664
FXUS65 KSLC 110959
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
359 AM MDT Mon Aug 11 2025

.SYNOPSIS...A warming trend will continue today under a dry
northerly flow. High pressure will build overhead heading into
midweek maintaining the warming trend as temperatures become hot.
Moisture will slowly spread into the region beginning late
Wednesday, bringing a chance of thunderstorms through the latter
portion of the week.

&&

.SHORT TERM (Through 12Z/6AM Wednesday)...Dry and increasingly
hot conditions can be expected through the short term period
across the CWA.

Mid level ridging centered along the Pacific Coast early this
morning is inducing a dry northerly flow downstream across the
eastern Great Basin. This ridge will slowly build inland across
the Great Basin through the short term period. As it does so
temperatures will trend warmer each day, more notable across the
north where max temps will trend 3-5 degrees warmer today and run
near climo, before climbing another 2-4 degrees Tuesday. Further
south, a more muted warming trend of 1-3 degrees each day will
still be enough to bring St George to near 110F by Tuesday.

.LONG TERM (After 12Z/6AM Wednesday)...A hot airmass will remain
in place at the beginning of the long term period, as mid level
ridging becomes centered across the forecast area. Temperatures
will continue to trend 2-4 degrees warmer across northern Utah,
with KSLC likely reaching the 100F mark for the 6th time this
season (NBM 25th-75th percentile for max temp Wednesday is
99-101). Meanwhile max temps across central and southern Utah
will run closer to persistence on Wednesday.

As is fairly typical with strong mid level ridges in August,
mid level moisture will become entrained in this ridge by
Wednesday. This will bring a chance for high based convection
initially tied to the terrain during the afternoon, but
potentially spreading into adjacent valleys late in the day.
Strong microburst winds and isolated dry lightning are the primary
threats with any storms which develop, with only a minimal chance
for measurable precipitation.

This ridge axis will shift east by Thursday allowing for an
additional influx of moisture allowing PW values to exceed 0.5"
across the forecast area. Despite this, the boundary layer will
remain quite dry with dew points remaining below 40F Thursday
afternoon. As such, would anticipate in increased threat for dry
lightning across the state Thursday afternoon/evening with the
chance for measurable precipitation slowly increasing as the
afternoon/evening progresses owing to gradual moistening of the
boundary layer from top down.

Uncertainty in the forecast increases Friday through the weekend,
and largely centers around how long this moisture is able to
linger before being eroded under a general southwesterly flow
aloft. EPS members tend to favor keeping this moisture in place
heading into the weekend, and the longer residence time would
tend to favor a better chance for thunderstorms capable of
producing rainfall in excess of .10" over time. Meanwhile GEFS
members favor eroding this moisture a little more quickly,
favoring a drier weekend. Regardless, this influx moisture appears
to be temporary with the forecast trending drier toward the end of
the long term period.

With the ridge shifting east and the increase in moisture/cloud
cover during the latter portion of the week, max temps will trend
lower and return to near climo by Friday.

&&

.AVIATION...KSLC...VFR conditions prevail at the KSLC terminal
through the period, with mostly clear skies other than a few
passing high clouds this afternoon. Most likely scenario depicts
lake breeze (northwest) winds becoming established by 17Z,
although it is possible that occasionally light northerly winds
could develop as early as 12 or 13Z. Evening SSE drainage winds
expected to become established between 04-05Z this evening.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions prevail for
all regional terminals through the remainder of the period with
generally clear skies. Slight degradation in slantwise visibility
in the Uinta Basin this morning due to wildfire smoke. Winds will
largely be terrain-driven through the period.

&&

.FIRE WEATHER...High pressure centered near the Pacific Coast
is maintaining a dry northerly flow downstream across Utah.
As the airmass slowly modifies, temperatures will trend a
little warmer again today while the airmass remains very
dry. Although the winds will trend a little lighter today,
this northerly flow combined with a warm and dry airmass
will elevate fire weather conditions, particularly across
southern Utah east of I-15.

The upstream high will move overhead Tuesday, resulting in a
continued warming trend which will persist through Wednesday.
With this hot, dry and increasingly unstable airmass in place,
afternoon RH will fall below 15% across all elevations of
central and southern Utah, and northern Utah below 9000 feet.
This will be followed by a night of poor recovery Tuesday
night across most locations south of I-80.

By late Wednesday, moisture entraining into this high will
begin spreading into the area, resulting in a slight chance
of late afternoon high-based showers and dry Thunderstorms
mainly over the terrain. Moisture will continue to slowly
increase through Thursday, resulting in a better chance for
predominantly dry thunderstorms across much of the state.
This moisture looks to remain in place through at least
Friday maintaining a chance for showers and thunderstorms.
The chance for wetting rains will increase by Friday,
particularly across central and southern Utah. With the
increase in moisture, daytime RH will trend higher during
the latter portion of the week with improved overnight
recovery.

&&

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

$$

Seaman/ADeSmet

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