878
FXUS65 KSLC 181028
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
428 AM MDT Wed Jun 18 2025
.SYNOPSIS...Utah and southwest Wyoming will see continued dry
conditions over the next several days, with temperatures becoming
very hot by Thursday. Breezy conditions will also increase fire
danger for the end of the week. A dry cold front will bring
cooler temperatures for early next week.
&&
.SHORT TERM (Through 12Z/6AM Friday)...
Key Message: Hot temperatures on Thursday will challenge daily
records and push HeatRisk into the Major (level 3 of 4)
category along the Wasatch Front.
Generally quiescent conditions expected today as a flattened ridge
axis traverses the forecast area in the wake of a weak cold
frontal passage yesterday. Thus, temperatures today will start to
rebound to 5 to 8 degrees above average.
However, by Thursday, the ridge axis begins to amplify downstream
of the forecast area as a trough digs in toward the Pacific
Northwest coast later in the day. The result be a thermal ridge
axis centered over the region in the very dry southwesterly flow
aloft. This will allow temperatures on Thursday to soar another 10
degrees hotter than today (about 15-20 degrees above normal), and
challenge daily record values.
The forecast high of 102 at KSLC would break the daily record of
101 set in 1940, and there is about a 60-80% chance to tie or
break the record per calibrated ensemble guidance. While KSLC
records are easiest to track, many other locations across northern
Utah will challenge daily records, including Brigham City, Logan,
Ogden, Provo, Park City, and Alta. These forecast values track
well with the ECMWF Extreme Forecast Index across northern Utah,
where the values near 0.9 to 0.95 are near the top of the scale
(1) for max temperatures for this time of year on Thursday. All
this to say, there is fairly high confidence in anomalously hot
temperatures for this time of year on Thursday.
In terms of impacts, these hot daytime temperatures push the
HeatRisk into the Red/Major category (level 3 of 4) along the
Wasatch Front and westward to Tooele and Wendover. However, this
will be a fairly short-lived heat event with just one day of hot
temperatures not allowing for cumulative heat stresses to build
day after day. Considering all this, have issued a Heat Advisory
for Thursday, to highlight the elevated HeatRisk during the peak
daytime heat Thursday afternoon into the early evening.
.LONG TERM (After 12Z/6AM Friday)...
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...Clear conditions will last through the day with
light southeast winds transitioning to light northwest winds around
18Z.
.REST OF UTAH AND SOUTHWEST WYOMING...Clear conditions will last
through the day with light winds for most locations. Smoke from a
nearby wildfire will bring lowered visibility at KBCE through much
of the morning.
&&
.FIRE WEATHER...
Continued low RH across the region today, but with lighter winds
will result in a relative lull in the active fire weather
conditions across the state.
However, a warming trend will already be underway today, but
especially into Thursday as high pressure starts to setup to our
east while a low pressure system starts to move in along the
Pacific Coast. This will cause temperatures to soar to near daily
record values on Thursday in a very dry airmass. Southwesterly
winds will start to increase Thursday as well between the high and
low pressure system. This pattern will become stagnant through
Saturday with the area only continuing to be squeezed tighter
between the high and low pressure systems into Saturday, resulting
in increasing winds each day. By Friday there is a low chance
(30-50%) of exceeding 45 mph wind gusts across western and eastern
valleys, however, the strongest winds will peak by Saturday,
especially along and east of a line from Cedar City City to
Roosevelt into eastern Utah where there is a medium chance (>50%)
of gusts 45 mph or greater.
With the extremely dry airmass in place and elevated winds,
overnight recoveries will also be quite poor through this time
period, especially across southern and eastern Utah where values
may struggle to reach even 15% overnight in some locations.
Given the high confidence is critical fire weather conditions
over a prolonged period, and low to medium chance higher-end fire
weather conditions, have continued a Red Flag Warning across
numerous fire weather zones across Utah for Thursday through
Saturday.
A cold front is anticipated to push into the region by late
Saturday/ early Sunday, decreasing the overall threat of critical
fire weather conditions across the northern area. Depending on the
overall speed of this cold front and how far it progresses into
Utah, critical fire weather conditions may persist across far
southern and eastern Utah through Sunday (this is a generally low
confidence forecast).
&&
.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...Church
LONG TERM...Wilson
AVIATION...Wilson
FIRE WEATHER...Church
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity
