Alert archive / Wyoming / Special Weather Statements in 2018

Special Weather Statement, NWS Riverton, WY

May 27, 2018Big Horn County, Wyoming

NWS Riverton, WY issued this special weather statement at May 27, 2018, 5:21 PM MDT for Big Horn County, Wyoming. It was in force for 39 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: May 27, 2018, 5:21 PM MDT (23:21 UTC)
Expired: May 27, 2018, 6:00 PM MDT
In force: 39 min
Issued by: NWS Riverton, WY

County Big Horn County, WY

The radar

The Riverton/Lander radar (KRIW), 114 km from the middle of the area, began a volume at 23:22 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Riverton, WY (KRIW), launched 12:00Z, 11.4 hours before the alert went out and 113 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 52 J/kg
Mixed-layer CIN: -196 J/kg
Mixed-layer LCL: 1809 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 58 m²/s²
0-3 km storm-relative helicity: 145 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Riverton, WY wrote its last area forecast discussion before this special weather statement went out at May 27, 4:43 PM MDT, 38 minutes earlier.

Area forecast discussion, May 27, 4:43 PM MDT, 38 minutes before

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Hazardous weather outlook, May 27, 2:42 AM MDT, 14 hours 39 minutes before

Hazardous Weather Outlook
National Weather Service Riverton WY
242 AM MDT Sun May 27 2018

WYZ001>020-022>030-281100-
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-
242 AM MDT Sun May 27 2018

...Flash Flood Watch in effect from noon through this evening for
Natrona and Johnson Counties...

...Flood Watch from this morning through Monday afternoon...

This Hazardous Weather Outlook is for Western and Central Wyoming.

.DAY ONE...Today and Tonight

Scattered showers and thunderstorms developing over most
of the area. Locally heavy rainfall is possible and will elevate
the flood threat along rivers and creeks already running high from
snowmelt. Isolated strong to severe thunderstorms are possible.

.DAYS TWO THROUGH SEVEN...Memorial Day through Saturday

Memorial Day...Scattered showers and thunderstorms developing
over most of the area. Locally heavy rain may elevate the flood
threat along rivers and creeks already running high from snowmelt.

Tuesday...Isolated to scattered showers and thunderstorms across
the area.

Thursday and Friday...Isolated to scattered showers and
thunderstorms mainly in the north and west.

.SPOTTER INFORMATION STATEMENT...

Spotters are urged to report hail, wind gusts past 45 mph and any
flooding. Thank you.

In the hours before

Special weather statement, May 27, 3:13 PM MDT, 2 hours 8 minutes before

Special Weather Statement
National Weather Service Riverton WY
313 PM MDT SUN MAY 27 2018

WYZ019-020-022-272200-
Green Mountains and Rattlesnake Range-Casper Mountain-Natrona County
Lower Elevations-
313 PM MDT SUN MAY 27 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN NATRONA COUNTY UNTIL 400
PM MDT...

At 313 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles northwest of Alcova, which is 30 miles southwest of Casper,
moving north at 15 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Alcova, Ervay, Bates Hole, Emigrant Gap, Independence Rock, Devil's
Gate, Austin Creek Natural Gas Processing Plant, Bessemer Bend,
Pathfinder Dam, Alcova Dam and Casper Mountain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

A severe thunderstorm watch remains in effect until 800 PM MDT for
central Wyoming.

LAT...LON 4243 10726 4291 10744 4287 10648 4243 10631
TIME...MOT...LOC 2113Z 167DEG 13KT 4266 10687

Hulme

Special weather statement, May 27, 3:22 PM MDT, 1 hour 59 minutes before

Special Weather Statement
National Weather Service Riverton WY
322 PM MDT SUN MAY 27 2018

WYZ002-005-007-016-017-272215-
Owl Creek and Bridger Mountains-Wind River Basin-Upper Wind River
Basin-Southwest Big Horn Basin-Absaroka Mountains-
322 PM MDT SUN MAY 27 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN HOT SPRINGS AND
NORTHEASTERN FREMONT COUNTIES UNTIL 415 PM MDT...

At 320 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from around Diversion Dam Rest Area to Boysen State
Park to Moneta. Movement was north at 20 to 25 mph.

Heavy rainfall of one-half inch, pea-sized hail, wind gusts to 40
mph, and dangerous lightning are all likely with these storms.

These thunderstorms will impact the Wind River Canyon and
Thermopolis. Mud and rock may be on the road surface in the Wind
River Canyon as the one-half inch of rain has been falling in about
30 minutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Very heavy rainfall is also occurring with these storms, and may
lead to localized flooding. Do not drive your vehicle through
flooded roadways.

