110
FXUS65 KSLC 131041
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
441 AM MDT Thu Jun 13 2024

.SYNOPSIS...Anomalous heat persists today, with potential for triple
digit readings along portions of the Wasatch Front for the first
time this year. A mid to upper level low will move through late
today through Friday, bringing a slight cooldown and some low end
precipitation chances. A stronger storm system looks to affect the
area early next week, bringing gusty winds and much cooler
temperatures.

&&

.SHORT TERM (THROUGH 12Z SATURDAY)...The axis of the upper ridge
over the area has shifted east this morning, allowing for increased
southwest flow into Utah. Upstream, a closed low remains in place
off the SoCal and northern Baja coast, but will be advancing inland
later today. Meanwhile, a few lingering showers remain in place
across far northern Utah. These are not producing much in the way of
precipitation or winds at this time, and should taper off shortly
after sunrise as PWATs decrease across northern Utah.

As the low approaches Utah, breezy conditions can be expected today,
especially across southern Utah. Midlevel moisture will also start
to spread into the area from the south. As such, expect increasing
cloud cover across southern/eastern Utah today with some weak, high-
based showers which may produce a few gusty microbursts. This
moisture will lead to a slight drop in temperatures across the south
today. However, across northern through west-central Utah, dry
conditions, better mixing, and slightly higher H7 temperatures near
the Idaho border should result in afternoon max temperatures as high
as, or slightly higher than, yesterday. The latest NBM has a 61%
chance of SLC reaching 100 degrees today.

As the low continues to progress inland, it will fill before
ejecting across the Four Corners area tomorrow. Midlevel moisture
will continue to increase ahead of this storm system. However, the
latest models are increasingly shunting the bulk of the moisture
farther east. As such, the prospect of seeing any appreciable
amounts of precipitation has decreased. Still, expect a few high-
based showers to continue across southeast Utah overnight tonight,
then increase in coverage tomorrow afternoon over the spine of Utah
and into the eastern valleys. Gusty microburst winds remain the main
threat. Cooler temperatures will also spread into the area by
tomorrow, decreasing the threat of significant heat. That said,
afternoon maxes tomorrow remain up to 5 degrees above normal across
southeast Utah, and 6-12 degrees above normal elsewhere.


.LONG TERM (After 12z/6AM Saturday)...Model guidance continues to
trend cooler with the potent cold front arriving on Monday. Expect a
stark transition to spring-like temperatures, contrasting the near-
record heat we have seen this week.

At the start of the long-term, a strong closed low will likely be
positioned over WA and southern BC. As it inches closer over the
weekend, expect a gradual cooling trend on Saturday and Sunday with
highs returning to around normal by Sunday. With a strengthening
pressure gradient as the trough begins to push southward, gusty
southwesterly winds are expected to develop Sunday afternoon. The
highest winds will occur mainly south of I-70, with current ensemble
mean gusts reaching 30-40 mph. Winds are likely to peak Monday
afternoon ahead of the cold front, with ensemble means exceeding 50
mph in portions of southern UT.

As the upper-level trough swings across the northern Great Basin and
into the Intermountain West, its cold front will push through our
area on Monday. The air mass will likely be too dry for much
precipitation, aside from a few isolated showers near the UT-ID
border just behind the frontal passage.

Uncertainties in the upper-level pattern still remain, with
disagreement of the timing of the cold front and extent of cooler
temperatures. Models have overall trended a bit later with the cold
front, now looking more likely for late Monday into Tuesday.
Eighteen percent of ensemble members suggest a much milder cooldown,
with 700-mb temperatures dipping down to +6C. On the other end of
the spectrum, another 21% of members favor a more aggressive
cooldown with 700-mb temperatures reaching -5C. The remainder are
somewhere in the middle, with a mean around -2C, which is still
below the climatological 10th percentile for mid-June. At the
surface, this translates to highs around 70F across the Wasatch
Front and near 90F in far southern UT...though keep in mind that
there is still a 10 degree spread in the NBM 25th-75th percentiles.

&&

.AVIATION...KSLC...Southeasterly winds will continue at least
through the morning, becoming light and variable at times. Heading
into the afternoon, there is high uncertainty with whether or not
the lake breeze (and thus NW winds around 10kts) makes it over the
terminal Thursday afternoon. There is currently a 60% chance that
this occurs, with the most likely timing being after 20z. Otherwise,
there is a 40% chance that southerly winds with gusts to 25kts
persist through the afternoon.

.REST OF UTAH AND SOUTHWEST WYOMING...Gusty southwesterly winds will
develop after 17z, especially across areas south of KDTA-KPUC.
Scattered showers and isolated thunderstorms are possible after 20z
southeast of roughly KBCE-KPUC, likely continuing well into the
evening hours. Gusty and erratic winds are possible near these
showers.

&&

.FIRE WEATHER...High pressure over the area will start to shift
east today, bringing increased southwest flow while maintaining hot
temperatures over the area. Winds will be strongest this afternoon
over southern Utah, which will bring locally critical fire weather
conditions to south-central Utah where fuels have cured. Midlevel
moisture will begin to spread into south-central and southeast Utah
this afternoon, with weak, high-based showers possible. These will
have the potential to bring a few erratic and gusty outflow winds.
Moisture will increase more tonight into tomorrow, bringing an
increased threat of measurable rain, although the wetting rain
chances remain on the low side. Gusty outflow winds will continue to
be the main threat. Otherwise, will see temperatures to cool a bit
into the weekend.

A relatively deep trough for this time of year is anticipated to
carve into the area for the first half of next week. Ahead of this,
gusty southwest winds Sunday into Monday could bring another round
of critical fire weather conditions to areas where fuels have cured.
Much cooler temperatures can then be expected as this storm tracks
into the area, although it is not expected to be accompanied by much
in the way of moisture.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Heat Advisory until 6 AM MDT Friday for UTZ101-102-104>106.

     Red Flag Warning from noon today to 9 PM MDT this evening for
     UTZ498.

     Excessive Heat Warning until 10 PM MDT this evening for UTZ131.

WY...None.
&&

$$

Cheng/Cunningham

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