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059
FXUS65 KSLC 172156
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
356 PM MDT Mon Jun 17 2024

.SYNOPSIS...
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A strong cold front will continue to cross the region
through this evening, bringing a much colder airmass to the area
for Tuesday. Temperatures will quickly moderate midweek, with
another period of very hot temperatures by Sunday.
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&&

.SHORT TERM (THROUGH 12Z WEDNESDAY)...
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An upper trough continues to
track across Idaho and northern Nevada into northern Utah this
afternoon. A powerful by mostly dry June cold front associated
with this trough is currently making its way through the forecast
area. Latest surface analysis shows the surface boundary
extending from west-central Utah into the western Uinta Basin.
Meanwhile, the H7 baroclinic zone lags the surface front a bit,
but has already made it to SLC. Strong gusty winds are noted on
both sides of the boundary, with a few postfrontal wind gusts in
excess of 58 mph so far across the northwest deserts. Expect
strong postfrontal winds to continue as the front continues to
make its way into southern Utah this evening, and could be
especially strong in favored downslope areas. Wind highlights are
in effect for some of these areas. However, have left out other
favored areas such as northern Utah County and the Uinta Basin, as
these are currently not quite expected to see the duration needed
for an advisory. Something worth keeping an eye on nonetheless.

Much colder temperatures will spread into the area behind the cold
front. Overnight mins tonight will be around 15 degrees below normal
across northern Utah, and around 5-10 degrees below normal across
much of southern Utah. Some valley areas, especially mountain
valleys, will see mins near to below freezing. The Freeze Watch
for the Wasatch Back has been upgraded to a Freeze Warning. For
tomorrow, afternoon maxes will remain on the cool side at around
14-20 degrees below normal across the north and 5-12 degrees below
normal across the south as a mean trough settles over the area.
Otherwise, winds will be weaker tomorrow with relatively benign
weather other than the cold.


.LONG TERM (After 12z/6AM Wednesday), Issued 426 AM MDT...
Following the much anticipated early week trough, model guidance
maintains good agreement on mean troughing remaining in place to
the west of the forecast area through much of the upcoming week.
An upstream trough will promote increasingly warm southwesterly
flow which will strongly favor temperatures warming from right
around climatological normals on Wednesday to well above normal by
Sunday. In fact, by Sunday the Salt Lake City area could see
another shot at 100 degrees as model statistics support a 50
percent chance of exceeding 99 degrees and a nearly 40 percent
chance of exceeding 100 degrees! For the St. George area,
temperatures could easily rise back into the mid-100s. For both of
these areas during the overnight period lows may only drop into
the mid-to-upper 70s, providing very little recovery for those
without proper cooling. There is generally medium to high
confidence in this warm up through the second half of the week. As
such, will need to evaluate heat risk for these areas over the
coming days as headlines may need to be considered.

Another aspect of the forecast that will be a welcomed change is the
increasing confidence in the introduction of moisture over the
eastern half of Utah late in the work week. Leading up to about
Friday, dry and breezy southwesterly flow will keep much of Utah
with elevated, to near-critical, fire weather conditions. However,
models showing increasing potential for moisture to ooze in from the
Gulf of Mexico and spread across the eastern half of Utah. Most of
the moisture increases are noted in the lower-to-mid levels which
will help to destabilize the atmosphere and bring potential for
stronger thunderstorms over the eastern half of Utah. GEFS and EPS
both show precipitable water levels upwards of 190 to 250 percent of
normal by Friday, respectively. This potential moisture flux could
very well give us one of our first hydrologically concerning events
for slot canyons, slickrock areas, and burn scars. After Friday,
moisture wanes and we return to mostly dry conditions across the
area... though isolated showers and thunderstorms are likely to
linger across the eastern half of Utah through at least Saturday.
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&&

.AVIATION...
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KSLC...Gusty post-frontal NW winds gradually subside
from late evening into the overnight hours, with any lingering
precipitation and denser cloud cover also gradually clearing. By
around 10Z or so, lighter N winds become more VRB, with VRB to light
S drainage flow then expected through mid to late morning Tuesday.
NW flow then becomes reestablished by late morning and is maintained
thereafter, with skies remaining mostly clear to clear.

.REST OF UTAH AND SOUTHWEST WYOMING...Cold front to continue
southward through the area. Northern terminals likely start in a
gusty post-frontal environment, with some low chances (less than
20%) of lingering precipitation. Conditions gradually improve moving
into the overnight hours, with winds trending downward and remaining
precip and VFR cloud cover mostly clearing. At southern terminals,
front will begin pushing through late Mon evening. Precipitation is
not expected, but an abrupt shift to gusty N winds is anticipated,
with gusts then lingering on into the overnight for several hours.
Gusts will begin to subside moving closer to sunrise, with some
exception potentially at SGU where threat for a bit prolonged
downslope/gap winds are noted (though low confidence in exact
magnitude and duration at the terminal). Moving into the day
Tuesday, more benign weather conditions expected to set in.
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&&

.FIRE WEATHER...
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A very strong but dry cold front will continue to
push south through Utah through this evening. Strong Gusty winds
are expected both ahead of and behind the front. The winds will
combine with low humidities to continue to create critical fire
weather conditions through this evening across southern Utah
where fuels have cured. Isolated weak, high-based showers remain
possible through this evening across northern Utah behind the
front, producing very little to no rainfall but may briefly
enhance the already strong winds. Much cooler temperatures will
spread into the area behind the front for tonight and tomorrow.
Humidity recoveries should also improve across all but the lower
valleys of far southern Utah.

Temperatures will trend warmer again Wednesday into late week,
with afternoon relative humidities remaining on the low side.
Increasing winds on Thursday could potentially bring another round
of critical fire weather conditions to areas where fuels have
cured. Models are coming into good agreement on moisture spreading
into the eastern portions of the area Thursday into Friday, with a
chance of some areas seeing wet thunderstorms by Friday.
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&&

.SLC WATCHES/WARNINGS/ADVISORIES...
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UT...High Wind Warning until 9 PM MDT this evening for UTZ101.

     Freeze Warning from 9 PM this evening to 9 AM MDT Tuesday for
     UTZ108.

     Wind Advisory until 3 AM MDT Tuesday for UTZ120.

     Red Flag Warning until 9 PM MDT this evening for UTZ495-496.

     Red Flag Warning until 3 AM MDT Tuesday for UTZ498.

     Wind Advisory from 9 PM this evening to 8 AM MDT Tuesday for
     UTZ123.

     Red Flag Warning until midnight MDT tonight for UTZ497.

WY...None.
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&&

$$

Cheng/Webber/Warthen

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