Severe Thunderstorm Warning 101, NWS Riverton, WY

023 
WWUS55 KRIW 022118
SVSRIW

Severe Weather Statement
National Weather Service Riverton WY
318 PM MDT THU AUG 2 2018

WYC003-022145-
/O.CON.KRIW.SV.W.0101.000000T0000Z-180802T2145Z/
Big Horn-
318 PM MDT THU AUG 2 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 345 PM MDT
FOR SOUTHWESTERN BIG HORN COUNTY...

At 317 PM MDT, a severe thunderstorm was located 8 miles north of
Otto, or 12 miles west of Greybull, moving east southeast at 30 mph.

HAZARD...70 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

IMPACT...Expect considerable tree damage. Damage is likely to mobile 
         homes, roofs, and outbuildings.

This severe storm will be near...
  Greybull around 340 PM MDT.
  Basin and the Bighorn County Fair around 345 PM MDT.

Other locations impacted by this severe thunderstorm include Greybull
South Big Horn County Airport, Greybull Burlington Northern Santa Fe
Railroad Yard, Midway Golf Course, Burlington and Emblem.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

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

Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

If on or near lakes or streams, get away from the water and move 
indoors or inside a vehicle. remember, lightning can strike out to 
15 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 4441 10846 4468 10839 4470 10804 4471 10794
      4426 10808
TIME...MOT...LOC 2117Z 280DEG 27KT 4453 10831 

HAIL...0.75IN
WIND...70MPH
 
$$

13

Area Forecast Discussion
National Weather Service Riverton WY
1252 PM MDT Thu Aug 2 2018

.SHORT TERM...This evening through Sunday
Issued at 1223 PM MDT Thu Aug 2 2018

Monsoonal moisture in the sw will aid convection down there
spreading ne into the evening hours. Thermal trough/shortwave noted
on the upper air and satellite analysis this morning is moving into
ern ID and far swrn MT and this will be the focus for storms as it
moves into YNP through the afternoon hours and then spreads across
the north. A little better mid level westerlies and mid level
cooling will create the potential for a few stronger storms. A lot
of the area will have the threat of storms through the evening hours
with a few lingering overnight. Another round of storms is expected
Friday. The next approaching shortwave for Friday may draw another
round of monsoonal moisture nwd while some forcing across the north
with the trough and exiting jet may aid in storms across the far
north. The subtle front from today's wave washes out Friday before
the 'stronger' front drops down Friday night into Saturday hanging
around our central zones on Saturday. South of the boundary over
Sweetwater, Uinta and srn Lincoln County up to the Greens and
Rattlesnakes may have critical fire weather conds. The two critical
fuels zones 277 and 279 will have a fire weather watch for Saturday
from noon to 9 pm. If the front washes out further north, then 280
and even 283 could become critical. On Sunday, the system that is
currently out near 31-32N/142W will move onshore Saturday night and
move across us on Sunday. It could be an active day, especially
along and east of the divide as front remains in place while trough
approaches and dual jet structure develops in the nern zones.

.LONG TERM...Monday night through Thursday
Issued at 1223 PM MDT Thu Aug 2 2018

Pattern transition is forecast to be underway next week, as upper
low from the Gulf of Alaska dives south and cuts off over the
eastern Pacific, pumping up a ridge over the western U.S. Medium-
range models show an overall trend westward with this trough/ridge
pattern. This shift will put Wyoming under the influence of NW flow
aloft rather than under the dome of hot air; so forecast
temperatures, at least east of the Divide, have been trended
slightly cooler. Some adjustments further downward may be necessary
if this trend further westward of the ridge continues. A similar
pattern was responsible for severe weather outbreaks in late July;
however, models are placing mean surface trough and higher CAPES
along and east of Wyoming's eastern border, drier air over west and
central Wyoming. We have slight chances of thunderstorms over the
Bighorn Mountains on Monday; otherwise, dry conditions are expected
to prevail Monday through Thursday.

&&

.AVIATION...For the 00Z TAFS through 00Z Friday afternoon
Issued at 1223 PM MDT Thu Aug 2 2018

Showers and thunderstorms will continue through 06Z. Expect showers
and storms to persist through 06Z Fri in the central and east. VFR
conditions will occur at the terminal sites through the period.
Local MVFR conditions will occur with some of the stronger storms
due to heavy rain which would reduce visibility. Mountains will be
obscured at times. Another round of showers and thunderstorms is
likely tomorrow afternoon.

&&

.FIRE WEATHER...
Issued AT 1223 PM MDT Thu Aug 2 2018

...Fire Weather Watch Saturday from Noon to 9 pm for zones 277 and
279...

Scattered thunderstorms will move east across the area through this
evening. Isolated to widely scattered showers will continue through
the overnight hours, especially over southern portions. Another bout
of widely scattered to scattered thunderstorms will occur Friday
afternoon and evening. A Fire Weather Watch is in effect for fire
zones 277 and 279 from noon to 9 pm Saturday, due to very low RH
values and gusty winds up to 35 mph.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday afternoon through Saturday
evening for WYZ277-279.

&&

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

Hazardous Weather Outlook
National Weather Service Riverton WY
147 AM MDT Thu Aug 2 2018

WYZ001>020-022>030-031100-
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-
147 AM MDT Thu Aug 2 2018

This Hazardous Weather Outlook is for Western and Central
Wyoming.

.DAY ONE...Today and Tonight.

Scattered afternoon and evening thunderstorms. The main threat
will be gusty outflow winds of 50 to 55 mph possible. Warm
conditions and gusty winds will elevate fire weather conditions
across central and eastern portions this afternoon and early
evening.

