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Office: SLC

FXUS65 KSLC 102149
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
349 PM MDT Wed Aug 10 2022

.SYNOPSIS...Abundant moisture will continue to spread across the
Utah and southwest Wyoming and remain in place through the
weekend, ensuring daily shower and thunderstorm chances.

&&

.SHORT TERM (through 12Z Friday)...Abundant moisture is noted
across western Utah, Idaho and Nevada today. PW values across
western Utah are approximately 200% of normal. EC ensembles
continue to indicate anywhere from 1.0 to 1.4 inches of available
water today, which will spread a bit more northeastward tomorrow,
extending further across the state. A slight risk for excessive
rainfall from WPC continues over the western half of the state for
today. A Flood Watch will continue through midnight in much of
these same slight risk identified areas and is in effect for excessive
rainfall and flash flood potential. Favored areas of instability
for the remainder of the evening is noted over western Utah across
Box Elder and Tooele counties where effective bulk shear values
of 30 to 40 kts and CAPE of 1000-2000 J/kg are forecast. As a
result, these areas may see the most developed thunderstorms
with gusty winds and frequent lightning as the primary threats.

A slight risk for excessive rainfall from WPC is noted tomorrow
in a broad area across much of the state. Scattered to numerous rain
showers with risk for thunderstorms are once again forecast during
the afternoon into the evening hours. Heavy rain impacts tomorrow
extend into portions of the Uinta Mountains and into the Wasatch
Mountains, which is not necessarily forecast for this evening.
Scattered to numerous rain showers with risk for thunderstorms
are forecast from the Arizona border to the Idaho border. Areas in
eastern Utah will have the best chance for remaining dry but a chance for a
thunderstorm is still possible in these areas. Considering the
available moisture and expected heavy rain impacts, a new Flood
Watch has been issued for Thursday afternoon into Thursday evening
for many of the same areas as today with a slight extension
northward.

.LONG TERM (after 12Z Friday)...High confidence remains in the
extended forecast period remaining active for a majority of the
area as monsoonal moisture keeps rain showers and thunderstorms
likely for every afternoon and evening. This will keep the
likelihood of flash flooding for many popular slot canyons,
National Parks and burn scars across the state of Utah,
particularly in southern Utah. Ongoing precipitation across Utah
and SW Wyoming is expected to keep more mild temperatures through
the extended as well with consistent cloud cover.

Both ensemble and deterministic models remain in agreement on a
ridging pattern sitting just east of the 4 corners region that will
keep south/southwesterly flow over western UT which will feed
sufficient moisture for storm development over the extended. PWAT
values still remain around 1-1.5" through the extended for much of
the state with peak values being near the St. George area.

Models also are coming into more agreement of a NW Pacific low
pressure system to move north and east over the extended which will
allow for the ridging pattern to extend further westward and
continue the monsoonal push through midweek and possibly further.
There is growing guidance that as the ridge builds westward we could
see a slight shift to more zonal flow aloft which will push moisture
and storm development closer to the UT/CO border rather than
statewide.

&&

.AVIATION...KSLC...VFR conditions expected for KSLC. Northerly
winds expected to switch to southerly between 05Z and 07Z and then
switch to northerly between 17Z and 19Z tomorrow. Scattered
showers and thunderstorms are possible between 00Z and 04Z. When
under or near these storms, gusty and erratic outflow winds are
possible. Precipitation chances decrease after 04Z and then
increase late tomorrow afternoon along with increasing mid- level
cloud cover.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions expected for
all terminals. Winds are expected to be diurnal for the period.
Scattered showers and thunderstorms will continue for most of the
CWA. Under these storms, conditions could go to MVFR and winds
could become gusty and erratic. Storms will subside by ~08Z.
Scattered showers and thunderstorms pick back up for most of the
area tomorrow early afternoon.


&&

.FIRE WEATHER...Abundant moisture is noted across much of the
state and particularly over western Utah this afternoon. Scattered
to numerous thunderstorms are forecast during the afternoon and
evening hours. Heavy rain, frequent lightning and gusty winds are
likely to accompany thunderstorms. Wetting rains of 50 percent and
higher are forecast across much of western and southern Utah,
extending into the mountain of central and northern Utah tomorrow.
Eastern Utah locations are much drier, though a chance for a
thunderstorm is still possible both this evening and again
tomorrow afternoon and evening in these locations.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch until midnight MDT tonight for UTZ115>119-122>127.

     Flood Watch from Thursday afternoon through Thursday evening for
     UTZ102-115>119-122>127.

WY...None.
&&

$$

SHORT TERM...NDeSmet
LONG TERM...Selbig
AVIATION...Cecava
FIRE WEATHER...NDeSmet

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visit...
http://weather.gov/saltlakecity/general/afd_faqs.php