934
FXUS65 KSLC 141030
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
430 AM MDT Fri Jun 14 2024

.SYNOPSIS...Above average temperatures remain in place today with
an upper low bringing low to medium chances for isolated showers
and thunderstorms over eastern Utah. Regional weather gradually
changes through the weekend as a storm system develops over the
West, bringing cooler temperatures late by early next week.

&&

.SHORT TERM (Through 12Z/6AM Sunday)...An area of low pressure
progresses across the region today, bringing increased moisture
and low end chances for showers and thunderstorms over the eastern
half of Utah. Cloud cover and stronger overnight winds associated
with this area of low pressure have spread across much of the
area late yesterday evening, and have contributed to high
overnight low temperatures. As of 0400, temperatures at KSLC
remain at 81 degrees... 8 degrees higher than the daily record
high minimum temperature, and just 1 degree off from the all time
record high minimum temperature. Similar temperatures are being
observed across the Wasatch Front. As such, the existing heat
advisories remain in effect through 6AM. It is unlikely that these
headlines will need to be extended as temperatures gradually cool
over the next few days as trough begins to develop over the West.

Today, temperatures will remain 5-10 degrees above average across
the region today. Increased moisture associated with the
aforementioned low will bring isolated showers and thunderstorms
over the eastern portions of Utah this afternoon, however, there
is very little potential for these showers to produce much
precipitation. However, slow storm motion could allow for stronger
storms to moisten up the sub-cloud environment more rapidly and
allow for brief, but moderate to heavy, rainfall. Because of this,
there still exists a non-negligible threat for flash flooding in
slot canyons, dry washes, and slickrock areas.

Late this evening, an upstream trough will begin its progression
inland and will bring significant changes by early next week.
Leading up to the arrival of the trough and its associated cold
front, there will be increasing concerns for fire weather
conditions (see "Fire Weather" portion of the discussion for more
details). Gradual cooling of overhead temperatures is expected
across at least the northern half of the forecast area up to the
trough`s arrival, resulting in cooler temperatures for Saturday
from about Tooele County northward. For areas south of Tooele
Co., temperatures will see minimal change, if not warming by a few
degrees on Saturday. Breezy afternoon conditions are expected
across much of the region on Saturday, but particularly across the
southern half of Utah. Hot, dry, and breezy conditions will bring
concern for fire weather headlines, however, recent models have
backed off ever so slightly with winds, making Saturday more of a
borderline fire weather day for the zones that currently have
critically dry fuels. As such, have maintained Fire Weather
Watches for fire zones 498 and 497.


.LONG TERM (After 12z/6AM Sunday)...A potent, spring-like cold front
will bring temperatures near 10 to 20 degrees below normal by
Tuesday, a great contrast to the heat we have seen in recent days.

On Sunday, a shortwave trough will be resting just off the coast of
the PacNW. As it begins to push inland, pre-frontal southwesterly
winds will increase on Sunday afternoon, especially across southern
UT. Ensemble mean wind gusts are around 35-45 mph in this area
mainly south of I-70. Monday afternoon wind gusts are likely to be
even higher, reaching 40-50 mph just ahead of the frontal passage.
The 90th percentile wind gusts (a reasonable worst case scenario)
even approach 60 mph in isolated areas.

Just behind the frontal passage, gusty northwesterly winds are
likely, along with a sharp drop in temperatures. The air mass will
remain quite dry even with the front, despite the system`s oceanic
origins, with only a few isolated showers along the UT-ID border
Monday evening. Tuesday high temperatures are likely to be 10 to 20
degrees below normal, translating to the upper-60s along the Wasatch
Front and low-90s in St. George....more akin to highs in early May.

There is, however, still some remaining uncertainties in the
forecast, mainly pertaining to timing of the frontal passage and the
degree of cooling across the area. There are still 20% of members
that favor a less aggressive cooldown, with 700-mb temperatures near
+4C...in contrast to the other 80% that suggest around -2C.

In summary, the biggest impacts with this system will be gusty pre-
frontal southwesterly winds, below-normal temperatures, and areas of
critical fire weather conditions (see Fire Weather section below).
Beyond Tuesday, temperatures will steadily increase once again.

&&

.AVIATION...KSLC...Southerly winds will continue through the
morning, though speeds/gusts will gradually decrease after 12z.
Winds will then transition to northwesterly around 20-21z, returning
to southerly around roughly 03-05z.

.REST OF UTAH AND SOUTHWEST WYOMING...Southerly winds will gradually
decrease through the morning, staying relatively light though
favoring a southwesterly direction through the afternoon. Scattered
showers and isolated thunderstorms are expected across eastern UT
after roughly 18z. Any of these storms will be capable of producing
gusty and erratic outflow winds.

&&

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

     Fire Weather Watch from Saturday morning through Monday evening
     for UTZ498.

     Fire Weather Watch from Sunday morning through Monday evening
     for UTZ497.

WY...None.
&&

$$

SHORT TERM...Webber
LONG TERM...Cunningham
AVIATION...Cunningham

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