Flash Flood Warning 15, NWS Riverton, WY

693 
WGUS75 KRIW 060221
FFSRIW

Flash Flood Statement
National Weather Service Riverton WY
821 PM MDT THU JUL 5 2018

WYC043-060415-
/O.CON.KRIW.FF.W.0015.000000T0000Z-180706T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washakie-
821 PM MDT THU JUL 5 2018

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1015 PM MDT FOR
CENTRAL WASHAKIE COUNTY...

At 814 PM MDT, Doppler radar continued to indicate thunderstorms 
producing heavy rain across central Washakie County. Doppler radar 
estimates that between 2 and 3 inches of rain has fallen in the Joe 
Henry Fork and Hawks Nest Fork drainages. Both of the drainages flow 
into the East Fork of the Nowater Creek.

Another Flash flood warning remains in effect until 1045 PM for 
areas along Highway 16 about 10 miles east of Worland.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, country roads, farmland, and other low lying
spots.

In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.

&&

LAT...LON 4388 10757 4378 10756 4376 10775 4385 10782
      4391 10796 4393 10799 4395 10796 4394 10763

$$

21

437 
WGUS75 KRIW 060335
FFSRIW

Flash Flood Statement
National Weather Service Riverton WY
935 PM MDT THU JUL 5 2018

WYC043-060343-
/O.CAN.KRIW.FF.W.0015.000000T0000Z-180706T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washakie-
935 PM MDT THU JUL 5 2018

...THE FLASH FLOOD WARNING FOR CENTRAL WASHAKIE COUNTY IS
CANCELLED...

The heavy rain has ended and any flood waters are expected to 
recede. Please be careful along small streams across central and 
eastern Washakie County, as they will continue to run high and swift 
in places tonight.

LAT...LON 4388 10757 4378 10756 4376 10775 4385 10782
      4391 10796 4393 10799 4395 10796 4394 10763

$$

21

Area Forecast Discussion
National Weather Service Riverton WY
355 PM MDT Thu Jul 5 2018

.SHORT TERM...(This evening through Friday)
Issued at 130 PM MDT Thu Jul 5 2018

Generally unstable conditions this afternoon and evening will
continue isolated to scattered thunderstorms over western and
central Wyoming. Some stronger storms are possible around the
Bighorn Mountains and over Johnson and Natrona counties, where
surface-based CAPE values are over 1500 J/kg and lifted indices
are less than -4C. During the afternoon hours, the primary threat
from the storms will be gusty outflow wind. As the afternoon
progresses and into the evening hours, brief heavy rain and small
to medium hail will also be a threat. The short term model
guidance is suggesting some heavy precipitation rates along the
eastern foothills of the Bighorn mountains in Johnson county and
northwestern Natrona county. As the convection moves to NE WY this
evening, easterly outflow wind will push back into the Wind River
and southern Big Horn Basins. Possibility for some low- to mid-
level ceilings over Johnson and Natrona counties with this
pattern.

Skies will clear more after sunrise Friday morning with some
partly cloudy conditions in the afternoon, with Friday afternoon
having a very slight chance of thunderstorms over the higher
terrain, and SW Sweetwater county off the Uinta mountains.
Temperatures should warm a few degrees over Thursday with the
700mb temperatures warming by 2-3C. Friday afternoon will also be
a bit breezier too over SW WY.

.LONG TERM...(Friday night through Thursday)
Issued at 130 PM MDT Thu Jul 5 2018

A high pressure ridge with southwest flow aloft over the
area will bring generally dry and hot weather conditions
Friday night and Saturday.  Record to near record high
temperatures are expected on Saturday. Some Pacific moisture
will move up from the great basin on Sunday supporting
isolated showers and thunderstorms mainly over the mountains.
Cloud cover and precipitation will cool temperatures slightly
on Sunday about 5 degrees. The Pacific moisture will continue
to surge north from the great basin with increasing clouds,
showers and thunderstorms on Monday and Tuesday with slight
cooling continuing. Then the moisture will become more limited
with decreasing showers and thunderstorms on Wednesday with mostly
dry conditions on Thursday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday afternoon)
Issued at 355 PM MDT Thu Jul 5 2018

