Special Weather Statement, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
1008 AM MDT Sun Jul 25 2021

.SYNOPSIS...Drier air will remain over northern Utah and southwest
Wyoming today. Deep moisture will linger across southern Utah,
leading to showers and thunderstorms with localized heavy rainfall.
The moisture will spread northward again Monday into Tuesday.
Unsettled conditions will continue for much of the week.

&&

.DISCUSSION...High pressure remains centered just west of Utah and
southwest Wyoming this morning as an upper low moves across
Arizona. North to northeast flow aloft has allowed for a hot,
dry, and smoky airmass to move across northern Utah, with some
additional reduction in visibility and air quality anticipated
today. Meanwhile, deeper moisture lingers over southern Utah,
particularly the southwest corner where PWs are approaching 1.4
inch. Anticipating another round of showers and thunderstorms
developing this afternoon as daytime heating increases
instability, with any storms that develop capable of producing
heavy rain that could result in flash flooding. Going Flash Flood
Watch covers the highest threat area well.

By Monday, the Arizona low is expected to reach the southern
California coast, shifting the ridge axis just east of the area
and allowing a more southerly flow to develop. This will allow the
moisture pooled over the Desert Southwest to spread northward,
into central Utah by Monday afternoon and across much of the area
by Tuesday. This will result in a more widespread threat of
convection and will also act to decrease the amount of smoke over
northern Utah. Little change in the pattern is anticipated during
the middle to latter part of the week, so unsettled conditions are
expected to continue.

No updates expected to the forecast this morning.

&&

.AVIATION...KSLC...VFR conditions are expected throughout the day
at the SLC terminal with mostly clear skies. Smoke in the air will
result in some reduction in visibility, with a 20 percent chance
of periods of MVFR conditions late this afternoon into early this
evening. Southeast winds are expected to shift to the northwest
between 18Z and 20Z.

Rest of Utah and southwest Wyoming...Showers and thunderstorms are
expected to develop across southern Utah this afternoon into early
this evening. Gusty and erratic winds can be expected in and
around thunderstorm areas. Brief intermittent MVFR conditions can
be expected at terminals directly impacted by thunderstorms,
otherwise expect VFR conditions to persist outside thunderstorm
areas. Over northern Utah and southwest Wyoming, there is a 30
percent chance that smoke will result in some pockets of MVFR
conditions late this afternoon into early this evening, with VFR
conditions prevailing otherwise.

&&

.FIRE WEATHER...A moist airmass remains in place across southern
Utah today. This will lead to scattered wet thunderstorms across the
area this afternoon into this evening, with the strongest storms
expected across southwest Utah. Meanwhile, northern Utah will
remain hot, dry, and stable. Southerly flow will return tomorrow
as high pressure rebounds and shifts east. This will spread
moisture back northward, through at least central Utah tomorrow
and northern Utah by Tuesday. Unsettled weather will then continue
through the week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flash Flood Watch through this evening for UTZ123>125.

WY...None.
&&

Traphagan

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
618 AM MDT Sun Jul 25 2021

UTZ101>131-WYZ021-261300-
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-
618 AM MDT Sun Jul 25 2021

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

.DAY ONE...Today and Tonight

Showers and thunderstorms capable of producing heavy rain, gusty
winds, and hail will once again occur this afternoon and evening.
The strongest storms are expected across southwest Utah where a
potential for flash flooding exists, especially in prone areas
such as slot canyons, burn scars, areas of steep terrain, and
normally dry washes and streams.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Moisture will spread northward Monday into Tuesday. Daily showers
and thunderstorms capable of heavy rain, gusty winds and small
hail will occur each afternoon and evening across much of the
forecast area through the week.

.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

Special Weather Statement
National Weather Service Salt Lake City UT
249 PM MDT Sun Jul 25 2021

UTZ125-126-252115-
Upper Sevier River Valleys UT-Southern Mountains UT-
249 PM MDT Sun Jul 25 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN GARFIELD AND
NORTHEASTERN IRON COUNTIES UNTIL 315 PM MDT...

At 248 PM MDT, National Weather Service Doppler radar indicated a
strong thunderstorm 14 miles southwest of Junction...moving west at
15 mph.

Half inch hail and wind gusts up to 50 mph will be possible.

This storm will remain over mainly rural areas of northwestern
Garfield and northeastern Iron Counties.

This includes the following highways...
 Interstate 15 near mile marker 100.
 US Route 89 between mile markers 138 and 155.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If threatening weather approaches, take shelter in a sturdy building.

Heavy rainfall is also occurring with this storm, and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio and
available television stations for additional information and possible
warnings from the National Weather Service.

&&

LAT...LON 3814 11225 3796 11222 3788 11259 3814 11263
TIME...MOT...LOC 2048Z 082DEG 15KT 3804 11234

ND