Severe Thunderstorm Warning 47, NWS Riverton, WY

Area Forecast Discussion
National Weather Service Riverton WY
148 PM MDT Thu Jul 4 2019

.SHORT TERM...This afternoon through Friday
Issued at 1051 AM MDT Thu Jul 4 2019

Atmosphere starting to percolate this afternoon, as local
temperatures begin to reach the convective temperature. Good shear
and CAPE values around 1500 bring a threat for strong to severe
thunderstorms through midevening. Main threat is large hail, but
isolated tornadoes are also a threat early this evening.

Axis of the H5 trough sweeps toward Wyoming overnight, adding a
final surge of midlevel lift to the region. Showers and a few
thunderstorms are expected to redevelop and spread northeastward
overnight, mainly for west Wyoming. As the vort rotates through
to the northeast Friday morning, and few lingering showers and
thunderstorms could be continuing across the far northern zones
into the early afternoon. Activity should be ending south to north
through the day.

.LONG TERM...Friday night through Wednesday
Issued at 1051 AM MDT Thu Jul 4 2019

Showers and thunderstorms will linger in the north and east Friday
night as a shortwave moves out of the area. This activity should
will dissipate quickly after midnight. With continued southwesterly
flow, areas of south and southwest Wyoming will stay in a drier
airmass on Saturday, with relative humidities dropping into the
teens. By Sunday the low humidities will spread throughout southern
and central Wyoming. Gusty winds will help to elevate fire weather
conditions at times through the weekend, especially on Sunday
afternoon when winds will increase in response to a tightening
pressure gradient. Additionally, temperatures will warm Saturday
onward as stronger southwest flow advects a warmer airmass into the
area. There still looks to be enough forcing and moisture for
continued rain chances during the weekend but most areas should
remain dry. Warmer temperatures will continue into next week, with
continued afternoon rain chances mainly across the north as weak
shortwave move through Montana.

&&

.AVIATION...For the 18Z TAFS through 18Z Friday afternoon
Issued at 1051 AM MDT Thu Jul 4 2019

Thunderstorm activity will be on the increase this afternoon for
all TAF sites, except maybe RKS. First wave of thunderstorms still
looking to happen between now and 01z. A another shortwave sweeps
toward Wyoming this evening, another round of showers and
isolated thunderstorms is expected to develop roughly around
midnight, impacting all locations. This wave will sweep to the
northeast on Friday, leaving most areas mostly clear. A few
lingering thunderstorms may develop on the higher elevations of
the Big Horn and Absaroka ranges, possibly drifting toward
COD/WRL/BYG during the afternoon.

&&

.FIRE WEATHER...
Issued AT 1051 AM MDT Thu Jul 4 2019

Isolated to scattered thunderstorms will occur over much of the area
this afternoon and evening. Some thunderstorms could be severe with
large hail, high winds, along with torrential rainfall with the
greatest risk across the southern Bighorn Basin, Fremont, Natrona,
and S. Johnson counties. The highest fire weather conditions this
afternoon will be in southeast Sweetwater County with RHs in the mid
to upper teens and southwesterly winds about 20 mph gusting to
around 30 mph. On Friday, drier conditions are expected over the far
west and southwest. Winds will be gusty but not over the critical
threshold. Thunderstorms are expected again over the rest of the
area.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...Straub
LONG TERM...Hulme
AVIATION...Straub
FIRE WEATHER...Hulme

Hazardous Weather Outlook
National Weather Service Riverton WY
448 AM MDT Thu Jul 4 2019

WYZ001>020-022>030-051200-
Yellowstone National Park-Absaroka Mountains-Cody Foothills-
North Big Horn Basin-Southwest Big Horn Basin-
Southeast Big Horn Basin-Owl Creek and Bridger Mountains-
Bighorn Mountains West-Bighorn Mountains Southeast-
Northeast Johnson County-Southeast Johnson County-
Teton and Gros Ventre Mountains-Jackson Hole-
Wind River Mountains West-Wind River Mountains East-
Upper Wind River Basin-Wind River Basin-Lander Foothills-
Green Mountains and Rattlesnake Range-
Natrona County Lower Elevations-Casper Mountain-Star Valley-
Salt River and Wyoming Ranges-Upper Green River Basin Foothills-
Upper Green River Basin-South Lincoln County-
Rock Springs and Green River-Flaming Gorge-East Sweetwater County-
448 AM MDT Thu Jul 4 2019

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight.

Isolated to scattered thunderstorms. Some storms could be severe
especially across the southern Bighorn Basin, Fremont County,
Natrona County, southern Johnson County and surrounding mountains.
Large hail will be the primary hazard, but damaging winds and an
isolated tornado could occur.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...Isolated to scattered thunderstorms over the north and
east.

Saturday...Strong thunderstorms are possible over the north and
east.

.SPOTTER INFORMATION STATEMENT...

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

TEAM RIVERTON

Special Weather Statement
National Weather Service Riverton WY
446 PM MDT Thu Jul 4 2019

WYZ007-017-042315-
Owl Creek and Bridger Mountains-Wind River Basin-
446 PM MDT Thu Jul 4 2019

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN FREMONT COUNTY UNTIL
515 PM MDT...

At 446 PM MDT, Doppler radar was tracking a strong thunderstorm 9
miles northeast of Pavillion, moving east at 25 mph.

Nickel size hail and winds in excess of 30 mph will be possible with
this storm.

This storm will remain over mainly rural areas of northeastern
Fremont County.

A Severe Thunderstorm Watch remains in effect until 1000 PM MDT for
central Wyoming.

LAT...LON 4319 10878 4330 10880 4350 10831 4347 10830
      4346 10819 4328 10811
TIME...MOT...LOC 2246Z 251DEG 22KT 4333 10854

Hulme

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
515 PM MDT THU JUL 4 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0515 PM     HAIL             OCEAN LAKE              43.18N 108.61W
07/04/2019  M0.25 INCH       FREMONT            WY   PUBLIC

&&

GSWANSON

Special Weather Statement
National Weather Service Riverton WY
525 PM MDT Thu Jul 4 2019

WYZ007-017-050000-
Owl Creek and Bridger Mountains-Wind River Basin-
525 PM MDT Thu Jul 4 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL HOT SPRINGS AND
EAST CENTRAL FREMONT COUNTIES UNTIL 600 PM MDT...

At 524 PM MDT, Doppler radar was tracking a strong thunderstorm 11
miles southwest of Boysen State Park, which is 14 miles west of
Shoshoni, moving east at 25 mph.

Penny size hail and wind gusts up to 50 mph will be possible with
this storm.

This strong thunderstorm will be near...
  Shoshoni around 555 PM MDT.

Other locations impacted by this storm include Midvale and
Bonneville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Riverton.

If on or near Boysen Reservoir, 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.

&&

A Severe Thunderstorm Watch remains in effect until 1000 PM MDT for
central Wyoming.

LAT...LON 4320 10855 4339 10865 4353 10811 4323 10798
TIME...MOT...LOC 2324Z 256DEG 20KT 4331 10837

TL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
550 PM MDT THU JUL 4 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0547 PM     HAIL             18 N CASPER             43.09N 106.33W
07/04/2019  M0.75 INCH       NATRONA            WY   TRAINED SPOTTER

            DIME SIZED HAIL.

&&

GSWANSON

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