VFR conditions expected throughout the forecast period (next 24
hours), although brief local MVFR possible under and around stronger
thunderstorms this evening.  Isolated to scattered showers and
thunderstorms are expected through this evening over much of the
area. Stronger storms possible over eastern Bighorn Basin, and into
Natrona and Johnson counties could produce gusty outflow over 40+
kts brief heavy rain, and small hail. Storms should move northeast
and be out of the area by 03-04Z/Fri. Scattered mid-level clouds
overnight possible from KCPR-KBYG. Friday to see clearing with
breezy SW flow with very isolated thunderstorms.

&&

.FIRE WEATHER...
Issued AT 130 PM MDT Thu Jul 5 2018

Isolated to scattered showers and thunderstorms will continue
into the evening hours, particularly over central to NE WY. The
stronger storms will likely produce outflows over 40 mph along
with brief heavy rain and some small hail. Lightning from
relatively high-based thunderstorms is also a concern as fuels are
drying out more, and some lower elevations fuel in central WY are
critical. This evening will likely see easterly outflow across
central WY as well, that will possibly push into southern WY.
Expect warmer and drier conditions on Friday with only a very
slight chance of thunderstorms over the higher terrain, with most
lower elevations in the teens for afternoon RH values. Winds will
remain below critical values, with some gusty flow up to 25 mph
across SW WY. Saturday will continue the very warm and dry
conditions, with a weak cool front pushing into northern WY late
in the day.

&&

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

&&

SHORT TERM...McDonald/Bourque
LONG TERM...Baker
AVIATION...McDonald/Bourque
FIRE WEATHER...McDonald/Bourque

Hazardous Weather Outlook
National Weather Service Riverton WY
210 AM MDT Thu Jul 5 2018

WYZ001>020-022>030-060815-
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-
210 AM MDT Thu Jul 5 2018

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight

Isolated afternoon and evening thunderstorms in northern and
central Wyoming.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Friday and Saturday...Highs from the mid 90s to low 100s in the
lower elevations East of the Divide.

Sunday through Wednesday...Isolated thunderstorms, mainly across
the north and west.

.SPOTTER INFORMATION STATEMENT...

Spotter activation are urged to report hail and wind gusts past 45
mph. Thank you.

Special Weather Statement
National Weather Service Riverton WY
541 PM MDT THU JUL 5 2018

WYZ002-003-005-007-060045-
Owl Creek and Bridger Mountains-Cody Foothills-Southwest Big Horn
Basin-Absaroka Mountains-
541 PM MDT THU JUL 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN HOT SPRINGS AND
SOUTHEASTERN PARK COUNTIES UNTIL 645 PM MDT...

At 537 PM MDT, Doppler radar was tracking a strong thunderstorms
across the southern Absaroka mountains generally south of Meeteetse,
and west of Grass Creek. These thunderstorms are moving north at 10
to 20 mph.

Very heavy rainfall, dime size hail and winds in excess of 40 mph
are possible with these storms.

Locations impacted by this storm include Sunshine Reservoir and
Grass Creek, and Meeteetse.

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.

Frequent 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 4369 10883 4402 10934 4431 10889 4398 10849
TIME...MOT...LOC 2337Z 201DEG 19KT 4393 10900

21

Special Weather Statement
National Weather Service Riverton WY
616 PM MDT THU JUL 5 2018

WYZ011-020-060100-
Southeast Johnson County-Natrona County Lower Elevations-
616 PM MDT THU JUL 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN JOHNSON AND NORTH
CENTRAL NATRONA COUNTIES UNTIL 700 PM MDT...

At 614 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles northwest of Midwest moving north at 40 mph.

One-half inch diameter hail, brief heavy rain, and wind gusts of 30
to 40 mph will be possible with this storm.

This strong thunderstorm will be near...
  Linch around 630 PM MDT.
  Sussex around 640 PM MDT.
  Fort Reno Historical Site around 650 PM MDT.

LAT...LON 4339 10625 4342 10659 4397 10655 4393 10604
TIME...MOT...LOC 0014Z 187DEG 35KT 4350 10638

CNJ

Special Weather Statement
National Weather Service Riverton WY
619 PM MDT THU JUL 5 2018

WYZ007-009-020-060045-
Owl Creek and Bridger Mountains-Bighorn Mountains Southeast-Natrona
County Lower Elevations-
619 PM MDT THU JUL 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN NATRONA COUNTY UNTIL
645 PM MDT...

At 618 PM MDT, Doppler radar was tracking a strong thunderstorm 9
miles north of Hiland moving north at 15 mph.

Hail up to one-half inch diameter, wind gusts around 40 mph, and
brief heavy rain will be possible with this storm.

This storm will remain over mainly rural areas of northwestern
Natrona County, including the following locations... Arminto.

LAT...LON 4316 10718 4318 10738 4344 10740 4344 10738
      4343 10737 4343 10728 4345 10726 4345 10702
TIME...MOT...LOC 0018Z 201DEG 13KT 4326 10729

CNJ

Special Weather Statement
National Weather Service Riverton WY
635 PM MDT THU JUL 5 2018

WYZ006-008-060115-
Southeast Big Horn Basin-Bighorn Mountains West-
635 PM MDT THU JUL 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN WASHAKIE COUNTY
UNTIL 715 PM MDT...

At 634 PM MDT, Doppler radar was tracking a strong thunderstorm 15
miles southwest of Ten Sleep, moving northeast at 30 mph.

Hail up to one-half inch diameter, brief heavy rain, and winds gusts
of 30 to 40 mph will be possible with this storm.

This strong thunderstorm will be near...
  Ten Sleep around 705 PM MDT.
  Tensleep Canyon around 710 PM MDT.

Other locations impacted by this storm include Wigwam Fish Rearing
Station and State Highway 434 around Ten Sleep.

LAT...LON 4374 10756 4385 10788 4413 10767 4412 10723
TIME...MOT...LOC 0033Z 213DEG 27KT 4386 10765

CNJ

Special Weather Statement
National Weather Service Riverton WY
641 PM MDT THU JUL 5 2018

WYZ006>009-060115-
Owl Creek and Bridger Mountains-Southeast Big Horn Basin-Bighorn
Mountains Southeast-Bighorn Mountains West-
641 PM MDT THU JUL 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN NATRONA AND
SOUTHEASTERN WASHAKIE COUNTIES UNTIL 715 PM MDT...

At 640 PM MDT, Doppler radar was tracking a strong thunderstorm near
Cottonwood Pass, or 35 miles northeast of Shoshoni, moving northeast
at 35 mph.

Very heavy rainfall, dime size hail and wind gusts up to 50 mph will
be possible with this storm.

This storm will remain over mainly rural areas of northwestern
Natrona and southeastern Washakie Counties.

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.

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.

&&

LAT...LON 4335 10747 4338 10753 4347 10758 4368 10758
      4368 10735 4356 10712
TIME...MOT...LOC 0040Z 218DEG 30KT 4347 10748

21

Special Weather Statement
National Weather Service Riverton WY
645 PM MDT THU JUL 5 2018

WYZ011-060130-
Southeast Johnson County-
645 PM MDT THU JUL 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN JOHNSON COUNTY UNTIL
730 PM MDT...

At 644 PM MDT, Doppler radar was tracking a strong thunderstorm near
Hole In The Wall, or 10 miles southwest of Kaycee, moving northeast
at 20 mph.

Hail up to one-half inch diameter, wind gusts of 35 to 45 mph, and
brief heavy rain will be possible with this storm.

This strong thunderstorm will be near...
  Kaycee around 720 PM MDT.

Other impacted locations include TTT Ranch Road.

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.

&&

LAT...LON 4349 10655 4349 10682 4350 10684 4351 10688
      4354 10688 4354 10690 4355 10691 4371 10684
      4371 10683 4373 10683 4398 10672 4395 10630
TIME...MOT...LOC 0044Z 225DEG 17KT 4359 10677

CNJ