983
FXUS65 KSLC 182158
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
358 PM MDT Wed Jun 18 2025

.SYNOPSIS...Hot, dry, and windy conditions spread across Utah and
southwest Wyoming through the next 48-72 hours, bringing increased
concerns for fire weather conditions and risk of heat related
illness. A dry cold front pushes into the region over the weekend,
bringing temperatures back to near normals levels. That said, very
dry conditions are expected to remain in place through at least
the middle of next week.


&&

.SHORT TERM (Through 12Z/6AM Friday)...A ridge of high pressure,
currently centered over the eastern Great Basin, will crest
through the remainder of the forecast area overnight, opening the
door to destabilizing conditions and significantly warming
temperatures. As this process occurs, a trough currently in the
Gulf of Alaska will dip farther south and cause wind speeds
overhead to increase in speed. With deep atmospheric mixing
in place, stronger winds are anticipated to begin materializing at
the surface. Widespread gusts in excess of 25-30 mph are expected
during the afternoon hours tomorrow which, when combined with the
very dry atmosphere, will help to generate widespread fire weather
conditions. These fire weather concerns are expected to persist
into the weekend, largely before the upcoming dry cold front
arrives in Utah/ southwest Wyoming (see the fire weather section
for more details).

In addition to the concern for fire weather conditions, a
significant rise in temperatures heading through the day tomorrow
will bring concerns for heat related weather hazards. Numerical
weather prediction model output shows widespread areas of greater
than an 85 percent chance of high temperatures exceeding 100
degrees in northern Utah, particularly along the Wasatch Front,
West Desert, and Delta area. With urbanized areas expected to see
minimal relief from the heat during the overnight hours, risk for heat
related illnesses will be increased. As such, the existing Heat
Advisory remains in place. For other areas, hot conditions are
still expected (e.g. St. George at 107, Green River at 105, Price
and Logan nearing 100), but overnight temperatures are expected to
fall to a level which will provide relief from the heat.

.LONG TERM (After 12Z/6AM Friday), Issued 428 AM MDT...

Temperatures will not be in record territory Friday, as a
longwave trough approaches the PacNW and high pressure to the
southeast slides east. Temperatures will continue to be warmer
than normal, with valleys generally in the mid or upper 90s.
Slightly cooler conditions will be the main change from Thursday,
as southwest winds will remain enhanced. Sustained wind speeds
much of the afternoon will range from 15-25 mph with gusts of
35-40 mph. Minimum relative humidity values will be in the single
digits to teens with minimal increases at night.

The longwave trough will track into the western U.S. Saturday.
Ensembles are in good agreement on its track, with the main
uncertainty on how fast a baroclinic zone tracks into Utah. That
boundary will be the line where Red Flag conditions continue to the
south. Sustained winds for locations south of the front Saturday
will range from 20-30 mph with gusts of 40-50 mph. Gusts will peak
in excess of 50 mph. Red Flag Warnings, which start Thursday,
continue through Saturday for much of Utah.

The trough and front will not bring precipitation, but they will
bring strong cold air advection. By Saturday night, the front will
likely track into southern Utah. Valleys north of that will cool
into the 40s to around 50F. Higher elevation valleys like the Bear
River Valley, Ogden Valley, and Uinta County, Wyoming will lower
into the low 30s. Valley highs Sunday will mainly be in the 70s,
while southeast Utah and lower Washington County reach the 90s.

The longwave trough will lift north Monday, but shortwave energy
will break off that trough to keep a trough in place for the western
U.S. The trough axis will be to the west, which will allow for more
enhanced southwest flow. Temperatures will warm to near normal
Monday and to warmer than normal Tuesday. Although southwest flow
will be enhanced, winds will be lighter than the conditions which
prompted the Red Flag Warning. Relative humidity will continue to be
very low, with minimums in the single digits to teens.

&&

.AVIATION...KSLC... Winds are expected to become predominately
southeasterly around 04z this evening and become southwesterly
around 12-15z. Beginning as early as 16z, gusts nearing 20kts will
begin to develop near the terminal. From around 20-06z, gusts up to
30kts out of the south are possible at the terminal. They are
expected to taper off somewhat throughout the evening, though gusts
greater than 20kts will likely hold on through Friday morning.

.AVIATION...REST OF UTAH AND SOUTHWEST WYOMING... Winds will remain
tame across all sites before clocking to southwesterly and seeing an
increase in winds around 12-15z tomorrow. All sites will see gusts
ranging from 20-30kts develop from around 18-00z as well with the
highest confidence for 30kts or greater at KEVW, KCDC, and KBCE
during the aforementioned timeframe. Regarding KBCE, another night
of MVFR vsbys appears possible as winds lighten up overnight with
smoke settling over the terminal from the France Canyon Fire. There
remains uncertainty with this, but MVFR vsbys appear most likely
from 08-14z tomorrow.

&&

.FIRE WEATHER...The axis of a ridge of high pressure crests the region this afternoon, opening
the door to deeper instability across Utah as well as some of the
hottest temperatures we`ll see over the next 7 days. Concurrent
with the center of the ridge departing to the east, a trough in
the Gulf of Alaska will dip farther south, eventually pivoting
into Utah over the weekend. Ahead of this trough, an increase in
southwesterly winds is expected across Utah from Thursday through
Saturday. Each day during this period, winds will increase
progressively from day to day, peaking in speed on Saturday
afternoon just ahead of an approaching cold front. Strong, dry
southwesterly flow will combine with very low afternoon humidity
in the 5-10 percent range, leading to widespread areas of critical
fire weather conditions. As such, Red Flag Warnings remain in
place for all areas in Utah which have been deemed to contain
"critical" or "approaching critical" fuel status.

As the aforementioned cold front creeps closer to Utah on Friday,
winds across the northern area will drop below RFW criteria while
areas in central and southern Utah continue to increase. By Friday
and Saturday winds are anticipated to gust upwards of 35-45 mph
across much of Utah from the Cedar City area northeastward
through the Uinta Basin. For Saturday, just before the front pushes
through, there is anywhere from a 10-50% chance that winds gust in
excess of 50 mph throughout the southern half and eastern half
of Utah with the highest likelihood area being Castle Country. By
Sunday, much cooler temperatures spread across the region in the
wake of the cold front, however, afternoon humidity will remain
critically dry through at least the middle of next week.


&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Red Flag Warning from noon Thursday to 10 PM MDT Friday for
     UTZ478.

     Heat Advisory from noon to 11 PM MDT Thursday for UTZ101>106.

     Red Flag Warning from noon Thursday to 10 PM MDT Saturday for
     UTZ482>484-489-492>498.

WY...None.
&&

$$

SHORT TERM...Webber
LONG TERM...Wilson
AVIATION...Worster
FIRE WEATHER...Webber

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