Alta

000
FXUS65 KSLC 312015
AFDSLC

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

.KEY MESSAGES...

- A lull in activity continues through early this evening ahead of 
an incoming system. 

- A strong moisture push is expected late tonight with chances for 
rain increasing across the forecast area into tomorrow. Widespread 
light to moderate rainfall is expected tomorrow, with isolated 
instances of heavier rainfall rates possible across southwest Utah. 

- Accumulating mountain snow is expected across all Utah mountains 
through Monday morning. Given high snow levels, 3-6" of snow is 
expected for most mountains. However, the Upper Cottonwoods and 
western Uintas may see localized accumulations 18-24" above 10000ft. 

- Cool, dry, and stable conditions build in Tuesday following the 
passage of this system. Ensembles hint at an active period 
developing again later next week. 

&&

.DISCUSSION... Currently, a deepening mid-level trough is situated 
off the western U.S. coastline with broad southwesterly flow 
persisting across the Desert Southwest. Deeper moisture has been 
analyzed further south near the Baja Peninsula, southern CA, and 
southern AZ this afternoon with drier conditions further north, 
though some moisture currently exists across the forecast area with 
PWATs ranging from 0.6-0.8. Later this afternoon, a weak mid-level 
trough will traverse across UT providing modest ascent resulting in 
isolated to widely scattered showers and thunderstorms across the 
state, particularly across southwest UT. Storm motions ranging from 
25-30kts from the southwest amidst lower PWATs generally preclude 
most flooding concerns today, though some localized nuisance 
flooding may be possible if storms track over already saturated 
locations given how wet it has been as of late. 

Later this evening into tomorrow morning, the mid-level trough will 
deepen markedly and become negatively tilted as it interacts with a 
southern stream impulse further south. This will strengthen ascent 
across the forecast area with increasing PoPs areawide as a result. 
While this event is forecast to be a longer duration light to 
moderate stratiform rainfall event, rainfall totals raise concern 
given already saturated soils across much of the state. For most 
valley locations, 25th percentile amounts range from 0.75-1.25" with 
most mountains, southwest UT, and the Wasatch seeing 25th percentile 
amounts ranging from 1.50-2.00". For 75th percentile amounts, this 
increases notably for lower elevation locations with a range of 1.50-
2.00", and 2.50-3.00" for all specific aforementioned locations. 
While spread remains high, we must acknowledge that even the lower 
range of these rainfall amounts are rather high and could still 
result in areal flooding.

On Sunday night, a cold front will sweep across the area serving to 
put an end to most lower elevation precipitation. However, elevated 
moisture remains in place amidst northwest flow following the front, 
resulting in widespread mountain snowfall across the entire forecast 
area. For areas above 8000ft, around 3-6" of snowfall is expected 
from this system. Further north, primarily concerning the 
Cottonwoods and western Uintas above 10000ft, totals will range from 
18-24" given northwest flow amidst ample moisture remaining in 
place. 

On Monday, transient ridging builds in the wake of the departing 
system bringing cool, dry, and stable conditions to the forecast 
area. Another trough looks to impact the region mid-week bringing 
another stretch of unsettled weather, though spread remains high at 
this time making it difficult to iron out specific impacts. 

&&

.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...Southerly winds prevail through the day today into Sunday as 
a storm system approaches the area. Isolated and generally light 
rain showers will be possible at the terminal through this evening. 
Showers may bring brief CIG reductions below 6000 feet through this 
afternoon; otherwise, VFR conditions are likely to persist through 
this evening. More widespread light to moderate rainfall moves into 
the area after roughly 05z, with CIGS/VIS lowering into MVFR 
categories as rain fills into the Salt Lake Valley. Expect these 
conditions to continue into Sunday as steady rain lingers.

REST OF UTAH AND SOUTHWEST WYOMING...Isolated showers across 
northern Utah/southwest Wyoming and scattered showers across 
southern Utah will bring mountain obscurations and localized reduced 
visibilities through this afternoon. As the next storm system brings 
deeper moisture into the area, precipitation will become more 
widespread and heavier late this evening through the overnight 
hours, generally after 04-06z across the entire airspace. Expect 
deteriorating conditions through this timeframe, with an increasing 
likelihood of MVFR conditions at most TAF sites along with mountain 
obscurations. 

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory from 9 PM this evening to 11 AM MDT 
     Monday for UTZ111-112.

     Flood Watch from late tonight through Sunday evening for UTZ120-
     121-123>125-127>131.

WY...None.
&&

$$

PUBLIC...Worster
AVIATION...Whitlam
HYDROLOGY...Merrill

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