St. George, Utah 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

605
FXUS65 KSLC 211014
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
308 AM MST Thu Nov 21 2024

.SYNOPSIS...Dry and mild southwesterly flow will prevail across
the region through the remainder of the work week. A series of
Pacific storm systems will impact the region beginning this
weekend, and continuing through the middle of next week.

&&

.SHORT TERM (Through 12Z/5AM Friday)...Mild southwesterly flow
will persist across the forecast area through the short term
period allowing for a continued warming trend. Max temperatures
will trend another 4-6 degrees warmer this afternoon, reaching the
mid/upper 50s along the Wasatch Front, and low/mid 60s across
lower Washington County. Max temperatures will then trend another
2-4 degrees warmer Friday afternoon. Any threat of precipitation
through the short term will remain confined to the Raft River
range and vicinity across far northwest Utah today and again late
Friday night.

.LONG TERM (After 12Z/5AM Friday)...Ensemble members continue to
trend towards less QPF for the weekend storm, but a slight uptick in
QPF has been the trend for the storm midweek next week. There is
still a lot of uncertainty amongst the guidance regarding the
upcoming pattern change.

Warm southerly flow aloft will be in place on Friday as high
pressure will be shifting to our east and an impressive low will be
rotating off the PNW coast. Temperatures Friday will be running 5-10
degrees above normal.

A PNW atmospheric river is currently ongoing across the PNW from
northern California up through British Columbia thanks to an
impressive cyclone off the PNW coast. This cyclonic circulation will
stay mostly stationary off the coast of southern British Columbia
through the weekend and into early next week. This cyclone will
eject a shortwave to the east this weekend with flow aloft
transitioning to westerly allowing moisture to advect into the
region. A stout 130+ knot jet will accompany the wave and provide
modest synoptic scale accent within the left exit region of the jet
to generate widespread precipitation. The question is where this
exit region sets up. ~42% of ensemble members orients the jet in
such a way that would favor more widespread precipitation across
Utah (with a focus across northern Utah) and SW Wyoming. The
remaining membership depicts a drier scenario with the bulk of the
forcing going by to our north where most of the precipitation will
be located. This difference is evident in the wide range in QPF
totals in the 25th-75th percentiles. 75th percentile precipitation
is ~0.5-0.6" across most valleys of central and southern Utah, with
lesser amounts further south, and ~1"+ for mountain areas. These
totals are cut in half, or more, for the 25th percentile.

H7 temperature ensemble means bottom out ~-8C behind a surface cold
front across northern Utah/SW Wyoming on Sunday morning suggesting
snow levels likely remain above valleys floors. A band of
precipitation will likely accompany this baroclinic zone. Behind the
front, winds aloft will switch to a west/northwest orientation as
cold air advection ushers in a drier airmass. This frontal boundary
will likely stall across Utah, currently projected to stall across
central Utah. This could keep a longer duration band of
precipitation ongoing wherever this front stalls.

Most of the guidance is in favor of a return to southerly flow and
shortwave ridging on Monday that would bring a brief lull in
activity. There is a 60% chance of the aforementioned cyclone moving
onshore and through the region by late Tuesday into Wednesday with
the other 40% keeping it offshore with continued ridging. The more
likely scenario would favor colder conditions that could bring
accumulating snow to valley locations.

&&

.AVIATION...KSLC...VFR conditions will persist for the KSLC terminal
through the remainder of the period. Scattered to broken mid level
clouds will continue through the day with southerly winds
transitioning later in the afternoon ~22Z to a brief and
light northerly lake breeze.

Rest of Utah and Southwest Wyoming...VFR conditions will persist
across the entire airspace. High pressure will keep conditions dry
with some scattered midlevel clouds to the northwest. Winds will be
light and diurnally driven.

&&

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

$$

Seaman/Mahan

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