression of this
trough at this time, however, ensemble means depict this trough
sliding southward offshore of California through the weekend, then
inland early next week. Further advection of warmer air over the
forecast area is expected as the cold core associated with the low
remains offshore. Temperatures will rise by another ~3-5 degrees
across the forecast area by Thursday, allowing high temperatures to
be right around climatological normals, if not a touch above. As
this trough begins its dive offshore of the West Coast, ejecting
shortwave energy will track across the Great Basin region and will
provide fair synoptic support for precipitation over portions of the
forecast area both Thursday and Friday.

Models are still seeming to struggle with how this wave will track
across the West, mainly in reference to how far north or south it
will track, which will have an influence on the precipitation
forecast late in the week. With moisture already in place in the
lower levels, a shortwave tracking over the area will be able to
help produce lift and a resulting round of precipitation. While
ensembles continue to marginally favor the northern third of Utah
and southwest Wyoming for the most likely place to receive any sort
of precipitation, there are still nearly 45% of ensemble members
that keep a largely dry forecast across Utah and southwest Wyoming
through Thursday evening. Additionally, there is quite the spread
amongst ensemble guidance on how heavy precipitation will be with,
for example, the EPS ranging from 0 inches to over 1 inch of rain in
Salt Lake City over a 24-hour period... the top end of the GEFS
suite is nearly half of the EPS (0.5 inches). Similar uncertainties
exist heading through Friday. As far as p-type forecasts go,
expecting valley rain and mountain snow across much of Utah and
southwest Wyoming... thinking that the most uncertainty in
precipitation type lies across far northern and western Utah as these
locations will be in closer proximity (relatively) to the cold core
low.

As mentioned previously, the offshore trough is expected to push
inland late in the weekend/ early next week which will likely kick
off the next round of potentially more significant precipitation. A
vast majority of models progress the center of the trough to the
south of the UT/AZ border, which will likely influence higher
potential for precipitation in southern Utah. That said, northern
Utah and southwest Wyoming will likely stay in the mix for
precipitation potential given general instability and broad synoptic
forcing. Details become very murky with these offshore cutoff low
systems with long lead time and could even anticipate potential for
this system to linger offshore longer than expected, which would
delay everything already forecast... so continue to monitor
forecasts through the week.

&&

.AVIATION...KSLC...VFR conditions are expected through the morning
hours with shower activity anticipated to increase during the early
afternoon. Vicinity showers will be the challenge of the day,
persisting through sun down with little skill in pinning down
specific timing of showers impacting the airfield. These hit and
miss showers will have potential to drive CIGs down to around 1,500
to 2,000ft AGL during the afternoon hours. Aside from showers,
northerly winds will prevail through the day, with periods of
erratic flow possible near showers.

.REST OF UTAH AND SOUTHWEST WYOMING...Another day of
generally widespread afternoon showers and isolated thunderstorms is
expected across Utah and southwest Wyoming. Mainly VFR conditions
are expected across the area, however, individual showers could
drive CIGs down to the 1,500-2,000ft AGL mark. Snowfall, and the
resulting lower VIS, is generally expected to be limited to
terminals above 5,000-5,500ft MSL. Shower activity will make a
notable uptick after about 18-19Z, remaining active through 02-04Z.
Otherwise, winds will be generally out of a north to northwesterly
direction through the day across much of the area.

&&

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

$$

SHORT TERM...Traphagan
LONG TERM/AVIATION...Webber

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


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