&&

A severe thunderstorm watch remains in effect until 800 PM MDT for
central Wyoming.

LAT...LON 4371 10932 4374 10840 4337 10752 4278 10787
      4324 10848 4324 10917
TIME...MOT...LOC 2119Z 183DEG 24KT 4338 10899 4341 10844 4309 10786

CNJ

Local storm report, May 27, 4:14 PM MDT, 1 hour 7 minutes before

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Special weather statement, May 27, 4:18 PM MDT, 1 hour 3 minutes before

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Local storm report, May 27, 5:17 PM MDT, 4 minutes before

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Special weather statement, May 27, 5:21 PM MDT, 0 minutes before

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The office that day

Everything else NWS Riverton, WY issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 26, 6:49 PM MDT	Special Weather Statement	RIW	Park	41 min
May 26, 11:00 PM MDT	Areal Flood Warning	RIW	Big Horn	12 hr
May 26, 11:21 PM MDT	Areal Flood Warning	RIW	Washakie	12 hr
May 27, 1:46 AM MDT	Flash Flood Watch	RIW	Johnson, Natrona	25 hr
May 27, 9:40 AM MDT	Areal Flood Warning	RIW	Fremont	47 hr
May 27, 10:24 AM MDT	Special Weather Statement	RIW	Fremont	36 min
May 27, 11:03 AM MDT	Special Weather Statement	RIW	Fremont	42 min
May 27, 11:19 AM MDT	Flash Flood Warning	RIW	Fremont	3 hr
May 27, 11:42 AM MDT	Special Weather Statement	RIW		33 min
May 27, 11:50 AM MDT	Special Weather Statement	RIW		40 min
May 27, 11:58 AM MDT	Special Weather Statement	RIW	Fremont	47 min
May 27, 12:01 PM MDT	Flash Flood Warning	RIW	Fremont	3 hr
May 27, 12:15 PM MDT	Special Weather Statement	RIW		45 min
May 27, 12:18 PM MDT	Tornado Warning	RIW	Fremont	27 min
May 27, 12:39 PM MDT	Special Weather Statement	RIW		51 min
May 27, 12:45 PM MDT	Tornado Warning	RIW	Fremont	30 min
May 27, 12:52 PM MDT	Severe Thunderstorm Warning	RIW	Fremont	38 min
May 27, 12:54 PM MDT	Flash Flood Warning	RIW	Sweetwater	3 hr
May 27, 1:01 PM MDT	Flash Flood Warning	RIW	Fremont	3 hr
May 27, 1:07 PM MDT	Special Weather Statement	RIW	Fremont	38 min
May 27, 1:13 PM MDT	Severe Thunderstorm Warning	RIW	Fremont	62 min
May 27, 1:25 PM MDT	Special Weather Statement	RIW		50 min
May 27, 1:27 PM MDT	Severe Thunderstorm Warning	RIW	Sweetwater	63 min
May 27, 1:38 PM MDT	Tornado Warning	RIW	Sweetwater	37 min
May 27, 2:03 PM MDT	Special Weather Statement	RIW	Fremont	42 min
May 27, 2:12 PM MDT	Special Weather Statement	RIW		33 min
May 27, 2:13 PM MDT	Tornado Warning	RIW	Fremont, Sweetwater	47 min
May 27, 2:14 PM MDT	Special Weather Statement	RIW	Teton	46 min
May 27, 2:24 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	51 min
May 27, 2:52 PM MDT	Special Weather Statement	RIW	Fremont	38 min
May 27, 3:05 PM MDT	Special Weather Statement	RIW		40 min
May 27, 3:13 PM MDT	Special Weather Statement	RIW	Natrona	47 min
May 27, 3:22 PM MDT	Special Weather Statement	RIW	Hot Springs	53 min
May 27, 3:42 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	48 min
May 27, 3:44 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	46 min
May 27, 4:13 PM MDT	Tornado Warning	RIW	Natrona	32 min
May 27, 4:18 PM MDT	Special Weather Statement	RIW	Hot Springs	42 min
May 27, 4:29 PM MDT	Severe Thunderstorm Warning	RIW	Natrona	46 min
May 27, 4:38 PM MDT	Severe Thunderstorm Warning	RIW	Big Horn, Hot Springs, Park, Washakie	37 min
May 27, 4:46 PM MDT	Areal Flood Advisory	RIW	Natrona	119 min
May 27, 5:43 PM MDT	Severe Thunderstorm Warning	RIW	Big Horn, Park	47 min

Nearby

Special Weather Statements in Wyoming, 2018 Every special weather statement in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.