NWS Salt Lake City, UT wrote its last area forecast discussion before the first event at May 12, 8:57 AM MST, 1 hour 33 minutes earlier.
Area forecast discussion, May 12, 8:57 AM MST, 1 hour 33 minutes before
Area Forecast Discussion
National Weather Service Salt Lake City UT
957 AM MDT Mon May 12 2025
.UPDATE...Given current wind observations, winds are already
overperforming in many western Utah valley locations, and high res
ensembles support a broader threat area for wind gusts in excess
of 40 mph. Because of this, have expanded the going Wind Advisory
to include the majority of western Utah valleys, including the
Wasatch Front. No other changes anticipated. Previous discussion
follows.
&&
.SYNOPSIS...Very mild conditions persist into early next week, with
increasingly gusty winds as a deep system approaches. A strong
cold front associated with this system will pass through the
region late Monday evening into early Wednesday, ushering in a
period of cooler and more unsettled weather.
&&
.SHORT TERM (through 00z Thursday/6 PM Wednesday)...This
morning's GOES satellite mid-level water vapor imagery shows an
area of low pressure spinning off the coast of northern
California, with Utah and southwest Wyoming wedged between this
feature and a stout ridge east of the Rockies. This pattern has
maintained elevated southwesterly flow across the region overnight
into this morning. In fact, surface winds remain quite strong
across the region this morning, with gusts still in the 20-30 mph
range across portions of Utah and southwest Wyoming. These
conditions have allowed for continued mixing within the boundary
layer overnight, when in conjunction with H7 temperatures +9C have
resulted in low temperatures around 15-20 degrees above
climatological normals this morning. This morning's low
temperatures were nudged upwards in the latest forecast package to
account for this.
As the aforementioned low deepens along the west coast today,
southwesterly flow will further strengthen through this afternoon as
the pressure gradient tightens across the region. Wind gusts across
the forecast area will tick up significantly late this morning, with
widespread wind gusts to 30-40 mph into this afternoon and evening.
Stronger gusts are favored across the West Desert and Tooele and
Rush Valleys today, with gusts upwards of 55 mph likely; a Wind
Advisory was hoisted for these areas as a result. Given recent dry
conditions, strong winds today will be capable of producing patchy
blowing dust downstream of desert sinks or other sources of dust,
especially across western Utah.
The trough is expected to track into the Great Basin late today,
with an associated cold front nudging into northwestern Utah by the
evening hours. This front is expected to gradually sweep southeast
overnight into Tuesday morning. Winds switch northwesterly and ease
behind the front. Strong cold air advection behind the front will
yield temperatures around 20 degrees cooler on Tuesday, translating
to highs around 5-10 degrees below seasonal normals.
Moisture transport with this system is quite meager, though high-
resolution models support a band of light precipitation accompanying
the frontal passage Tuesday morning. This band is expected to become
quite disorganized by Tuesday afternoon as it reaches central Utah,
with more showery conditions developing in its place. The front will
continue to track into southern Utah into early Wednesday, with more
widely scattered showers developing Wednesday afternoon across the
region.
.LONG TERM (After 00Z Thursday)...Long term forecast period starts
with the axis of a broad mid/upper level trough starting to
translate further into the Intermountain West. Locally, flow will be
or will be transitioning into a deeper northwesterly flow on the
back end of the departing trough. Lingering moisture in combination
with modest PVA will result in a bit of continued northern shower
activity through the overnight hours, with a secondary uptick late
morning on through the afternoon hours generally along/east of the
northern high terrain. While warmer than that of Wednesday,
afternoon high temps Thursday will remain near to a bit below
climatological normal for mid May.
A little bit of uncertainty is noted for Friday. General model
consensus shows some sort of additional weak embedded impulse
translating through overhead, but differences in available moisture
and overall degree of forcing for synoptic scale ascent. Right now
about 40% of models eek out just enough of both for some low end
precipitation chances across the north (largely GFS weighted), with
the remainder favoring drier conditions. Even if things trend
towards a slightly wetter scenario, impacts look quite minimal.
Models have continued to trend towards another system impacting the
area over the weekend, though differences in the pattern evolution
are noted. In general, there is fair agreement that a shortwave will
dig southward through the PacNW and towards the Great basin region
Saturday. Thereafter into Sunday, discrepancies arise. Around 35% of
ensemble members carry this feature either cutting off or moving
through as a deeper trough. The remaining 65% maintain more of an
shallower open wave to grazer type of system. If the deeper trough
to cutoff scenario wins out, anticipate a cooler/wetter/more
unsettled pattern over the majority of the forecast region. In the
more open wave to grazer system, would expect a more muted cooldown
with precipitation potential more favored across northern locations.
There is also a number of timing differences member to member, with
associated potential frontal passage timings ranging anywhere from
Saturday night to Sunday night. Depending on the timing/strength, a
number of models do indicate potential for some localized modest
late-season snow accumulation above 9000 ft or so. Overall though
given all the moving pieces and being about a week out, will have to
monitor trends.
&&
.AVIATION...KSLC...Enhanced southerly winds continue this
morning, further increasing around roughly 17z. A cold front
tracks through the region late this evening, with winds switching
northwest around 06z Tuesday behind the front. Winds are expected
to gradually become lighter thereafter. Scattered rain showers
behind the front may impact the terminal between 18-00z, resulting
in increased low-to- mid level cloud cover during this period.
.REST OF UTAH AND SOUTHWEST WYOMING...Strong south to southwest
winds are expected again today, with gusts ranging from around 25-40
knots much of the TAF period after 16-17z. A cold front tracks into
northern Utah and southwest Wyoming this evening and overnight, with
winds switching northwesterly behind the frontal passage. Increasing
mid-to-low level cloud cover is expected Tuesday afternoon and
evening across the airspace, with scattered showers possible for
northern terminals between 18-00z.
&&
.FIRE WEATHER...Strong, southwesterly pre-frontal winds are
expected across much of Utah on Monday, with strongest gusts
upwards of 50-55 mph expected across the western portion of the
state. Extremely dry conditions will also precede the frontal
passage on Monday, with relative humidities in the single digits
to low teens for most locations. Improvement in overnight humidity
recoveries is expected behind the frontal passage overnight Monday
into Tuesday morning across northern and western Utah, with poor
recoveries across the eastern and southern portions of the state.
Gusty southwesterly winds continue across southeastern Utah on
Tuesday ahead of the cold front passage late Tuesday afternoon. A
cooler, more unsettled pattern will build into the region behind
the front Wednesday into Thursday.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory until midnight MDT tonight for UTZ101>107-115-116-
122.
WY...None.
&&
Traphagan/Whitlam/Warthen
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