Heavy Snow in Utah, February 6 to 9, 2024

Area Forecast Discussion
National Weather Service Salt Lake City UT
405 PM MST Mon Feb 5 2024

.SYNOPSIS...A high elevation winter storm will continue through
Thursday. The active pattern will continue through at least the
first half of the weekend.

&&

.SHORT TERM (Through 12Z Thursday)...A long duration winter storm
will continue to impact the Beehive State through the short term
forecast period. There have been some subtle changes to the
forecast over the last 24 hours.

First up, upper air and satellite analysis indicates a broad area
of ascent associated with the combination of an upper level trough
and a robust southern jet. Heavy rain continues to impact southern
California. This band of enhanced IVT values combined with modest
lift remains stretched across Utah from roughly northwest of Cedar
City to Evanston. The heaviest precipitation with this band is
from roughly Juab County north into the northern Wasatch Front.
Snow rates are averaging around 0.50 to 0.75" or so an hour across
portions of the Wasatch Mountains.

This band will gradually shift north and west and weaken through
midnight to 3 AM or so. This will begin a break in the
precipitation for most of the state.

As the upper level trough begins to shift eastward into the West,
upper level diffluence will combine with a moist, unstable upslope
regime across the southern Utah mountains Tuesday morning into
Tuesday afternoon. Expect precipitation to begin late Tuesday
morning and become heavy at times through the day Wednesday,
potentially into Thursday morning. The southern mountains will be
the most impacted part of the state and thus the winter storm
watch has been upgraded to a winter storm warning with this
package.

Further north, the details become somewhat murkier remove from
both the best synoptic level forcing as well as the best
orographic influence. Much of the guidance supports a period of
lee cyclogenesis across eastern Nevada Tuesday evening, with this
low shifting into far northwestern Utah Wednesday morning. This
may be the best period for moderate to heavy mountain snow across
portions of the northern and central Utah mountains.

Another round of mountain snow, particularly for the northern
mountains is possible as a shortwave trough embedded in the
relatively chaotic flow within the longwave trough shifts across
Nevada into Utah Wednesday evening into Thursday. This period of
potential increased lift is coincident with a period of westerly
to west-northwesterly flow, which may add an orographic component
to snow accumulations. Given lower confidence in warning amounts
and later onset (mainly Tuesday evening and later), held on to the
winter storm watches for the northern and central mountains.

With rain below 7500 feet in orographic enhanced areas of the
lower deserts of southwestern Utah, many rivers, creeks and
streams will be running higher than normal. No mainstem river
flooding is expected, but flows will be higher and very cold
through at least Thursday.

A wind advisory will continue through 5 PM for the Tooele Valley,
where locally strong winds have continued into the afternoon.

.LONG TERM (After 12Z Thursday)...An unstable weather pattern
will remain in the forecast later this week. Rain/snow and colder
air remains on the way with an upper low forecast to dig
southward. The depth of this low still varies between forecast
ensembles but the track has come into good agreement with a
progression through the Intermountain West into the Desert
Southwest headed into the weekend. Widespread snow can be expected
across Utah and southwest Wyoming Thursday and Friday however a
few areas are expected to remain as rain, including lower
Washington County and Lake Powell/Glen Canyon.

While snow is expected to fall across the valleys, mountain
snowfall is expected to be the primary impact Thursday and Friday.
Snow in the valleys is not expected to be continuous nor
particularly heavy. But any heavier showers that may occasionally
occur will not impact the same valleys at the same time. With that
stated, snowfall amounts are on the lower side in the valleys,
ranging from a broad 1 to 3 inches. Some areas where snowfall
uncertainty occurs in the valleys include Cedar City and
Kanarraville. Total snow amounts Thursday and Friday in these
areas are currently between 3 to 5 inches but there's a 10 to 20%
risk for 10 inches. Another area of forecast uncertainty lies in
Kanab and across the Grand Staircase/Escalante areas. Forecast
snow totals are currently indicating anywhere from 1 to 3 inches
with a similar 10 to 20% risk for over 10 inches.

Mountain snowfall, on the other hand, indicate higher totals into
warning criteria thresholds for many mountain ranges. The Tushar
Mountains in particular are indicating 2 feet of new snow in this
48 hour period.

Later Saturday into Sunday, a high pressure ridge building in
from the west is favored, drying out conditions. These drier
conditions are anticipated into Monday.

&&

.AVIATION...KSLC...VFR conditions are expected to remain throughout
the period for the KSLC terminal. Gusty southerly winds will
gradually weaken through the evening with on and off light rain
showers through 05Z. CIGs near ridgetops will create mountain
obscuration. Overnight, southerly winds remain with drier conditions
expected along with CIGs rising above ridge tops.

.REST OF UTAH AND SOUTHWEST WYOMING...Low elevation rain and high
elevation snow will continue until ~06Z for northern Utah and
southwest Wyoming creating reduced flight categories near MVFR for
valley rain and IFR for high elevation snow. Winds will remain gusty
out of the south before weakening overnight. Mountain obscuration
will persist for most locations before CIGs gradually rise overnight
along with drying conditions. Southern Utah will remain mostly VFR
throughout the period with the exception of KBCE where low CIGs will
create intermittent MVFR conditions through the evening.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory until 5 PM MST this afternoon for UTZ102.

     Winter Weather Advisory until 5 AM MST Tuesday for UTZ110.

     Winter Storm Watch from Tuesday afternoon through late Wednesday
     night for UTZ110>113-117.

     Winter Storm Warning from 11 AM Tuesday to 5 AM MST Thursday for
     UTZ125.

WY...None.
&&

Kruse/NDeSmet/Mahan

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