Areal Flood Warning 5, NWS Salt Lake City, UT

096 
WGUS85 KSLC 021351
FLSSLC

Flood Statement
National Weather Service Salt Lake City UT
751 AM MDT Thu Sep 2 2021

UTC017-055-021401-
/O.EXP.KSLC.FA.W.0005.000000T0000Z-210902T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Garfield UT-Wayne UT-
751 AM MDT Thu Sep 2 2021

...FLOOD WARNING WILL EXPIRE AT 8 AM MDT THIS MORNING FOR 
NORTHEASTERN GARFIELD AND SOUTH CENTRAL WAYNE COUNTIES...

Flood waters have receded. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3842 11068 3842 11065 3836 11056 3831 11049
      3815 11039 3815 11038 3805 11036 3789 11036
      3789 11038 3789 11040 3806 11042 3812 11043
      3822 11050 3838 11065

$$

MS

Area Forecast Discussion
National Weather Service Salt Lake City UT
336 AM MDT Thu Sep 2 2021

.SYNOPSIS...A disturbance across the Pacific Northwest will bring
another round of showers and thunderstorms to portions of Utah
today. In the wake of this system Friday through Labor Day weekend,
drier air will build into the state.

&&

.SHORT TERM (Through 12Z Sunday)...Today could be a somewhat
sneaky day for stronger convection across the north and heavy
rainfall potential across the south/east. An upper level trough is
currently located across the Pacific Northwest into the Canadian
Prairie Provinces. Southwesterly flow remains in place across much
of the region. Morning observational analysis shows surface
dewpoints are still almost tropical for Utah, with locations like
Hanksville, Kanab and St. George near or above 60F.

A weak wave is noted cross northwestern Utah this morning.
Sufficient lift is present with this feature for an area of
showers and occasional thunderstorms crossing the Great Salt Lake
Desert at the moment.

The upper level trough is expected to gradually shift eastward
through Friday. With sufficient mid-level flow across northern
Utah, deep layer shear will be near 30-40kts, with the best shear
near the Utah/Idaho border closest to the trough. HREF ensemble
mean SBCAPE values are expected to average around 500-750 J/kg
across much of the state. Most of the state will also remain at
PWAT values near 0.70-1.2" through the day today.

Across the north, expect convection to develop through the
afternoon and into the evening. CAMS suggest one area of potential
development (fairly typical) will be across far eastern Nevada,
with these storms crossing the Salt Flats and potentially reaching
the Wasatch Front during the late afternoon or evening. Additional
convection may develop in-situ across northern Utah, especially
along the higher terrain and then quickly shift off into the
adjacent valleys. Given the modest deep layer shear, these storms
will be capable of brief heavy rainfall, gusty winds and small
hail.

Further south across central and southern Utah, there will be a
marked decrease in deep layer shear. Here, expect convection to
develop across the higher terrain and then shift eastward into
the adjacent valleys. Storm motions will favor down drainage
potential especially across the Swell and Capitol Reef. These
thunderstorms will be capable of heavy rainfall and will be
impacting areas that have seen quite a bit of precipitation over
the last few days...so infiltration will be somewhat minimal.

Any convection will gradually end by evening across southern and
eastern Utah...but may hang on through the night across
northeastern Utah where the best support for precipitation will be
colocated.

Upper level ridging will build into the area Friday into the
weekend, bringing a drying trend for Labor Day weekend.

.LONG TERM (After 12Z Sunday)...Ensemble and deterministic model
solutions are all reasonably well-clustered in the long term,
lending higher than average forecast confidence in the large-scale
feature evolution. At the onset of the long term period on Sunday
morning, models advertise high pressure ridge development across
the desert southwest. This ridge is expected to strengthen while
building northward across the Great Basin early next week, peaking
around 595-596dm on Tuesday and lingering across the Great Basin
on Wednesday. Ensemble clusters generally favor a stronger ridge
for the middle of next week, with 42 percent of the clusters
favoring stronger positive height anomalies across the Northern
Rockies and northern Great Basin on day 6, for example. Thus,
currently forecast temperatures may need to be nudged upwards in
the coming days should the stronger ridge solution indeed come to
fruition. The Tuesday- Thursday timeframe appear to be the best
window for possible future upward temperature trends. That said,
this ridge is a seasonably strong one, with positive height
anomalies progged to be around 1 standard deviation above normal,
per GEFS mean. Thus, while temperatures are forecast to be 5 to 10
degrees above normal for early September, they appear to remain
below record values.

The ridge is then expected to undergo a slow weakening trend
while slowly drifting southeastward, as supported by the current
most likely ensemble scenario. By the end of Day 7 (next Thursday)
the most likely forecast scenario places the ridge near the four-
corners region, which would allow for the development of modest
southerly flow across the region. At this time, no precipitation
is forecast in the long term until Wednesday or perhaps Thursday
-- and at this time any precipitation is forecast to remain
confined to isolated coverage across high terrain areas of
southern Utah.

&&

.AVIATION...KSLC...Southerly winds will remain in place through
Thursday morning. There is uncertainty regarding afternoon wind
direction, as there is a chance winds remain southerly through the
day. However, will continue to advertise a wind shift to 320
degrees around 21Z and continue to monitor for the potential for
continued southerly winds. Scattered CIGs are expected Thursday
afternoon with around a 30% chance for an isolated shower or
thunderstorm capable of gusty and erratic winds from 19Z-03Z.

REST OF UTAH AND SOUTHWEST WYOMING...Clouds will increase with
isolated showers and thunderstorms after 19Z Thursday, primarily
along and east of the I-15 corridor. Have added VCSH to all TAF
sites except KSGU for this afternoon and early evening. The best
chance for precipitation will be from 19Z-03Z. Brief MVFR
conditions are possible from a heavier shower or thunderstorm,
otherwise VFR conditions will be the rule.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

Kruse/ADeSmet

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

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php

Hazardous Weather Outlook
National Weather Service Salt Lake City UT
306 AM MDT Thu Sep 2 2021

UTZ101>131-WYZ021-031300-
Great Salt Lake Desert and Mountains-Tooele and Rush Valleys-
Eastern Box Elder County-Northern Wasatch Front-Salt Lake Valley-
Utah Valley-Cache Valley/Utah Portion-Wasatch Back-
Bear Lake and Bear River Valley-Wasatch Mountains I-80 North-
Wasatch Mountains South of I-80-Western Uinta Mountains-
Wasatch Plateau/Book Cliffs-Western Uinta Basin-
Western Millard and Juab Counties-Eastern Juab/Millard Counties-
Central Mountains-Sanpete Valley-Sevier Valley-Castle Country-
San Rafael Swell-Southwest Utah-Lower Washington County-
Zion National Park-Southern Mountains-Upper Sevier River Valleys-
Bryce Canyon Country-South Central Utah-
Capitol Reef National Park and Vicinity-Western Canyonlands-
Glen Canyon Recreation Area/Lake Powell-Southwest Wyoming-
306 AM MDT Thu Sep 2 2021

This Hazardous Weather Outlook is for the western two thirds of
Utah and southwest Wyoming.

.DAY ONE...Today and Tonight

Showers and thunderstorms are expected across northern Utah and
then central and southern Utah across the higher terrain and
adjacent valleys. Expect the threat of heavy rain for central and
southern Utah with gusty winds and small hail across northern
Utah.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information
about observed severe weather to the NWS while following all
local, state, and CDC guidelines.

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

For information on potential road travel impacts visit...
http://www.udottraffic.utah.gov/roadweatherforecast.aspx