950
FXUS65 KSLC 141000
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
400 AM MDT Sat Sep 14 2024

.SYNOPSIS...Southwesterly flow will spread across the region today
bringing dry conditions and near to slightly above normal
temperatures. This flow will strengthen Sunday into Monday ahead
of an approaching storm system, as well as allow for an increase
in moisture. A cold front will move through the area Monday night
into Tuesday, with cooler and unsettled conditions through the
remainder of the week.

&&

.SHORT TERM (Through 12Z/6AM Monday)...Zonal flow temporarily in
place across the Intermountain West early this morning will back
through the day today, as the next upper trough begins to dig
along the Pacific Northwest coast. This backing flow will allow
for a warming trend across the forecast area today. This trend
will be most notable across northern Utah, where a lingering cool
and stable airmass will erode, allowing for a 10 degree warming
trend from Friday to Saturday. Across southern Utah, where a more
mild and seasonal airmass is already in place, temperatures will
trend 2-3 degrees warmer today.

The upstream trough will continue to dig along the Pacific Coast
tonight into early Sunday, before beginning to pivot inland
across the southern Cascades/northern Sierra Sunday night. As this
happens, the flow aloft will continue to strengthen and result in
breezy to locally windy conditions across western Utah Sunday
afternoon. Temperatures will continue to run nearly 5 degrees
above climo across the north, and near climo across the south.

Broad synoptic forcing ahead of the approaching trough will allow
for a chance of showers and thunderstorms during the day Sunday.
Later Sunday into Sunday night, the northern periphery of remnant
moisture from Tropical Storm Ileana may begin to spread into
southern Utah, although the bulk of this moisture will remain
displaced south and east of the area. Nonetheless, will need to
monitor for enhanced rainfall with any showers/thunderstorms
which develop in this area late in the short term period.

.LONG TERM (After 12Z/6AM Monday)...Ensemble members are in
excellent agreement early in the long term forecast period with a
trough over the West Coast states, anchored over central
California. This pattern will place the forecast area in enhanced
deep southwesterly flow on Monday. Though cloud cover will limit
mixing somewhat, with 700 MB winds of 40 to 50 knots, expect
surface wind gusts to be solidly into Wind Advisory criteria over
much of western Utah, with area well-depicted by ECMWF Extreme
Forecast Index. Of note, NBM 24 hr Max Wind Gust probabilities
indicate a 30 to 50 percent chance of winds reaching High Wind
Warning criteria Monday afternoon. With synoptic support
increasing as the trough approaches, will continue to see
precipitation chances remain elevated (roughly 70 percent northern
half of Utah and 30-50 percent southern half) areawide. Will also
need to monitor for deep residual moisture from Tropical Storm
Ileana, currently progged to be over southeast Utah on Monday,
though shifting eastward.

Ensemble consensus is that a northward and eastward progression
of the trough will occur on Tuesday, though with some differences
in the amplitude of the trough and movement. Precipitation chances
will remain elevated (40-70 percent over northern utah). Drier
air advecting into southern Utah will limit any precipitation
potential. With much cooler air moving into the Great Basin, high
temperatures on Tuesday will be 10 to 15 degrees below normal.
Despite the cooler air aloft, snow levels will remain elevated,
generally at or above 10,000 feet, with minimal, if any, snow
accumulation.

Much uncertainty is noted for the pattern evolution from
Wednesday through Friday, with significant timing differences in
the evolution and movement of a second trough of low pressure
digging into the Great Basin. In general though, an unsettled and
cool pattern is expected to continue through the remainder of the
workweek.

&&

.AVIATION...KSLC...VFR conditions will persist through the valid
TAF period. Winds are expected to stay light (generally less than
10 knots) and follow the diurnally typical direction pattern, with
southeast winds shifting to the northwest around 18Z, and then
back to the southeast around 03Z.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail
through the TAF period, with generally light winds following
typical diurnal direction patterns.

&&

.FIRE WEATHER...Southwesterly flow will begin to spread across
the region today allowing for a warming trend. This trend will be
most pronounced across northern Utah where high temperatures will
trend nearly 10 degrees warmer than Friday, while across southern
Utah temperatures will trend 2-3 degrees warmer today. With this
warming, afternoon RH will trend much lower across the north, with
little change across the south.

The next storm system will approach the region Sunday into
Monday. Southerly flow will strengthen ahead of this system,
resulting in breezy south winds Sunday, followed by stronger south
winds Monday. However, RH will also be increasing ahead of this
system, remaining above 15% across all elevations both Sunday and
Monday, and as such critical fire weather conditions are not
expected despite the increase in south winds. This increase in
moisture will bring a chance for showers and isolated
thunderstorms Sunday across all areas, with a better chance for
precipitation becoming concentrated across northern Utah late
Sunday through Tuesday as the approaching storm system passes
through the region. A cool and unsettled pattern will persist
through much of next week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...Red Flag Warning from noon today to 7 PM MDT this evening for
     WYZ277.

&&

$$

Seaman/Barjenbruch

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