749
FXUS65 KSLC 240935
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
335 AM MDT Sun Aug 24 2025

.SYNOPSIS...High pressure will continue to draw monsoon moisture
north into Utah and southwest Wyoming through the middle of the
upcoming week. This will bring increased coverage of showers and
thunderstorms, the potential for flash flooding, and gradually
less hot temperatures. Conditions will gradually dry for the
latter half of the week.

&&

.SHORT TERM (Through 12Z/6AM Tuesday)...Seeing a classic monsoon
set up across the region this morning, with high pressure centered
over the Four Corners and southerly flow over Utah and southwest
Wyoming. Satellite derived PWs are currently in the 1.0 to 1.2
inch range everywhere except far northeast Utah and southwest
Wyoming, which show values in the 0.8 to 1.0 range. With ample
moisture in place, seeing some areas of showers continue
overnight, primarily over west central Utah in association with a
weak ejecting shortwave. This feature is expected to continue to
northeast during the day, making northern Utah the focus for
convection for the late morning into the early afternoon.

Seeing another weaker shortwave in the vicinity of southeast Utah,
bringing some thicker cloud cover as well as a few showers. Given
the higher level of moisture down there and some expected
subsidence from the northern wave, convection should be more
widespread over central and southern Utah this afternoon, per
guidance. Potential limiting factor will be the current cloud
cover, particularly for southeast Utah, as guidance tends to be a
bit optimistic about cloud cover eroding in these situations. If
the clouds diminish as expected, convection could become
widespread across southern Utah with heavy rain capable of flash
flooding likely with any storms that develop. Thus, the flash
flood potential is in the probable range for the southern Utah
national parks today.

The focus of convection during the evening and overnight shifts
back to northern portions of the area, with additional shortwave
energy providing instability. By the afternoon, the high is
expected to wobble west a bit, with the axis overhead by late
afternoon. Guidance indicates a relative absence of shortwaves
during this period, so convection will be focused over the higher
terrain. Some drift is expected, but will be limited by the lack
of steering flow aloft. Still, given the moisture rich airmass,
coverage should be fairly widespread across the area.

.LONG TERM (After 12Z/6AM Tuesday)...By early Tuesday the mid level
ridge axis will be centered across the southern Plains, allowing for
a deep layer southerly flow extending from the Baja region through
the Desert Southwest and into the eastern Great Basin. This flow
will continue to maintain a fairly robust monsoon airmass across the
forecast area with widespread PW values in excess of 1" and surface
dew points in the 50s across low-mid elevations. Model guidance has
been indicating a weak wave within this flow will lift through the
region during the day Tuesday, enhancing lift and resulting in
fairly widespread precipitation across the forecast area. How much
surface heating and subsequently the degree of instability available
Tuesday will determine the heavy rain threat, but with the amount of
available moisture any thunderstorms which do develop will be
capable of heavy rainfall Tuesday afternoon and evening.

By Wednesday, in the wake of this wave, low level flow will veer to
westerly allowing for the beginning of a drying trend. As is often
the case as the airmass being to dry, increased solar heating
coupled with ample lingering moisture may actually result in a bigger
heavy rain/flash flood day Wednesday afternoon and evening.

Owing to widespread cloud cover and precipitation daytime
temperatures Tuesday and Wednesday will run 7-10F below climo,
potentially struggling to reach the low 80s along the Wasatch Front
as well as most western and central valleys, while the St
George/Zion Canyon area remains in the low 90s.

A more westerly flow will become established for the latter portion
of the upcoming week, which will work to gradually erode the
monsoonal airmass. Lingering moisture will maintain showers and
thunderstorms, however coverage will decrease Thursday into Friday.
With the decrease in moisture temperatures are forecast to trend
slightly upward heading into next weekend.

This drying trend will continue through the end of the week as mid
level ridging begins to amplify across the Great Basin. This will
allow for a gradual warming trend heading into the upcoming holiday
weekend, with lingering moisture maintaining a reduced chance of
mainly terrain driven convection.

&&

.AVIATION...KSLC...The terminal will remain on the northern fringe
of an area of moisture spreading into northern Utah this morning. As
such on occasional shower or two is possible through the morning
with VFR conditions prevailing. There is a 10-15 percent chance of a
thunderstorm producing lightning and gusty winds in the vicinity of
the terminal between 16-19Z. Conditions will improve through much of
the afternoon. Southerly winds will prevail this morning, turning to
the northwest by 19Z. However passing showers this morning may
result in variable wind directions at times.

.REST OF UTAH AND SOUTHWEST WYOMING...Afternoon showers and
thunderstorms will again develop across much of the region this
afternoon, which may impact area terminals with gusty outflow winds,
lightning, and brief MVFR visibility within heavier rainfall. Away
from these storms, VFR conditions with terrain driven winds can be
expected.

&&

.FIRE WEATHER...Deep moisture will continue to make its way into
Utah during the early part of the week. As a result, coverage of
showers and thunderstorms will increase, particularly during the
afternoon and evening, with increasing relative humidity values
and decent chances of wetting rains. Temperatures will become less
warm, up to 10F below seasonal normals by midweek, with winds
staying light and terrain driven away from thunderstorms. The
airmass will start to dry for the latter half of the upcoming
week.

&&

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

$$

SHORT TERM/FIRE WEATHER...Traphagan
LONG TERM/AVIATION...Seaman

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