532
FXUS65 KSLC 292114
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
314 PM MDT Sat Jun 29 2024

.SYNOPSIS...High pressure will bring hot and dry conditions
through the remainder of the weekend. Increasing southwest winds
will bring the potential for critical fire weather conditions into
Monday across western Utah. A cold front will cross the region
early next week bringing a cooldown for the midweek period.

&&

.SHORT TERM (Through 12Z/6AM Monday)...Southwesterly flow resides
across the Great Basin region this afternoon, sandwiched between
an upper trough along the Pacific Coast, and an elongated
subtropical ridge axis extending into the Desert Southwest.
Lingering moisture remains across eastern Utah, and has supported
isolated convection from the Manti-Skyline area northward into
the western Uintas. This convection should quickly diminish with
the loss of daytime heating. Further south, an additional plume of
moisture noted across central/southern Arizona eastward into New
Mexico. Meanwhile, much drier air resides across western Utah
where afternoon RH values are running in the single digits, and
temperatures in the mid to upper 90s including KSLC.

This hot and dry airmass will remain across western Utah through
Sunday, allowing KSLC to make a run at the 100F mark. The
moisture plume across the Desert Southwest will spread into
eastern Utah, bringing an increase in convective coverage as
compared to today, and have increased PoPs across these areas. By
Sunday evening a dry frontal boundary will push into far northwest
Utah, crossing the Wasatch Front during the evening hours.

.LONG TERM (After 12Z/6AM Monday), issued 314 AM Saturday...A bit
of a cooldown is our weather headline for the first of July,
which is not the headline you would anticipate. This cooldown
won`t impact all of our area, but the northern 2/3rds of Utah will
feel the impacts. The set up here is a fairly broad and far
reaching trough of low pressure across the western US, tracking
very slowly eastward through mid- week. There isn`t a forecast
model that doesn`t support this solution so there is quite good
confidence in these cooler conditions.

The trough moves so slow in fact that conditions Monday compared to
Tuesday are quite similar, or even cooler. Conditions are mainly
expected to be dry across the region, in all areas except far
southeastern Utah where some moisture may reside. A slight risk for
showers and thunderstorms will exist in areas like Lake Powell/Glen
Canyon where lift is supportive ahead of the trough.

If forecast confidence wavers any, it will be in the mid-week time
frame when the low exits and strong high pressure begins to build in
from the west. The transition period timing does differ between
forecast models with the GFS bringing in the high by Wednesday while
the ECMWF waits until later in the week.

Friday and into the weekend, temperatures become a tough forecast.
Consensus is for high pressure to be parked somewhere over the
western US. However, it will make a difference which areas feels the
heat the most based on where it does situate itself. Essentially,
there`s a 50/50 split amongst ensemble models favoring hotter
temperatures or favoring cooler temperatures in our area. The
hotter temperatures would arrive under high pressure centered
directly over our area, favored mostly by the GFS, whereas favored
cooler temperatures are noted by northwest flow associated with
an area of low pressure to our north. The range for possible
temperatures outcomes widens Friday and Saturday, which is no
surprise looking at this uncertainty.

&&

.AVIATION...KSLC...No precipitation and clear to mostly clear
skies expected at the terminal. Enhanced southerly drainage flow
anticipated overnight into Sunday morning with a few gusts
possible. Gusts pick up and southerly winds are then maintained
through the day Sunday.

.REST OF UTAH AND SOUTHWEST WYOMING...Isolated diurnal convection
possible across eastern Utah through Saturday evening, with some
redevelopment possible Sunday afternoon. Otherwise, anticipate
mostly clear to partly cloudy skies and VFR conditions. After
following a somewhat typical diurnal pattern overnight, enhanced
south to southwesterly winds and gusts expected through the day
Sunday.

&&

.FIRE WEATHER...A hot southwesterly flow will reside across the
region through the remainder of the weekend. Across western Utah,
the airmass will remain very dry, with daytime RH values in the 5
to 10% range. This combined with gusty afternoon winds will result
in critical fire weather conditions across west central and
southwest Utah Sunday, and have upgraded to a Red Flag Warning
across these areas. Further east, the next surge of monsoon
moisture across Arizona will spread across the eastern half of
Utah Sunday afternoon, resulting in elevated daytime RH along with
isolated to scattered showers and thunderstorms. Given the
elevated RH values, have dropped the Fire Weather Watch for Sunday
across zone 498.

A cold front will push into northern Utah late Sunday, then slowly
cross central and southern Utah late Monday through Monday night.
Ahead of this front, hot dry and breezy conditions will persist
across central and southern Utah, where the Red Flag Warning will
remain in effect through Monday evening. RH is a bit more marginal
across the eastern half of the state Monday, thus have held onto
the Fire Weather Watch for zone 498 for now.

A cooler but dry airmass will follow the front for Tuesday, along
with daytime northwest winds. A gradual warming trend will follow
for the remainder of the week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Red Flag Warning from noon Sunday to 9 PM MDT Monday for UTZ492-
     495>497.

     Fire Weather Watch from Monday afternoon through Monday evening
     for UTZ498.

WY...None.
&&

$$

Seaman/Warthen/NDeSmet

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