An atmospheric river event brought mountain snow throughout Utah, especially the southern mountains.
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The episode as NWS SLC wrote it up.
An atmospheric river event brought mountain snow throughout Utah, especially the southern mountains.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Salt Lake City, UT wrote its last area forecast discussion before the first event at Jan 31, 4:28 PM MST, 7 hours 32 minutes earlier.
Area Forecast Discussion
National Weather Service Salt Lake City UT
428 PM MST Wed Jan 31 2024
.SYNOPSIS...A Pacific storm begins to move into the region Thursday,
bringing about a pattern shift to wetter and cooler conditions.
This storm will bring widespread mountain snow accumulations, with
periods of generally valley rain through early Sunday. A second
Pacific storm then looks to move into the area by early next week.
&&
.SHORT TERM (Through 00Z Saturday)...Persistent ridge as of late is
beginning to slip eastward as a strong Pacific trough churns
closer to the coast. GOES-WV imagery shows that while dry air
currently remains over most of Utah, impressive moisture plume
associated with the Pacific trough is inching closer through the
Great Basin. That said, with the exception of some sheltered
valleys like the Cache Valley, many locations across the forecast
region are seeing very mild temperatures as stronger southerly
winds have helped to break down the lingering inversions. To that
point, seeing several locations flirting with record high marks
for the day.
favorable south/southwesterly IVT/moisture fetch begins to
overspread the region overnight into Thursday as the Pacific
trough continues its inland trajectory. Will see precipitation
chances initially increase across the southern mountains Thursday
morning, with elevated precipitation chances then continuing to
spread south to north through the day, enveloping more or less the
entirety of the forecast region. Given some of the higher
momentum air (700mb flow ~25-40 kts) available, and some forecast
soundings initially showing potential for some convective elements
to precipitation Thursday afternoon, wouldn't rule out some
moderate gusts mixing to the surface with precipitation onset. As
a whole, best chances of this look to be across western to
southwestern Utah. Given the initially mild nature of the system,
will see snow levels through Thursday generally remain above 7000
feet, promoting accumulating mountain snow, and lower elevation
valley rain.
Overnight Thursday into the day Friday, will see cold air
advection start to set in (though deep layer flow will still
largely remain south to southwesterly), and falling snow levels.
Will see snow levels gradually fall to around 6000-7000 feet by
Friday morning, with further decreases to around 5500-6500 feet by
later in the day.
During the Thursday into Thursday night time frame, the strong
southerly upslope flow will likely result in the strongest period
of accumulation for the southern mountains. Will still see more
modest accumulation continue into Friday, but during Friday will
start to see better rates/accumulation spread further into the
central and northern mountains as the aforementioned cold air
advection increases.
Overall, forecast snow accumulation and SWE numbers (as well as
general timing) have changed minimally with this forecast package,
so opted to maintain current winter headlines as is (including
those that fall in the subsequent long term forecast).
.LONG TERM (After 00Z Saturday)...Moving into the latter portion of
a prolonged winter storm on Friday night, will see a few key changes
as the trough axis moves in overhead and large-scale flow
transitions from predominant southerlies to west/northwesterlies.
While agreement is good across the ensemble suite, there a few
nuances that will impact the outcomes in the forecast in critical
locations including the northern mountains and population centers
including the Wasatch Front and Cache Valley. While the higher-
probability outcome (represented in the current forecast grids)
would moderate precipitation totals and higher snow levels under a
combination of warming/downsloping into the Salt Lake and Cache
Valleys and increasing subsidence aloft, a colder and faster
scenario with earlier transition to northwesterly flow before drying
sets in would lead to the potential for low-impact, but non-
negligible snow accumulation along the Wasatch Front and Cache.
Saturday through Sunday - and exacerbated impacts for mountain
passes and higher elevation locations.
After a period of transient ridging, the second low pressure system
will shift onshore, with ensemble means driving the feature up
through southern California and western Arizona, setting up a potent
southerly flow scenario. Spread between the 10th-90th percentile
PQPF across southern Utah's mountains and the upper portions of the
Grand Staircase/Escalante is quite tight, less than 0.25" in most
areas with total accumulations centered around 1" for the most
favored areas (especially Brian Head). However, given the nuances of
timing and duration of the flow shifting from south to west, much
greater uncertainty exists across northern and central Utah's
mountains.
A few areas to watch through the duration of both events remains the
Manti Skyline, Southern Uintas, western Uinta Basin, and the
eastern valleys. EMCWF EPS EFI highlights these areas as having
elevated potential for climatologically anomalous precipitation (and
less so but still worth noting, anomalous snowfall) throughout both
of these distinct events. While raw QPF numbers may not seem
impressive, these areas are usually shadowed in typical cool-season
flow regimes and have the potential to tally up a significant
portion of their seasonal precipitation in a short duration of time
over the next 7 days. Along with modest 3-hourly precipitation
rates, snow levels at this time remain in tight spread and low
enough in elevation at this time to keep isolated flooding in these
areas a very minor concern - but still worth mentioning for
awareness.
&&
.AVIATION...KSLC...VFR conditions are anticipated throughout the
forecast. High based clouds are forecast this evening and into
tomorrow with the arrival of mid layer clouds by tomorrow morning.
There is a 40% to 50% chance for rain on station by Thursday
evening.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions with
generally high based clouds are forecast this evening. Mid layer
cloud decks will filter into southern Utah terminals overnight into
Thursday morning. A 60% to 80% chance for rain/snow and MVFR
conditions exists at BCE after 12z and through the morning while a
50% or great chance for rain exists at SGU and CDC after 18z. VFR
conditions are expected to remain at these terminals. MVFR stratus
decks or LIFR fog banks are possible at ENV, LGU and HCR in
particular tonight.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory from 2 PM Thursday to 5 PM MST Saturday
for UTZ110-111.
Winter Weather Advisory from 8 AM Thursday to 5 PM MST Saturday
for UTZ112-113.
Winter Weather Advisory from 11 AM Thursday to 5 PM MST Saturday
for UTZ117.
Winter Storm Warning from 8 AM Thursday to 5 AM MST Saturday for
UTZ125.
Winter Weather Advisory from 8 AM Thursday to 5 AM MST Saturday
for UTZ126-127.
WY...None.
&&
SHORT TERM...Warthen
LONG TERM...Wessler
AVIATION...NDeSmet
For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecityThe national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
Snow water equivalent at several SNOTEL sites ranged from 1.9-2.8 inches, with an estimated 15-25 inches of snowfall accumulation.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2024Every state in 2024This day in weather historyWarnings in Utah, February 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1162784.