566
FXUS65 KSLC 281931
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
131 PM MDT Mon Sep 28 2026

.KEY MESSAGES, Issued 1139 AM MDT Mon Sep 28 2026...


- A moderate risk (level 3/4) for excessive rainfall has been
  issued for southern Utah today. A slight risk (level 2/4) for
  excessive rainfall is in effect for the remainder of southern
  and eastern Utah today.

- A slight risk (level 2/4) for excessive rainfall is in effect
  for southern Utah Tuesday.

- A Flood Watch for flash flooding has been issued for portions
  of central and southern Utah through Tuesday morning, with far
  southern Utah in effect through Tuesday night.

&&

.DISCUSSION, Issued 1139 AM MDT Mon Sep 28 2026...
A late season surge of monsoon moisture, enhanced
by the remnants of post-tropical cyclone Odalys and to a lesser
extent hurricane Polo, has spread across the Desert Southwest
ahead of a closed low digging through central CA. Deep
southwesterly flow has pulled this moisture northward across much
of Utah this morning, where satellite-derived PW values and
observed soundings indicate values in excess of 0.75" across much
of Utah, with values near or above 1" across southwest Utah.
These values range from 150-200% of normal for late September.
With this moisture in place, a moderate risk for excessive
rainfall remains across southern Utah, with a slight risk
extending into central and northeastern Utah, and a marginal risk
across the remainder of the state. A Flood Watch remains in
effect for much of central and southern Utah through tonight, and
through Tuesday evening across far southern Utah.

Broad large scale ascent within a region of large scale diffluence
downstream from the upper low is spreading across much of eastern
NV/western UT late this morning, with breaks in the cloud cover
allowing for an increase in instability and a considerable
increase in convection over the past hour or so. Given the ample
moisture available, this convection will be capable of producing
heavy rainfall with very efficient rainfall processes. Expect this
convection to spread/increase across central and southern Utah
through the afternoon hours. As the upstream low continues south,
model guidance suggests a mid level deformation axis sets up from
central into southwest Utah later this evening through tonight,
which should serve as a focus for persistent precipitation, which
should transition from convective to more of a stratiform nature
later this evening through tonight.

The upper low will progress through the Desert Southwest on
Tuesday, maintaining an anomalously moist airmass across southern
Utah where the potential for heavy rainfall will persist.
Meanwhile, to the north of this low a cool and stable airmass will
settle across northern and central Utah as mid level heights and
resultant subsidence bring an end to the chance for widespread
organized precip, with perhaps a few lingering showers mainly over
the terrain.

For the remainder of the forecast period, model guidance has been
very consistent in building a longwave ridge across much of the
west through the latter portion of the week into the upcoming
weekend. This will result in a warming and drying trend, which
will likely persist into next week. Temperatures will return to
near climo by Thursday across the area, then slightly above normal
by Friday as this warming trend persists. A weak shortwave
passing well east of the forecast area may bring a slight cooling
trend to northern and eastern portions of the forecast area
Saturday, but in general warm and dry conditions can be expected
heading into the first full week of October.



&&

.AVIATION, Issued 1139 AM MDT Mon Sep 28 2026...


KSLC...Chances for showers and thunderstorms at the terminal
remain elevated through 00z this evening, gradually tapering off
through 08z as a cold front pushes through. Following this, winds
will remain elevated out of the northwest through much of
tomorrow, with gusts up to 20kts in the afternoon with VFR
conditions prevailing.

REST OF UTAH AND SOUTHWEST WYOMING...Chances for showers and
thunderstorms remain elevated across all TAF sites through 24z,
then gradually tapering off through 08z, though KICX and KSGU will
see chances for showers continue. A cold front will sweep through
much of the area, resulting in VFR conditions with enhanced NW
flow across all northern UT and SW WY sites after roughly 12z.
KCDC and KSGU will see chances for showers and thunderstorms carry
in through much of tomorrow, with MVFR CIGs developing as well as
a system moves out of the region.

&&

.FIRE WEATHER...Tropical moisture being pulled northward into
the region will bring widespread showers and thunderstorms
through tonight. Wetting rains are likely across all areas,
with locally heavy rainfall resulting in flash flooding
expected across central and southern Utah. This is in
association with a low pressure system making its way through
the region. A cool and more stable airmass will settle into
northern Utah Tuesday behind this system, while lingering
moisture maintains a chance for heavy rain across southern
Utah. The pattern will shift towards a warmer and drier regime
for the latter portion of the week, as a broad area of high
pressure becomes established across the region. This high will
maintain a warm and dry airmass through the weekend, and
likely through much of next week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch through late tonight for UTZ113-115>122-125>127.

     Flood Watch through Tuesday evening for UTZ123-124-128>131.

WY...None.
&&

$$

PUBLIC...Seaman
AVIATION...Worster
FIRE WEATHER...Seaman

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