153
FXUS65 KSLC 231009
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
409 AM MDT Thu May 23 2024

.SYNOPSIS...Warm dry and breezy conditions will persist across
portions of southern Utah through Friday, while a cooler and more
stable air mass resides across the north. A more potent weather
system will bring widespread precipitation to much of northern and
central Utah Saturday, along with a cooling trend across the
south. Warm and drier conditions will return next week..

&&

.SHORT TERM (Through 12Z/6AM Sunday)...Early morning water vapor
imagery and objective analysis depict an upper low progressing
eastward across southern Idaho, with the associated low level
baroclinic zone stretching across southwest Wyoming and northern
Utah. The surface front extends along a line from roughly Vernal
to Milford, and as this boundary has continued to progress south
post frontal winds across northern Utah have largely abated. As
such allowed the Wind Advisory to expire at 3AM. Lift along the
aforementioned baroclinic zone is resulting in weak bands of
precipitation across northern Utah/southwest Wyoming, and these
may persist beyond sunrise mainly east of the Wasatch Crest before
ending by late morning.

The frontal boundary will be slow to push through southern Utah
today, and as a result another day of warm, dry and breezy
conditions is expected across the lower deserts from St George
east to Lake Powell, and north to Hanksville. Temperatures across
these areas will again top out in the upper 70s to mid 80s (St
George/Zion). Meanwhile, the airmass behind the passing front is
much cooler, and temperatures across northern and central Utah
will trend 10 to 15 degrees cooler today, struggling to reach the
60F mark along the Wasatch Front. A favorable pressure gradient
will result in elevated post frontal winds across the western
Uinta Basin and potentially Castle Country as well. These should
remain below advisory criteria but will need monitoring.

The shallow surface front will briefly push through southern Utah
this evening, while the trailing 700mb baroclinic zone stalls
across central Utah. This surface boundary will quickly mix
northward Friday, eventually stalling across central Utah by mid
afternoon. In the wake of this retreating boundary, warm dry and
breezy conditions will return to southern Utah Friday afternoon,
while a more stable airmass remains entrenched on the cool side of
the boundary across northern Utah. Despite this, the airmass will
modify allowing temperatures to trend 7-10F warmer Friday
afternoon. Additionally, increasing moisture and weak ascent ahead
of an approaching shortwave will bring a chance for
showers/thunderstorms along and north of the stalled boundary
Friday afternoon and evening.

The next upper low will dig along the Pacific Northwest coast
Friday, then spread inland across the northern Rockies Saturday.
Mid level frontogenesis along the stalled baroclinic zone coupled
with an influx of moisture associated with the approaching low,
and the eventual passage of a shortwave trough rotating around
the base of the upper low will work together to bring widespread
precipitation to much of northern and central Utah throughout
much of Saturday. Snow levels will remain generally above 8000
feet across northern Utah, and 9000 feet across central Utah.
Precipitation will remain more spotty across southern Utah as the
frontal boundary pushes through this area Saturday afternoon.
Precipitation will taper off late Saturday afternoon into Saturday
evening as the aforementioned shortwave moves east of the area.
The exception may be areas along the Idaho border in closer
proximity to the passing upper low Saturday night.


.LONG TERM (After 12Z/6AM Sunday)...Through Sunday, should see
precipitation tapering off as the system from the prior day(s)
departs eastward. Temperatures will warm from that of Saturday,
but afternoon highs areawide will remain below seasonal normal for
late May.

Deterministic and ensemble model guidance continues to show good
consensus in support of a building ridge from Memorial Day on into
midweek. This will yield dry conditions and a warming trend, with
afternoon highs likely near normal on Monday, increasing to above
normal moving into the middle of the week. In comparison to prior
forecasts, NBM has backed off slightly on the potential for the
first 90F or higher day Wednesday afternoon (down to 22% now at
KSLC). This appears to be due to potential for an amplifying
trough in the PacNW to flatten the ridge or shunt the ridge axis a
bit more east of the area, seemingly supported by ~50% of
ensemble members. Generally would just anticipate this to result
in slightly cooler (but still above normal) temperatures, though
something more aggressive/amplified like what the deterministic
GFS depicts would certainly be more interesting. This split in
ensemble scenarios carries on into Thursday as well, though even
then there is ~25% of ensemble membership which support a
continued strong ridge. Overall though, looks favorable for a
period of more summer-like weather with several days with highs in
the low to mid 80s across much the Wasatch Front, and mid to
upper 90s in Lower Washington County. While beyond the forecast
period, CPC 8 to 14 day also leans in favor of warmer/drier
conditions in comparison to normal, so some sort of ridge
dominated pattern seems favored to largely persist.

&&

.AVIATION...KSLC...In the wake of departing system, terminal will
see continued NW winds through the day Thursday, with some gusts
up to 25 kts or so possible during the afternoon. Expect winds to
gradually relax approaching sunset, with a switch back to lighter
SE winds between ~03-05Z early Friday. Otherwise, expect coverage
of VFR cloud cover to generally decrease through the day.

.REST OF UTAH AND SOUTHWEST WYOMING...Most active portion of
system will continue to depart the region. Behind the front, a
continued north to northwest wind direction will generally be
favored at most terminals. Many terminals will also see some
modest gusts, generally in the 20-30 kt range during the day
Thursday. Otherwise, expect generally lessening cloud cover at
northern terminals, with clear to mostly clear skies persisting at
southern terminals.

&&

.FIRE WEATHER...A cold front across central Utah early this
morning will slowly push south through the day today. Ahead of
this front, warm dry and breezy conditions will persist across
south central, southeast and east central Utah, where afternoon RH
will fall below 15% and winds will gust into the 25-35 mph range.
Further north, a much cooler air mass behind this front will
result in temperatures trending 10 to 15 degrees cooler across
northern and central Utah. This front will briefly push through
southern Utah this evening turning winds northwesterly, before
retreating north early Friday, and stalling across central Utah
Friday afternoon. Warm, dry and breezy conditions will spread
across southern Utah again Friday to the south of this front,
while the airmass remains more stable but trends a few degrees
warmer across northern Utah. Just enough moisture in the vicinity
of this front will allow for a few showers and thunderstorms
Friday.

A more organized weather system will move into the region
Saturday, bringing fairly widespread precipitation to much of
northern and central Utah. This system will also push the cold
front through southern Utah resulting in a cooling trend along
with a chance of showers and thunderstorms. A warming and drying
trend will follow for the early portion of next week.

&&

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

$$

SHORT TERM...
LONG TERM...
AVIATION...
FIRE WEATHER...

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