477
FXUS65 KSLC 010306
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
906 PM MDT Sat Oct 31 2026

.KEY MESSAGES...

- There is a Moderate Risk for Excessive Rainfall (level 3 of 4)
  across portions of southern Utah, as a surge of moisture brings
  widespread rainfall across the region. A Flood Watch is in
  effect for much of southern and east central Utah late tonight
  through Sunday evening.

- Accumulating mountain snow is expected across all Utah
  mountains Sunday through Monday morning. Upwards of 12" of snow
  is expected above 9000 feet, and 3-6" of snow down to around
  7000 feet. Upper elevations of the Cottonwoods and western
  Uintas may see localized accumulations 18-24".

- Cool, dry, and stable conditions will temporarily build in
  Tuesday, with another weak storm system expected during the
  Wendesday-Thursday timeframe.

&&

.DISCUSSION...

An inland-penetrating Atmospheric River (AR) coupled with a deep
upper trough spreading into the Great Basin later tonight through
Sunday will bring widespread rain and high elevation snow to the
forecast area over the next 36 hours. This AR is currently making
landfall with widespread precipitation quickly spreading across
the lower deserts of southern CA and AZ. This moisture will
quickly spread across the forecast area from south to north
overnight, and persist through Sunday morning.

The forecast has remained fairly consistent over the past couple
of days, with locally upwards of 3" of additional rain across
orographically favored areas of southern Utah from the Pine
Valleys east to Boulder Mountain, and 1+ inches of rain in lower
elevations including St George, Cedar City, Zion Canyon and Kanab.
Given recent rainfall over the past few weeks, antecedent
conditions are nearly saturated and runoff is expected to be very
efficient, resulting in another round of flooding across southern
and east central Utah beginning late tonight, and continuing
through Sunday.

As the region of enhanced IVT shifts east of the forecast area
Sunday afternoon, the upstream trough will spread into the Great
Basin, with increasing large scale ascent interacting with an
already saturated airmass to maintain widespread precipitation
through the afternoon and into the evening. Cooling temperatures
aloft will begin lowering snow levels from west to east during the
afternoon, with snow levels falling below 8000 feet by late Sunday
evening across nearly the entire forecast area excluding the far
southeast. As this trough progresses into the central Rockies, a
favorable period of post-frontal orographics looks to persist
along the I-15 corridor through Sunday night, before gradually
winding down Monday morning. Total snow accumulation looks to run
in the 3-6" range below 9000 feet, while higher elevations will be
pushing 12"+, and perhaps upwards of 20" in the upper Cottonwoods.
Low elevation rainfall totals will likely exceed 1" across most
northern valleys including much of the Wasatch Front through
Monday morning.

Mid level ridging will bring temporary dry and stable conditions
late Monday through Tuesday, with a more progressive wave forecast
to translate through the region Wednesday into Thursday. This
quick-hitting wave will lack the moisture tap of recent events,
thus precipitation totals will remain fairly light. Long range
models lean heavily toward longwave ridging building into the
region next weekend into early in the following week.


&&

.HYDROLOGY, Issued 1012 PM MDT Fri Oct 30 2026...
Through Sunday night, Issued 1012 PM MDT Fri Oct 30 2026...
additional rainfall, locally
heavy across southern Utah, will once again bring elevated
potential for localized flash flooding and widespread rises to
area waterways in southern and portions of central Utah. The most
significant period of precipitation is expected on Sunday.

Earlier precipitation brought areas of flooding to portions of
southwest Utah. However, coverage has decreased this evening. A
relative downtick in heavy rain potential exists for Saturday, but
the primary precipitation producer will be moving into the area
Sunday. The broad upper trough off the Pac Coast is expected to
phase with a strong short wave embedded within a strengthening
southern tier jet. Anticipated set-up will allow a land falling
atmospheric river (AR) to penetrate inland into southern/central
Utah producing widespread moderate to locally heavy rainfall
across the Arizona strip, Grand Staircase, and southern/central
mountain regions, including National Parks and Recreation Areas
within these areas. Rainfall amounts of 1-2.5" are likely with
this, and given antecedent conditions, will efficiently runoff the
landscape promoting widespread rises for all waterways, including
streams, creeks, normally dry washes, slot canyons, and rivers
across the region.



&&

.AVIATION...

KSLC...Occasional rain showers will pass over the terminal
through the evening with VFR conditions persisting. Widespread
rain will develop around 08Z, and persist overnight and through
the day Sunday, resulting in predominant MVFR conditions with
brief periods of IFR possible within heavier precipitation.
Southerly winds will largely prevail overnight through Sunday
morning, but may become light and variable at times after 12z.
Winds will transition to northwesterly between 20-22z as a cold
front passes through the terminal.

REST OF UTAH AND SOUTHWEST WYOMING...Rain spreading across the
entire area after 06Z tonight will bring widespread MVFR to
locally IFR conditions overnight through much of the day Sunday.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory until 11 AM MDT Monday for UTZ111-112.

     Flood Watch from 5 AM MDT Sunday through Sunday evening for
     UTZ120-121-123>125-127>131.

WY...None.
&&

$$

Seaman

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