Office: SLC
FXUS65 KSLC 071034
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
334 AM MST Sun Dec 7 2025
.SYNOPSIS...Generally tranquil conditions are expected over Utah
and southwest Wyoming through Monday, with just a few showers late
Sunday into Monday morning near the Utah/Idaho border. Winds will
increase Tuesday into Wednesday, bringing the potential of strong
winds to southwest Wyoming and the western Uinta Basin. There is
25% chance that the northern Utah mountains will see warm
atmospheric river moisture return by midweek, with a 75% chance
that windy conditions will persist with minimal moisture.
&&
.SHORT TERM (Through 12Z/5AM MST Tuesday)...
Key Messages:
- High pressure will bring generally tranquil conditions across
Utah and southwest Wyoming through Monday
- Flow aloft will increase out of the west to northwest Tuesday
into Wednesday, with a medium chance of wind gusts exceeding 45
mph for southwest Wyoming and the Western Uinta Basin during
that time.
- There is a 25% chance that warm atmospheric river moisture
returns to northern Utah by Wednesday, which could produce 1-2
inches of water equivalent in the mountains with high snow
levels and dense snow. Otherwise, there is a 75% chance that
moisture remains to our north brining minimal precipitation and
otherwise windy conditions for the mountains.
Eastward expansion of the Pacific ridge has pushed atmospheric
river moisture and associated instability eastward out of Utah and
southwest Wyoming, resulting in tranquil conditions this morning
with just some high clouds for northern Utah. Temperatures will be
on the mild side, with maxes averaging 5F above seasonal normals
over southwest Wyoming and northern Utah, and up to 10F above
climo across southern Utah.
Grazing shortwave energy will bring an increase in cloud cover
over northern Utah this afternoon into Monday morning,
particularly near the Utah/Idaho border where there is a low
chance of light mountain snow. Any accumulations will be light.
Modest warm advection will bring a subtle warming trend,
particularly for northern Utah where maxes will approach 10F above
seasonal normals.
.LONG TERM (After 12Z/5AM MST Tuesday)...The mid-week storm continues
to be a tricky forecast as models struggle to pinpoint the
trajectory of a landfalling atmospheric river. QPF is the main
area of uncertainty by a long shot; in fact, QPF spread has
increased further across the northern mountains since earlier
forecasts.
But first, looking at the large-scale pattern, our forecast area
will be situated between a broad region of high pressure off of the
west coast and a trough across the eastern US by Tuesday morning,
resulting in overall northwesterly flow through at least Thursday. A
landfalling atmospheric river in the PacNW will bring moisture into
the Intermountain West, though the main question is how far south
it's able to reach. A reasonable low-end scenario puts only 0.00-
0.10" of QPF across the northern mountains, if that plume stays too
far north. However, model guidance has a fairly high tail in the
distribution, even at the 75th percentile. For example, the NBM 75th
percentile QPF between Tuesday and Thursday is up to 0.30-1.30"
across the northern mountains, with the highest amounts in the Bear
River Range.
Luckily, there is higher confidence in other aspects of the
forecast. For example, snow levels will be high, rising to 8000-
9000ft by Wednesday morning with subtle warm-air advection across
the area. This will result in very dense snow/low snow ratios,
similar to our even lower than our last storm system. Additionally,
regardless of what happens with precipitation, a strong jet to our
north will produce strong winds, particularly across Uinta Co., WY.
Current ensemble mean 700-mb flow is around 45kts, with guidance
suggesting wind gusts well into the 40-50kt range across much of the
county. NBM probabilities of 24-hour max gust exceeding 50kts reach
60-90% by Wednesday afternoon.
By Friday, conditions look to dry out statewide as the
aforementioned ridge builds across the western US. Temperatures will
hover around 10-20 degrees above normal, with 700-mb temperatures
rising to +2C to +5C by Saturday.
&&
.AVIATION...KSLC...Southerly to southeasterly winds will continue
through the TAF period, though will increase slightly to 8-12kts
between roughly 18-01z. VFR conditions will prevail, though CIGs
around 5000ft AGL will bring a period of mountain obscuration after
~06z Monday.
REST OF UTAH AND SOUTHWEST WYOMING...Conditions will remain largely
quiescent as winds continue to decrease across the area. Aside from
westerly wind gusts to 20kts developing SW-WY this afternoon, winds
should remain largely light and terrain-driven elsewhere. VFR
conditions will prevail, with lowering CIGs/mountain obscuration
heading into the evening hours, particularly after 03-06z. Expect a
few light showers to develop Sunday night across far northern UT.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
SHORT TERM...Traphagan
LONG TERM/AVIATION...Cunningham
For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecity
