387
FXUS65 KSLC 052008 CCA
AFDSLC

Area Forecast Discussion...CORRECTED
National Weather Service Salt Lake City UT
208 PM MDT Sat Sep 5 2026

.KEY MESSAGES...

- Gusty winds out of the southwest persist through at least Sunday
across much of Utah and southwest Wyoming, with an emphasis on areas
west of I-15.

- Tropical moisture advects north into Utah Sunday increasing
chances for precipitation.

- Threats for both flash flooding and isolated severe weather look
to develop on Sunday with the arrival of tropical moisture.

- The active upper air pattern continues into next week (50-60%
chance), potentially resulting in more precipitation by mid-week
following an early week lull.


&&

.DISCUSSION...Similar to yesterday, a large upper low continues to
slowly move into the Pacific NW, deepening with eastern extent. A
tight southwest-northeast oriented pressure gradient remains in
place across nearly all height levels resulting in another afternoon
of enhanced southwesterly flow overhead. With another clear and dry
afternoon where daytime surface heating is favorable, elevated winds
are forecast to mix to the surface yielding gusty conditions through
much of the afternoon statewide. Most areas across UT and SW WY can
once again expect to see gusts in the 25-35mph range, though areas
west of I-15 may see gusts approach (and potentially exceed) 45mph
given stronger winds aloft with higher surface temperatures to
encourage stronger mixing. This general pattern is expected to
continue into Sunday with enhanced afternoon southwesterlies
developing around the 10AM-12PM timeframe each day, though a slight
decrease in magnitude is expected Sunday given preceding cloud cover
which may inhibit mixing for areas east of I-15.

Come Sunday, moisture associated with Hurricane Marie is forecast to
phase into the mean upper flow as as the southern stream pushes
north and increases in magnitude. PWAT anomalies on the order of 0.5-
0.8 above seasonal normals (potentially exceeding 200% normal
values) are forecast to push north across much of Utah with this
increase in southwesterly flow. Widespread ascent will overspread as
the strengthening southern stream phases into the mean flow with the
aforementioned upper low, with a quick eastern progression of the
main precipitation axis through the afternoon hours. As such,
widespread showers and thunderstorms are forecast to develop in the
morning hours across much of southern and central UT, potentially
nudging into northern UT as well. Despite enhanced flow aloft
suggesting fast moving storms, robust moisture content within the
atmosphere continues to yield concern for flash flooding across
central and southern UT, where a slight risk (level 2/4) for
excessive rainfall has been outlined by the Weather Prediction
Center (WPC). Current guidance suggests hourly rainfall rates
ranging from 0.4-0.6"/hr, with some isolated rates nearing 0.6-
0.8"/hr rates possible.

Regarding the severe threat, it appears to have become more isolated
in nature given ample cloud cover from the morning hours into the
afternoon resulting in a stable layer across much of the state.
Ample shear exists on the order of 40-50kts, though only modest
buoyancy develops in the midst of persistent cloud cover and moist
boundary layer with robust convection likely struggling to develop
in the afternoon hours. If any stronger convection were to develop,
the most probable locations would be far northwest UT where
frontogenetic forcing is forecast to be strongest, and perhaps
southeast UT where a mid-level impulse is forecast to traverse in
the afternoon hours, particularly along Castle Country. The main
hazards will be isolated gusts to around 58mph and instances of sub-
severe hail less than 1".

Come Monday and Tuesday, the upper low progresses east leaving the
forecast area in a dry westerly flow regime keeping conditions calm
to start the week. On Wednesday, ensemble guidance has come to
better agreement with roughly 50-60% of all ensembles supporting
moisture return in some capacity to UT. However, all members within
cluster guidance support moisture return in some capacity through
the remainder of the week, resulting in timing being the only
uncertainty with this forecast rather than *if* moisture will
return.

&&

.AVIATION...

KSLC...Southerly winds will continue at the SLC terminal through the
day. Southerly winds will continue overnight, increasing once again
Sunday morning around 13-15Z.

REST OF UTAH AND SOUTHWEST WYOMING...Breezy southerly winds will
continue to impact most terminals through 02-03Z this evening. An
area of showers and embedded thunderstorms will move into far
southwestern Utah around 12Z and quickly shift north and east
through the morning. Expect occasional MVFR conditions in heavier
rain.

 &&

&&

.FIRE WEATHER...Moisture will continue to gradually increase into
sunday as southwesterly flow pushes moisture further north.
This afternoon, expect locally critical fire weather conditions
primarily across the West Desert and Great Salt Lake Desert where
humidities have been observed dropping below 15%. Additionally,
strong wind gusts across areas primarily west of I-15 will range
from 30-45mph each afternoon into Sunday.

On Sunday, a stronger push of moisture arrives to Utah with
widespread showers and thunderstorms across the state, though
primarily across central and southern Utah. The highest rainfall
totals are expected across higher terrain of central and southern
Utah, though lower elevation areas further east may see higher
isolated totals from stronger storms. For lower lying areas west of
I-15, generally a trace or less of precipitation is expected on
Sunday. A drying trend is expected to develop Monday and Tuesday
with more precipitation expected after midweek next week across at
least southern and central Utah.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch from Sunday morning through Sunday evening for
     UTZ113-114-116>120-122-124>128.

WY...None.
&&

$$

PUBLIC...Worster
AVIATION...Kruse
FIRE WEATHER...Worster

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