514
FXUS65 KSLC 262101
AFDSLC
Area Forecast Discussion
National Weather Service Salt Lake City UT
301 PM MDT Sat Apr 26 2025
.SYNOPSIS...An expansive cutoff low will push through Sunday and
Monday, bringing fairly low elevation valley rains and late season
mountain snowfall. A progressive and unsettled pattern then looks to
continue into the upcoming week.
&&
.SHORT TERM (Through 12Z/6AM Tuesday)...A large cutoff low
churning onto the central California coast can be easily
identified via satellite water vapor loop this afternoon. Ahead of
it, seeing some mid to high level cloud cover filtering through,
but for today area radars remain quiet. With H7 temps running
about +3C to +7C, temps across the area are pleasantly mild.
Afternoon highs at most low elevation valleys will end up in the
70s, and at higher elevation mountain valleys more in the 60s.
With increasing H7 flow nosing in overhead with the approaching
low, seeing some correspondingly gusty conditions mixing down,
with gusts generally in the 20-35 mph range across the northern
half of the area, and 30-45 mph range at areas further south.
With these gusts, anticipate some blowing dust in areas downstream
of an associated dust source.
After a fairly quiet night, moisture will increase on Sunday as
the cutoff low approaches the NV/UT border. Shower chances
increase through the day accordingly, and with sufficient low end
destabilization in the afternoon, a few thunderstorms will also be
a possibility. Sunday night into Monday the core of the broad
system will shift eastward and become more centered atop Utah.
Precipitation chances will be maximized closer to this
circulation, especially in areas placed in something a deformation
zone as the low continues to slowly pivot through. As the day
progresses the low`s motion will allow flow to trend more
northerly, and in turn continued showery precipitation will be
likely, with steepened lapse rates likely to allow for some
convective components as well. Precipitation will gradually taper
off late Monday evening on through the overnight hours as dry air
and subsidence increases.
Given the cutoff nature of the low and how late in the season it
is, the airmass isn`t overly cold, and H7 temps will gradually
fall into the -2C to -5C range as the low moves overhead. In
combination with the precipitation and cloud cover, afternoon
highs will fall quite a bit, back to the colder side of
climatological normal for late April. Snow levels look to sit in
the 6000-6500 ft MSL range for much of the event, which will allow
for valley rain and mountain snow. With lower freezing levels
given the cooler airmass overhead though, could see any slightly
stronger convective type of activity produce some lower elevation
graupel. It does appear a cool enough system to result in some
generally light mountain snow accumulations though. Current
forecast carries a rough 2-5" for areas above 8500 ft or so, and
more in the T-2" range for areas above 7000 ft or so. Best
accumulations look to favor the northern mountains, particularly
the upper Cottonwoods and western Uintas, and some locally higher
amounts up to 7" or so are noted accordingly.
.LONG TERM (AFTER 12Z TUESDAY)...At the beginning of the long term
forecast period, shortwave ridging will begin to build back into
Utah from the north, while the previous storm system, now a
positively-tilted, elongated trough, continues to slowly shift
southeast. While a few showers remain possible on Tuesday, expect
generally drier conditions along with a warming trend that will
bring temperatures closer to seasonal normals.
The shortwave ridging will be short-lived, as it will make way for
the next weather disturbance on Wednesday. This will feature a
splitting trough that will bring some moisture in from the north
behind a modest cold front, but otherwise generally weak dynamics.
Heading into Thursday, global deterministic models leave a
deformation/shear axis across Utah between the resulting closed low
somewhere over California or the desert southwest and the northern
branch trough which will be moving into the Great Plains and
Midwest. Even with some uncertainty in the large-scale pattern, this
would suggest some unsettled weather will remain in place over the
forecast area.
Thereafter, the closed low is expected to weaken and eject into Utah
late week or over the weekend, this ahead of the next upper trough
moving into the PacNW. Some timing issues still need to be worked
out, but this pattern would suggest warmer temperatures and
increased southerly flow ahead of increasing precipitation.
&&
.AVIATION...KSLC...Gusty southerly winds will continue through this
afternoon and early evening at KSLC. A transition to west-northwest
is possible for a brief window following 02z, switching lighter out
of the southeast thereafter. Southerly winds increase again after
16z Sunday as a cold front tracks through the region. Rain showers
are expected to accompany this frontal passage, with chances for
these showers impact the terminal after 18z.
.REST OF UTAH AND SOUTHWEST WYOMING...Gusty southerly winds (20-25+
kts) will continue across most regional terminals today ahead of an
incoming weather system. Winds decrease across the northern half of
the airspace this afternoon, with gusty winds persisting overnight
and into Sunday across southern Utah. Gusty southerly winds
redevelop areawide late Sunday morning as a cold front tracks
through the region, with precipitation chances increasing behind the
front on Sunday afternoon.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
SHORT TERM...Warthen
LONG TERM...Cheng
AVIATION...Whitlam
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity
