Alert archive / Wyoming / Special Weather Statements in 2021
Special Weather Statement, NWS Riverton, WY
NWS Riverton, WY issued this special weather statement at Jul 30, 2021, 4:56 PM MDT for Big Horn County, Wyoming. It was in force for 34 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
- Jul 30, 2021, 4:56 PM MDT (22:56 UTC)
- Expired
- Jul 30, 2021, 5:30 PM MDT
- In force
- 34 min
- Issued by
- NWS Riverton, WY
County Big Horn County, WY
The radar
The Riverton/Lander radar (KRIW), 159 km from the middle of the area, began a volume at 22:58 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, 10.9 hours before the alert went out and 156 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.
- Mixed-layer CAPE
- 6 J/kg
- Mixed-layer CIN
- -247 J/kg
- Mixed-layer LCL
- 1343 m above ground
- 0-6 km bulk shear
- 6 kt
- 0-1 km storm-relative helicity
- -22 m²/s²
- 0-3 km storm-relative helicity
- 98 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
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</html>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 Jul 30, 11:51 AM MDT, 5 hours 5 minutes earlier.
Area forecast discussion, Jul 30, 11:51 AM MDT, 5 hours 5 minutes before
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<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Service Notice</title>
<link rel="stylesheet" href="index.css">
</head>
<body>
<main class="wrap">
<section class="card" role="status" aria-live="polite">
<div class="status" id="status">Temporary Notice</div>
<h1 id="headline">This service is currently unavailable.</h1>
<p id="message1">
The site you requested is temporarily down for maintenance or an unexpected outage.
</p>
<p id="message2">
Please try again in a few minutes.
</p>
<p class="small" id="detail">
If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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</html>Hazardous weather outlook, Jul 30, 2:58 PM MDT, 1 hour 58 minutes before
Hazardous Weather Outlook National Weather Service Riverton WY 258 PM MDT Fri Jul 30 2021 WYZ001>020-022>030-312100- 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- 258 PM MDT Fri Jul 30 2021 This Hazardous Weather Outlook is for Western and Central Wyoming. .DAY ONE...This Afternoon and Tonight. Numerous thunderstorms are likely this afternoon and evening, especially west of the Divide. Some thunderstorms may produce locally heavy rainfall, and a Flash Flood Watch covers the area with the highest potential to see localized flash flood. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Showers and thunderstorms are likely Saturday through Monday. The main hazard will be locally heavy rainfall which could cause localized flash flooding. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
In the hours before
Local storm report, Jul 30, 2:27 PM MDT, 2 hours 29 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
227 PM MDT FRI JUL 30 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0220 PM HEAVY RAIN ATLANTIC CITY 42.50N 108.73W
07/30/2021 M0.51 INCH FREMONT WY CO-OP OBSERVER
ABOUT HALF AN INCH OF RAIN IN ROUGHLY 15
MINUTES. NO FLOOD ISSUES SEEN. CELL MOVED
THROUGH QUICKLY.
&&
LVSpecial weather statement, Jul 30, 3:01 PM MDT, 1 hour 55 minutes before
Special Weather Statement
National Weather Service Riverton WY
301 PM MDT Fri Jul 30 2021
WYZ019-302130-
Green Mountains and Rattlesnake Range-
301 PM MDT Fri Jul 30 2021
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN NATRONA COUNTY UNTIL
330 PM MDT...
At 300 PM MDT, Doppler radar was tracking a strong thunderstorm near
Split Rock, or 18 miles east of Jeffrey City, moving east at 10 mph.
Half inch hail and winds in excess of 30 mph will be possible with
this storm.
This storm will remain over mainly rural areas of southwestern
Natrona County.
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 4244 10746 4243 10753 4257 10754 4266 10724
4243 10719
TIME...MOT...LOC 2100Z 259DEG 11KT 4250 10746
21Special weather statement, Jul 30, 3:32 PM MDT, 1 hour 24 minutes before
Special Weather Statement National Weather Service Riverton WY 332 PM MDT Fri Jul 30 2021 WYZ019-302200- Green Mountains and Rattlesnake Range- 332 PM MDT Fri Jul 30 2021 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN NATRONA COUNTY UNTIL 400 PM MDT... At 330 PM MDT, Doppler radar was tracking a strong thunderstorm near Devil's Gate, or 26 miles east of Jeffrey City, moving east at 20 mph. Half inch hail and winds in excess of 30 mph will be possible with this storm. This strong thunderstorm will be near... Morman Handcart Visitor Center around 345 PM MDT. Independence Rock around 355 PM MDT. 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 4244 10740 4253 10740 4256 10706 4243 10705 TIME...MOT...LOC 2130Z 271DEG 18KT 4244 10730 21
Special weather statement, Jul 30, 4:11 PM MDT, 45 minutes before
Special Weather Statement National Weather Service Riverton WY 411 PM MDT Fri Jul 30 2021 WYZ020-302245- Natrona County Lower Elevations- 411 PM MDT Fri Jul 30 2021 ...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL NATRONA COUNTY UNTIL 445 PM MDT... At 409 PM MDT, Doppler radar was tracking a strong thunderstorm over Waltman Rest Area, or 42 miles east of Shoshoni. This storm was nearly stationary. Torrential Rainfall is occurring between Hiland and Waltman including the Waltman Rest area. Also half inch hail and winds in excess of 30 mph will be possible with this storm. Significant ponding of water is expected along Highway 26. Please slow down to reduce the risk of hydroplaning. 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 4303 10740 4317 10739 4313 10720 4302 10714 TIME...MOT...LOC 2209Z 270DEG 4KT 4308 10729 21
Special weather statement, Jul 30, 4:42 PM MDT, 14 minutes before
Special Weather Statement National Weather Service Riverton WY 442 PM MDT Fri Jul 30 2021 WYZ020-302315- Natrona County Lower Elevations- 442 PM MDT Fri Jul 30 2021 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL NATRONA COUNTY UNTIL 515 PM MDT... At 440 PM MDT, Doppler radar was tracking a strong thunderstorm 7 miles northeast of Powder River, or 34 miles northwest of Casper, moving east at 10 mph. Penny size hail and winds in excess of 30 mph will be possible with this storm. This strong thunderstorm will be near... Goldeneye Reservoir around 515 PM MDT. Natrona around 525 PM MDT. Other locations impacted by this storm include Natrona. 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 4306 10701 4321 10695 4315 10664 4293 10671 TIME...MOT...LOC 2240Z 284DEG 9KT 4311 10689 21
Special weather statement, Jul 30, 4:56 PM MDT, 0 minutes before
Special Weather Statement National Weather Service Riverton WY 456 PM MDT Fri Jul 30 2021 WYZ004-008-302330- North Big Horn Basin-Bighorn Mountains West- 456 PM MDT Fri Jul 30 2021 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN BIG HORN COUNTY UNTIL 530 PM MDT... At 456 PM MDT, Doppler radar was tracking a strong thunderstorm 8 miles northwest of Medicine Lodge Archaeological Site, or 17 miles east of Basin, moving south at 5 mph. Half inch hail and winds in excess of 30 mph will be possible with this storm. This storm will remain over mainly rural areas of southeastern Big Horn County. 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 4446 10777 4441 10752 4427 10757 4431 10788 TIME...MOT...LOC 2256Z 019DEG 6KT 4437 10769 21
The office that day
Everything else NWS Riverton, WY issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 29, 6:29 PM MDT | Special Weather Statement | RIW | Johnson | 31 min |
| Jul 29, 6:48 PM MDT | Special Weather Statement | RIW | Teton | 42 min |
| Jul 29, 6:55 PM MDT | Special Weather Statement | RIW | Natrona | 35 min |
| Jul 29, 6:58 PM MDT | Special Weather Statement | RIW | Johnson | 32 min |
| Jul 29, 7:33 PM MDT | Special Weather Statement | RIW | 27 min | |
| Jul 29, 7:35 PM MDT | Special Weather Statement | RIW | Johnson | 25 min |
| Jul 29, 7:54 PM MDT | Special Weather Statement | RIW | Natrona | 36 min |
| Jul 29, 8:00 PM MDT | Special Weather Statement | RIW | Johnson | 30 min |
| Jul 29, 8:06 PM MDT | Areal Flood Advisory | RIW | Johnson | 3 hr |
| Jul 29, 8:37 PM MDT | Special Weather Statement | RIW | 38 min | |
| Jul 29, 10:10 PM MDT | Special Weather Statement | RIW | 35 min | |
| Jul 29, 10:24 PM MDT | Special Weather Statement | RIW | Natrona | 36 min |
| Jul 29, 10:37 PM MDT | Special Weather Statement | RIW | Natrona | 23 min |
| Jul 30, 12:29 AM MDT | Special Weather Statement | RIW | Natrona | 31 min |
| Jul 30, 1:02 AM MDT | Special Weather Statement | RIW | Natrona | 28 min |
| Jul 30, 1:19 AM MDT | Areal Flood Advisory | RIW | Natrona | 3 hr |
| Jul 30, 1:38 AM MDT | Special Weather Statement | RIW | Natrona | 37 min |
| Jul 30, 2:58 AM MDT | Flash Flood Watch | RIW | Fremont, Lincoln, Natrona, Sublette, Sweetwater, Teton | 41 hr |
| Jul 30, 2:16 PM MDT | Areal Flood Advisory | RIW | Fremont | 119 min |
| Jul 30, 3:01 PM MDT | Special Weather Statement | RIW | 29 min | |
| Jul 30, 3:28 PM MDT | Areal Flood Advisory | RIW | Natrona | 61 min |
| Jul 30, 3:32 PM MDT | Special Weather Statement | RIW | 28 min | |
| Jul 30, 3:38 PM MDT | Areal Flood Advisory | RIW | Fremont | 2 hr |
| Jul 30, 4:11 PM MDT | Special Weather Statement | RIW | Natrona | 34 min |
| Jul 30, 4:29 PM MDT | Flash Flood Warning | RIW | Natrona | 3 hr |
| Jul 30, 4:42 PM MDT | Special Weather Statement | RIW | Natrona | 33 min |
| Jul 30, 4:57 PM MDT | Areal Flood Advisory | RIW | Lincoln | 107 min |
Nearby
Special Weather Statements in Wyoming, 2021Every special weather statement in 2021
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.