Special Weather Statement, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
1016 AM MDT Mon Aug 7 2017

.SYNOPSIS...Weakening high pressure aloft centered over the
Great Basin will lead to an increase in thunderstorm activity
across mainly northern and central Utah for the first half of the
week.

&&

.DISCUSSION...A low-amplitude upper ridge across the interior west
with an upstream trough over Oregon/northern California will
maintain a west-southwest flow aloft across the Great Basin
through midweek. PWAT values will remain somewhat elevated across
the region, though values will show a modest decrease across the
far south the next couple of days.

Convective activity will likely concentrate across the northern
and central portion of the state through midweek. The main driving
force will be the various weak shortwaves ejecting out of the
upper trough over northern California. One such feature moving
into northeast Utah will produce light showers before exiting the
area early this afternoon. A second feature will bring a few
showers/isolated thunderstorms to northwest Utah late this
morning and through the afternoon hours.

Nocturnal convection will likely develop along a weak dynamic
feature moving east-northeast out of Nevada and into west-central
Utah this evening. Sufficient instability and dynamic lift will
exist overnight through Tuesday morning to maintain convection
northern and portions of central Utah.

Northern Utah will likely become the most active area for
convection late Tuesday/Tuesday night as the flow turns more
westerly ahead of a somewhat stronger shortwave Tuesday night.
Central and southern Utah will see convection, though this
activity will be tied more closely to the terrain during the
afternoon/early evening hours.

A slight building of heights across southern/central Utah
Wednesday will further reduce convection, and confine what
develops to the higher terrain. Northern Utah/southwest Wyoming
will remain the focus for convective activity as PWAT values
remain elevated and subsequent shortwaves track east through the
area.

.AVIATION...Southerly winds at the SLC terminal are expected to
shift to the northwest between 18-20Z. Convection is expected to
develop and impact the Salt Lake area later this afternoon into this
evening with a 30% chance of gusty and erratic outflow winds at the
SLC terminal between 21-01Z.

&&

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

PUBLIC...CONGER
AVIATION...KRUSE

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
527 AM MDT Mon Aug 7 2017

UTZ001>016-019>021-517-518-WYZ021-081300-
Cache Valley/Utah Portion-Northern Wasatch Front-
Salt Lake and Tooele Valleys-Southern Wasatch Front-
Great Salt Lake Desert and Mountains-Wasatch Mountain Valleys-
Wasatch Mountains I-80 North-Wasatch Mountains South of I-80-
Western Uinta Mountains-Wasatch Plateau/Book Cliffs-
Western Uinta Basin-Castle Country-San Rafael Swell-
Sanpete/Sevier Valleys-West Central Utah-Southwest Utah-
Utahs Dixie and Zion National Park-South Central Utah-
Glen Canyon Recreation Area/Lake Powell-Central Mountains-
Southern Mountains-Southwest Wyoming-
527 AM MDT Mon Aug 7 2017

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

.DAY ONE...Today and Tonight

Scattered to numerous showers and thunderstorms are expected
across the central through northern outlook area this afternoon
through this evening, while storms will be less numerous across
the far south. Some of the storms could produce locally heavy
rainfall. Gusty winds may emanate from the storms late this
afternoon and evening.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Thunderstorm coverage should become more confined to the northern
portions of the outlook area Tuesday into Wednesday. Moisture
could gradually return to the south by the weekend.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to standard operating procedures.

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
340 PM MDT MON AUG 7 2017

WYZ021-072215-
Southwest Wyoming WY-
340 PM MDT MON AUG 7 2017

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL UINTA COUNTY UNTIL 415 PM
MDT...

At 339 PM MDT, National Weather Service doppler radar indicated a
strong thunderstorm 10 miles east of Evanston...moving northeast at
30 mph. This storm will cross I-80 shortly.

Penny size hail and winds in excess of 40 mph will be possible.

Locations impacted include...
Carter, Ragen and Leroy.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4117 11071 4127 11091 4154 11070 4148 11038
TIME...MOT...LOC 2139Z 213DEG 24KT 4129 11076

NC

Special Weather Statement
National Weather Service Salt Lake City UT
347 PM MDT MON AUG 7 2017

UTZ007-072215-
Wasatch Mountains I-80 North UT-
347 PM MDT MON AUG 7 2017

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL CACHE AND
NORTHWESTERN RICH COUNTIES UNTIL 415 PM MDT...

At 347 PM MDT, National Weather Service doppler radar indicated a
strong thunderstorm 11 miles southwest of Laketown...moving northeast
at 5 mph.

Penny to nickel size hail and wind gusts of 40 to 55 mph will be
possible.

Locations impacted include...
Laketown, Garden and Meadowville.

Another severe thunderstorm is located to the northeast of this
storm, near Laketown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4160 11140 4170 11162 4191 11149 4177 11118
TIME...MOT...LOC 2147Z 223DEG 6KT 4170 11146

CRK

Special Weather Statement
National Weather Service Salt Lake City UT
409 PM MDT MON AUG 7 2017

UTZ007-072300-
Wasatch Mountains I-80 North UT-
409 PM MDT MON AUG 7 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN CACHE AND NORTHERN
RICH COUNTIES UNTIL 500 PM MDT...

At 407 PM MDT, National Weather Service Doppler radar indicated a
strong thunderstorm near Laketown...moving northeast at 5 mph.
Additional thunderstorms are located to the southwest of Laketown
over northern Rich county.

Penny to nickel size hail and wind gusts of 40 to 55 mph will be
possible.

Locations impacted include...
Randolph, Laketown, Garden City, Garden, Meadowville, Pickelville and
Lakota.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

If on or near Bear Lake, get out of the water and move indoors or
inside a vehicle. Remember, lightning can strike out to 10 miles
from the parent thunderstorm. If you can hear thunder, you are close
enough to be struck by lightning. Move to safe shelter now! Do not
be caught on the water in a thunderstorm.

&&

LAT...LON 4168 11106 4157 11144 4186 11166 4200 11141
      4200 11105
TIME...MOT...LOC 2207Z 228DEG 5KT 4187 11133

CRK