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

Friday through Sunday...Warm with gusty west wind will elevated
fire weather conditions across southern Wyoming during the
afternoon and early evening. Isolated to scattered afternoon and
evening thunderstorms across mainly northern Wyoming.

.SPOTTER INFORMATION STATEMENT...

Spotters are urged to report wind gusts past 45 mph. Thank you.

Special Weather Statement
National Weather Service Riverton WY
229 PM MDT THU AUG 2 2018

WYZ005>007-022100-
Owl Creek and Bridger Mountains-Southeast Big Horn Basin-Southwest
Big Horn Basin-
229 PM MDT THU AUG 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN HOT SPRINGS AND
CENTRAL WASHAKIE COUNTIES UNTIL 300 PM MDT...

At 229 PM MDT, Doppler radar was tracking a strong thunderstorm over
Thermopolis, moving east at 15 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Thermopolis, Lucerne, Kirby, Hot Springs State Park, Hot Springs
County Fairgrounds, Legion Town And Country Golf Course and Hot Sprgs
County Thermopolis Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Occasional cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4378 10763 4340 10786 4340 10790 4339 10791
      4338 10790 4359 10846 4384 10832
TIME...MOT...LOC 2029Z 273DEG 12KT 4362 10825

Hulme

Special Weather Statement
National Weather Service Riverton WY
233 PM MDT THU AUG 2 2018

WYZ014-025-026-022100-
Wind River Mountains West-Upper Green River Basin-Upper Green River
Basin Foothills-
233 PM MDT THU AUG 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN SUBLETTE COUNTY
UNTIL 300 PM MDT...

At 233 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles southeast of Mesa Gas Field, or 15 miles south of Pinedale,
moving east at 30 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Boulder, Big Sandy, Wenz Field, Boulder Lake, Mesa Gas Field, Boulder
Lake Campground, Boulder Fish Rearing Station and Pinedale Ralph Wenz
Field.

LAT...LON 4252 11007 4278 11005 4289 10943 4257 10932
TIME...MOT...LOC 2033Z 259DEG 27KT 4265 10979

Hulme

Special Weather Statement
National Weather Service Riverton WY
243 PM MDT THU AUG 2 2018

WYZ012-013-022115-
Jackson Hole-Teton and Gros Ventre Mountains-
243 PM MDT THU AUG 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL TETON COUNTY UNTIL
315 PM MDT...

At 241 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles west of Mount Moran, or 8 miles northeast of Alta, moving
northeast at 15 mph.

Winds in excess of 30 mph will be possible with this storm.

Locations impacted include...
Alta, Moran Bay, Leigh Lake, Colter Bay Village, Mount Moran, Grand
Targhee Resort, Signal Mountain Lodge, Leek's Marina, Jackson Lake
Lodge and Targhee Village Golf Course.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Occasional cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

If on or near Jackson Lake or Leigh 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.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 4391 11105 4409 11078 4385 11055 4373 11105
TIME...MOT...LOC 2041Z 236DEG 15KT 4386 11093

Hulme

Special Weather Statement
National Weather Service Riverton WY
247 PM MDT THU AUG 2 2018

WYZ004-022115-
North Big Horn Basin-
247 PM MDT THU AUG 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN BIG HORN AND EAST
CENTRAL PARK COUNTIES UNTIL 315 PM MDT...

At 246 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles south of Garland, or 11 miles southeast of Powell, moving east
at 35 mph.

Wind gusts of 50 to 55 mph will be possible with this storm.

This storm will remain over mainly rural areas of northwestern Big
Horn and east central Park Counties, including the following
locations... Bighorn Canyon National Recreation Area and Powell Golf
Course.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If on or near any lakes or streams, 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 4494 10821 4491 10817 4455 10807 4454 10866
      4478 10873 4498 10822
TIME...MOT...LOC 2046Z 260DEG 31KT 4464 10858

13

Special Weather Statement
National Weather Service Riverton WY
247 PM MDT THU AUG 2 2018

WYZ017-022115-
Wind River Basin-
247 PM MDT THU AUG 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL FREMONT COUNTY UNTIL
315 PM MDT...

At 247 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles north of Riverton, moving east at 15 mph.

Winds in excess of 30 mph will be possible with this storm.

Locations impacted include...
Riverton, Shoshoni, Kinnear, Ocean Lake, Hidden Valley, Pavillion
Natural Gas Processing Plant, Riverton Country Club, Midvale,
Bonneville, Fremont County Fairgrounds and Riverton Regional Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 4314 10875 4342 10849 4324 10792 4291 10827
TIME...MOT...LOC 2047Z 286DEG 11KT 4315 10844

Hulme

Special Weather Statement
National Weather Service Riverton WY
252 PM MDT THU AUG 2 2018

WYZ006-022115-
Southeast Big Horn Basin-
252 PM MDT THU AUG 2 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL WASHAKIE COUNTY
UNTIL 315 PM MDT...

At 252 PM MDT, Doppler radar was tracking a strong thunderstorm over
Worland, moving east at 15 mph.

Winds in excess of 30 mph will be possible with this storm.

Locations impacted include...
Worland, Winchester, Worland Municipal Airport, Wyoming Boys School
and Washakie County Fairgrounds.

LAT...LON 4407 10760 4378 10763 4380 10796 4382 10796
      4382 10819 4414 10804
TIME...MOT...LOC 2052Z 286DEG 11KT 4400 10791

Hulme