345
FXUS65 KSLC 031709
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1109 AM MDT Thu Sep 3 2026

.KEY MESSAGES, Issued 1001 PM MDT Wed Sep 2 2026...


- Gusty southwest winds are expected each afternoon and evening
  across Utah and southwest Wyoming through the end of the work
  week. With minimum relative humidities approaching critical
  values in pockets of western Utah, this will result in some
  locally critical fire weather conditions.

- An influx of tropical moisture over the holiday weekend will
  increase the risk of flash flooding into early next week,
  particularly on Sunday across central and southern Utah.

&&

.DISCUSSION, Issued 1001 PM MDT Wed Sep 2 2026...
Utah and southwest Wyoming remain sandwiched in
between an upper low off the Pacific Northwest coast and a broad
ridge over the central United States. This has resulted in a
persistent breezy southwesterly flow that is advecting drier air
into the area. Thursday is anticipated to be the driest day for
the region, with minimum relative humidity values approaching
critically low values for portions of western Utah, the northwest
desert in particular. This will likely result in some locally
critical fire weather conditions during the afternoon, but given
the improvement in fuels from recent rains, the fire danger is not
as high as it could be. The airmass over the area will stay just a
bit on the cool side, with maxes running near to up to 5F below
seasonal normals through the end of the work week.

As we enter the holiday weekend, all eyes will turn to the eastern
Pacific where Hurricane Marie is currently tracking westward away
from Mexico. Guidance continues to indicate that the southerly
flow will tap into deep tropical moisture from the system,
bringing that moisture up through Utah and southwest Wyoming by
Sunday. This influx of moisture will bring the return of fairly
widespread coverage of showers and thunderstorms, with any storms
that develop capable of producing heavy rain that could lead to
flash flooding.

There remains lower confidence than usual in the timing of the
arrival of this moisture and its trajectory, as this is dependent
on the precise track of Marie, something that global models can
struggle with, and also the trough currently over the Pacific
Northwest. The prevailing thought is that the system will spin
just off the coast through the first part of the weekend before
eventually grazing northern Utah early next week. Its passage is
expected to give a more westerly component to the flow, cutting
off the tropical moisture and bringing drier air back in. However,
there remains disagreement as to when it will graze the area, and
how far south the system will actually get. Hopefully details will
become a bit clearer over the next few days.





&&

.AVIATION...

KSLC...Surface winds are expected to ramp up over the next 1-2hrs
with enhanced southerlies persisting into tomorrow at the KSLC
terminal. Gusts out of the south up to 30kts are possible this
afternoon, though higher probabilities exist tomorrow of reaching
30kts. Sustained winds out of the south are expected to range from
15-20kts. Otherwise, VFR conditions are expected to persist through
the TAF period.

REST OF UTAH AND SOUTHWEST WYOMING...Enhanced south/southwesterly
winds are forecast to develop across all TAF sites through the
period. KLGU and our southern UT sites will see the highest wind
gusts from this, potentially in excess of 30kts in the afternoon
hours. Due to the strength of this system, winds will remain
south/southwesterly through the duration of the TAF period. However,
VFR conditions will persist otherwise across all terminals.

&&

.FIRE WEATHER, Issued 433 AM MDT Thu Sep 3 2026...
Windy conditions are expected to resume today across much
of Utah alongside continued low afternoon humidity values,
especially across western Utah. With only marginal improvements to
daytime relative humidity, strong winds will pair with this dry
environment to create another day of locally critical fire weather
conditions in western Utah, especially for areas that did not
receive a sufficient amount of rainfall over the past week. Areas
across the eastern half of Utah are expected to see a more
noteworthy drop in relative humidity as compared to yesterday
(about 5-10 percent lower) but still remaining above, or right
around, critically dry thresholds (15 percent).

Moisture is expected to increase late in the week and through the
weekend, bringing improvements to humidity values areawide. While
overall moisture in the atmosphere will rise through the weekend,
shower and thunderstorm activity is expected to be meager at best
on Friday and Saturday, with coverage being limited to high
terrain features in the southern Utah mountains. That said, a more
significant push of moisture is anticipated to inundate the
region by Sunday, bringing much greater coverage of showers and
thunderstorms capable of producing wetting rains. A weak cold
front may graze northern Utah late Monday/ Tuesday, bringing
potential to shunt moisture out of Utah. Beyond early next week,
the forecast becomes more uncertain.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...Red Flag Warning until 9 PM MDT this evening for WYZ277.

&&

$$

PUBLIC...Traphagan
AVIATION...Worster
FIRE WEATHER...Webber

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