NWS Salt Lake City, UT wrote its last area forecast discussion before the first event at May 4, 3:04 PM MST, 4 hours 21 minutes earlier.
Area forecast discussion, May 4, 3:04 PM MST, 4 hours 21 minutes before
Area Forecast Discussion
National Weather Service Salt Lake City UT
404 PM MDT Sat May 4 2024
.SYNOPSIS...Southerly winds will continue to increase ahead of a
storm arriving on Sunday. This storm will bring a cold front that
will be precluded with strong wind gusts, particularly across
western and southeastern Utah, on Sunday. Widespread valley rain
and mountain snow will accompany the cold front with much colder
temperatures. Conditions remain unsettled and cold through
midweek.
&&
.SHORT TERM (Through 12Z/6AM Monday)...The low pressure system
that will bring our weather back to winter-like conditions is
currently situated just off of the west coast between OR and CA.
This low will quickly move inland, with a potent cold front
producing a stark transition to cooler temperatures, plentiful
mountain snow, and weaker northwesterly winds on Sunday.
As the low continues to shift inland, southerly winds will
continue to increase. Winds have been picking up this afternoon,
with peak gusts into the 40s (mph) across the West Desert and
into the 30s across portions of the Wasatch Front. Across these
areas, winds will peak overnight, up to 60 mph in western
Millard/Juab counties. This core of stronger winds will then shift
eastward, with winds peaking across eastern valleys Sunday
afternoon. A potential limitation in winds here is increasing
cloud cover that would limit full mixing of H7 winds around 50kts
down to the surface. Temperatures will also peak today, with
current temperatures in the upper-70s along the Wasatch Front and
mid-80s in lower Washington county.
The arrival of the cold front will greatly contrast today's
weather. Abundant moisture combined with great mid-level and jet
dynamics will produce widespread precipitation in the form of
valley rain and mountain snow. The highest precipitation totals
are expected across northern areas given more moisture
availability and better dynamics. Snow levels, while initially
quite high around 9000ft, will plummet behind the cold front down
to around 5000ft by late Sunday night. Given antecedent warmth,
snow may struggle to stick across lower elevations (roughly below
7000-8000ft), despite heavy snowfall rates along the front
nearing 3 inches per hour. Thunder is also possible along this
baroclinic zone, especially across higher terrain. This front will
likely reach northwestern Utah early Sunday morning, also reaching
the Wasatch Front by noon and southeastern Utah by Sunday evening.
Behind the front, winds will transition to west-northwesterly,
thus terrain favored in this flow regime will do especially well
snow-wise through Sunday night given a persistent moist, unstable
environment.
Regarding QPF and snow totals (through Tuesday), many northern
Utah valleys may see upwards of 0.8-1.4" of rain, with most
central and southern valleys seeing quite a bit less, less than
0.25". The northern mountains can broadly expect 1-2" of liquid
equivalent or 8-16" of snow with locally higher amounts in west-
northwesterly favored areas such as the Upper Cottonwoods or
Ogden-area mountains. Amounts could be even higher in the case of
lake-enhancement...which is looking most likely along the
northern Wasatch.
.LONG TERM (After 12Z/6AM Monday)...Our forecast through next week
is largely unchanged for the first half of week where northwest flow
persists behind an area of low pressure. The latter half of the week
and into the weekend however, our forecast begins to become
uncertain regarding the track of this same low. Deterministic models
are continuing to show an area of high pressure pushing that low
back toward our region and settling somewhere to the west. It's an
interesting/odd progression for a low. When that progression occurs,
how fast it happens and exactly how it'll impact Utah still is to be
seen. Those with any plans over the weekend statewide that may be
impacted by rain should certainly continue to keep updated on the
latest forecast trends.
But back to the first half of the work week's forecast. Mountain
snow showers, valley rain, thunderstorms and possible lake effect
snow bands remain in the forecast across northern Utah (Nephi to the
Idaho border) and southwest Wyoming for Monday, Tuesday and
Wednesday. A winter storm warning is currently forecast through
Tuesday for the northern Utah mountains and western Uinta Mountain
ranges.
Snow on area benches in the Wasatch Front (and possibly
in the Tooele Valley) continues to look pretty favorable Monday
morning. In fact, snow may (20% chance) reach valley floors for some
in the southern Salt Lake Valley and Utah County areas with snow
levels forecast down to 4700 ft. At least though, any impacts from
this would be short lived and minimal, as temperatures climb well
above the freezing mark Monday.
Now speaking of temperatures, while they are above freezing we are
well below normal for May 6th, 7th and 8th. Our temperature forecast
across northern Utah remains forecast 15 to 20 degrees below
normals. Monday and Tuesday's temperature forecast will be very
similar while the coldest morning is forecast for Wednesday. Morning
lows are expected below or at the freezing mark for several
locations in the valleys (and well below freezing in the Wasatch
Back and in the mountains). Headlines for a freeze warning for some
valleys remain very possible if these trends persist.
Westerly winds Monday afternoon into the evening across the western
Uinta Basin and for southwest Wyoming continue to look strong with
speeds in excess of 30 mph and gusts exceeding 50 mph. As a result,
a wind advisory will be issued for the western Uinta Basin while
headlines are not being issued as high wind criteria is not quite
met for southwest Wyoming.
Tuesday afternoon is looking like a favorable time frame for
thunderstorm activity as a decent shortwave trough passes through
northern Utah. Favorable amounts of instability and shear should be
enough for at least a few thunderstorms to develop but what might be
missing from the equation is enough moisture.
South of the Nephi area, modest weather conditions are forecast the
first half of the week. The best chances for any precipitation is
forecast for Tuesday and only for central Utah locations.
&&
.AVIATION...KSLC...Active period as a cool to cold season type storm
approaches and moves through. With increasingly strong low level
south flow, will see surface winds/gusts increase accordingly. Gusts
likely maintained overnight into early Sunday, but could see some
periods of low level wind shear if surface decouples and gusts drop.
Precipitation chances increase prior to sunrise, which should help
carry strong gusts downward. By late morning, shower chances become
increasingly likely ahead of cold front, though strong south flow
may initially yield some downsloping off terrain, abating precip to
an extent. Front passes early afternoon, with winds switching to
northwest and gradually relaxing. Widespread precip continues with
MVFR conditions fairly likely during times of heavier precip.
.REST OF UTAH AND SOUTHWEST WYOMING...An anomalous cool to cold
season system will approach and move through the region, resulting
in active TAF period. As the storm approaches Saturday into early
Sunday, most terminals will see increasing southerly winds and
gusts, with gusts 30-45 kts possible at many terminals. If any
terminals (generally those more sheltered) can decouple overnight,
expect gusts to subside a bit, but in turn would see low level wind
shear develop. As precipitation chances increase prior to sunrise,
will see higher confidence in gusts being maintained. Precipitation
chances become further elevated through the morning and afternoon as
cold frontal boundary moves through. MVFR conditions likely in
heavier precip, with IFR possible at higher elevation terminals
where snow may mix in. Strongest winds/gusts will begin to subside
following the frontal passage, with directions largely trending more
west to northwesterly.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory until noon MDT Sunday for UTZ101-102-122.
Winter Storm Warning from 6 AM Sunday to noon MDT Tuesday for
UTZ110>112.
Wind Advisory from 6 AM to 10 PM MDT Sunday for UTZ114-120-121-
126>131.
High Wind Warning until noon MDT Sunday for UTZ115.
WY...None.
&&
Cunningham/NDeSmet/Warthen
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