Snowbird, Utah Weather Forecast Discussion

938
FXUS65 KSLC 122120
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
320 PM MDT Fri Sep 12 2025
.SYNOPSIS...An upper level low gradually shifting east will maintain
unsettled weather through Saturday. High pressure briefly yields
quieter conditions Sunday, but another system and associated cold
front are expected to push through early in the upcoming week.
&&
.DISCUSSION...A large scale trough centered over the Great Basin and
gradually shifting eastward is serving as the dominant forecast
influence this afternoon. Currently the forecast area is sitting
within the stronger deep south to southwesterly flow regime ahead
of the trough. Strong jet support and PVA associated with the
trough has already helped produce some strong to severe early
morning storms across southeast Utah, and is continuing to aid in
a more volatile than typical environment in spots. Particularly,
this is noted across the eastern (and especially southeastern)
portions of Utah where mesoanalysis shows widespread bulk and
effective shear in excess of 50 kts, and CAPE values around
500-1000 J/kg. So far from late morning into the day convective
development has remained more focused near or east of the Green
River. That said, CAM guidance has continued to support some
increasing development from the Manti-La-Sal/Swell area northward
into the Uinta Basin/Mountains and southwest Wyoming. Given the
decent kinematics with the setup, any more robust updraft that can
get going will have potential to become strong to severe and
carry a risk of gusty winds and hail. While less impressive, will
also see some isolated showers and thunderstorms into the evening
across portions of northeast Utah where the core of the trough is
starting to move in. Expect coverage/intensity of activity across
the area to wane later in the evening on into the overnight hours.
Through Saturday the core of the large trough will slowly shift
through the area. This will bring a modest cooldown to much of the
forecast area, and help to maintain unsettled conditions
especially along and east of Utah`s high terrain during the
afternoon hours. Once again expect isolated to scattered
convection to develop and become more widespread as the day
progresses. While lapse rates may be a bit steeper given the the
trough being more overhead, the jet support will be quite a bit
lower than that of Friday. As such, expect some thunderstorm
development, but a lessened chance of more organized or robust
strong to severe weather. A few could produce periods of
moderately heavy rain and pose a threat to rain sensitive basins
though, so opted to maintain "Possible" ratings in the local Flash
Flood Potential Index for most rain sensitive recreation areas.
A transient shortwave ridge will slide into the region on Sunday.
In addition to helping temperatures rebound back upwards, it`ll
also help provide more stable conditions. As such, precipitation
chances are quite low Sunday.
This ridge will quickly begin to shift eastward late Sunday
evening into the overnight hours as a shortwave trough advances
from the PacNW. While the system looks to likely be more grazing
in nature, it`ll help to shove a cold frontal boundary southward
into the area Sunday night into the day Monday. Maintained low end
precipitation chances carried by the NBM, but ensemble guidance
continues to favor this cold front to largely be of the dry
variety, with only around 30% of members bringing some light
precip to northern Utah and southwest Wyoming. If nothing else
though, this will help cool temperatures a bit for areas behind
the front into Tuesday.
&&
.AVIATION...KSLC...VFR conditions will be maintained over the KSLC
terminal through the evening and overnight hours. Northerly winds
will persist through about 03Z, transitioning to a southerly flow
thereafter. There is about a 10% chance that another area of showers
move over/ near the airfield before 03Z. If this occurs, a period of
erratic flow will be expected with outflows.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected to
be maintained across a majority of the area through the evening and
overnight hours. Through the remainder of the evening MVFR to IFR
conditions will be possible in the northeastern portion of the CWA
from central Carbon County and Duchesne County eastward due to
visibility restrictions in heavy rainfall. Gusty winds in excess of
50 mph will be possible with these storms. All thunderstorm activity
is expected to conclude by 03Z, with overnight conditions remaining
largely dry alongside terrain driven winds.
&&
.FIRE WEATHER...The broad and slow moving system which has resulted
in showers and thunderstorms across eastern Utah on Friday will
provide one more day of unsettled conditions Saturday. Once again
anticipate showers and thunderstorms to begin to develop by late
morning to early afternoon, with scattered activity becoming a bit
more widespread through the afternoon hours. This activity will
once again be favored at areas generally along and east of Utah`s
high terrain, with coverage and strength then waning through the
evening hours.
After a quieter day Sunday courtesy of a brief period of high
pressure, another more grazing type system will push a cold front
southward into Utah Sunday night into the day Monday. This is
favored to be a dry cold front, with only around 30% of models
carrying light precipitation to portions of northern Utah.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
PUBLIC...Warthen
AVIATION...Webber
FIRE WEATHER...Warthen
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

NWS SLC Office Area Forecast Discussion