Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 261003
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
403 AM MDT Tue Mar 26 2024

.SYNOPSIS...Cool and unsettled conditions will continue today with
the passage of a trough. High pressure will bring dry conditions
and a warming trend for the midweek period. A more active pattern
will return for late in the week and into the weekend.

&&

.SHORT TERM (Through 12Z/6AM Thursday)...The first piece of the
broad trough that has been impacting the region has ejected into
the central United States this morning. Moisture and instability
remain over Utah and southwest Wyoming, however, as the back side
of the trough remains over the Great Basin. Have seen a relative
lull in precipitation overnight, though lake effect showers
continue. As the flow aloft is now roughly a west to WNW
direction, the focus of the showers is for areas east of the lake
in Davis and Weber counties as well as points directly east. A
look at webcams indicates that most of the showers are relatively
light, producing some wet roads in valley locations. However,
would not be surprised to see a bit of slush this morning for
impacted higher elevation roadways.

The back edge of the trough will make its way east during the day
today, crossing Utah and southwest Wyoming through early
Wednesday. This back edge has some jet support with it, so
anticipating convective showers to become fairly widespread over
the northern two-thirds of the area, particularly over the higher
terrain. Overall accumulations will be generally on the light side
for the higher terrain and limited at best below, but there will
be some pockets of thundersnow and graupel that would result in
some temporary travel difficulties. Temperatures across the area
will remain on the cool side, with maxes averaging 10F below
seasonal normals.

As the back edge of the trough finally exits, high pressure will
move in for Wednesday. This will bring dry conditions with a
noticeable warming trend. Highs should approach normal for this
time of year over southern Utah, but will stay up to 5F below
climo over northern Utah.

.LONG TERM (After 12Z/6AM Thursday)...After a brief break from the
wet weather, Thursday forward will feature a return to an active
pattern with multiple rounds of precipitation in store for both the
northern and southern half of the forecast area. The broad pattern
will be characterized by a ridge departing to the east and a trough
deepening and diving offshore of the West Coast, eventually making
its way inland to make impacts across portions of the southwestern
U.S.

For Thursday, the axis of the ridge will be downstream of the area
with the eastern periphery of a broad trough creeping into the
eastern Great Basin region. A shortwave trough rounding the base of
this broad trough will cross the forecast area through the day,
helping to drape a weak baroclinic zone across the northern half of
the forecast area. With low- to mid-level moisture remaining in
place, the interaction between the mid-level shortwave, moisture,
and baroclinic zone will help to focus an area of precipitation along
the near surface boundary. Latest deterministic model guidance shows
this boundary draping as far south as northern Beaver County. Given
the warm antecedent conditions, nearly all valley areas below 6,500-
7,000ft will start as rain, with snow expected above this elevation
band. There is some uncertainty revolving around how quickly this
area of precipitation will begin to form, however, consensus is
pointing toward precipitation pushing into NW Utah during the early
afternoon hours on Thursday, progressing into the Wasatch Front by
the late afternoon/ early evening, then to areas southward through
the overnight hours. Precipitation is expected to linger on Friday,
with southerly return flow aiding in the northward regression of
this area of precipitation through the day on Friday. Not expecting
headline worthy snow accumulations in the mountainous terrain,
however, the northern Utah mountains could see 4 to 8 inches. Snow
levels are anticipated to rise on Friday as warm advection spreads
across the area, potentially driving rain up to to 7,000-7,500ft
elevations late Friday. Thankfully, strong forcing will not be in
place, thus the potential for heavier rain on snow is generally
low... but something to keep an eye on.

Additionally, ahead of the aforementioned boundary, lower level flow
is expected to increase through the morning and early afternoon
hours and could bring a period of gusty winds around 35-40 mph to
areas west of the I-15 corridor from Juab County to Iron County.
While no headlines for winds are being considered at this time,
travel along east-west oriented routes (e.e. US-50/6) may become
difficult for high-profile vehicles.

Going forth into the weekend, there is still a considerable amount
of uncertainty with the offshore trough, with a lot of the
uncertainty revolving around how quickly this feature moves inland.
How quickly this feature begins its track inland will ultimately
determine when we`ll begin to see precipitation spread over the
forecast area and when we`ll start to see temperatures decrease once
again. At this point in time, ensemble mean guidance begins to shift
this feature inland by Monday evening, which would bring the best
chances for precipitation from Monday morning onward. That said,
about 45% of ensemble members (majority in the GEFS suite) support
the center of the trough pushing inland by Sunday evening which
would allow precip to begin spreading across the area Sunday through
Monday. Regardless, with the base of the trough anticipated to
progress through the SoCAl/AZ/NM region, expecting the highest
potential for heavier precipitation across the southern third of
Utah. Even then, enough forcing will be in place across the eastern
Great Basin region that we should see precipitation spread across
much of the area... just with lighter accumulations across the
northern half of the area.

&&

.AVIATION...KSLC...Vicinity shower activity is expected to persist
through the morning hours, with a brief lull in activity mid-
morning, then increasing once again after 18-19Z. There is about a
50% chance that a shower impacts the airfield after 19Z. VFR
conditions will prevail while the airfield is not impacted by a
shower, with lower end MVFR conditions anticipated under showers due
to lowering of CIGs. Otherwise, south winds will prevail through the
mid-to-late morning, transitioning to NW flow around 17Z. Winds may
shift NW as early as 15Z.

.REST OF UTAH AND SOUTHWEST WYOMING...Afternoon shower and isolated
thunderstorm activity is expected once again today, with VFR
conditions prevailing outside of showers. Areas under showers will
see MVFR to IFR conditions due to lower CIGs, with the highest
chance of IFR conditions across the northern half of the area and
higher elevation terminals (e.g. KBCE and KEVW). Higher elevation
sites will also see the highest likelihood of snowfall and LIFR
conditions due to both VIS and CIGs. Showers are expected to
decrease in activity after 03Z. Otherwise, winds will remain out of
a north to northwesterly direction with gusts peaking around 15-20
kts in northern Utah/ southwest Wyoming and 20-25 kts in southern
Utah.

&&

.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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