Alert archive / Wyoming / Flash Flood Warnings in 2021
Flash Flood Warning 1, NWS Riverton, WY
NWS Riverton, WY issued this flash flood warning at Jul 30, 2021, 4:29 PM MDT for Natrona County, Wyoming. It was in force for 3 hr. 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, 4:29 PM MDT (22:29 UTC)
- Expired
- Jul 30, 2021, 7:30 PM MDT
- In force
- 3 hr
- Issued by
- NWS Riverton, WY
- Area
- Storm-based polygon
- Flood severity
- None
County Natrona County, WY
The radar
The Riverton/Lander radar (KRIW), 101 km from the middle of the area, began a volume at 22:33 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, 10.5 hours before the alert went out and 95 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.
472
WGUS55 KRIW 302229
FFWRIW
WYC025-310130-
/O.NEW.KRIW.FF.W.0001.210730T2229Z-210731T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Riverton WY
429 PM MDT Fri Jul 30 2021
The National Weather Service in Riverton has issued a
* Flash Flood Warning for...
Northwestern Natrona County in central Wyoming...
* Until 730 PM MDT.
* At 429 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 2.5 and 4 inches of
rain have fallen. Flash flooding is ongoing or expected to begin
shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
IMPACT...Flooding of small creeks and streams as well as other
drainage and low lying areas.
* Some locations that will experience flash flooding include...
Arminto.
This includes the following streams and drainages...
Waltman Draw, Cedar Gap Draw, E-K Creek, Dean Springs Draw, Cave
Gulch, Poison Creek, Jackpot Reservoir Draw, South Fork Cottonwood
Creek, Red Creek and Alkali Creek.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Be aware of your surroundings and do not drive on flooded roads.
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 4329 10729 4327 10716 4309 10702 4319 10750
FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR
$$
VandenBoogart2 follow-up statements
555
WGUS75 KRIW 302331
FFSRIW
Flash Flood Statement
National Weather Service Riverton WY
531 PM MDT Fri Jul 30 2021
WYC025-310130-
/O.CON.KRIW.FF.W.0001.000000T0000Z-210731T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Natrona WY-
531 PM MDT Fri Jul 30 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 PM MDT THIS
EVENING FOR NORTHWESTERN NATRONA COUNTY...
At 531 PM MDT, rain has become light in the warned area, with
Doppler radar previously indicating that thunderstorms produced
heavy rain across the warned area. It will take some time for this
water to flow through the affected drainage. Between 2.5 and 4.5
inches of rain have fallen with light rain currently continuing.
Flash flooding is likely ongoing, and more heavy rain is possible
later this evening.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
IMPACT...Flooding of small creeks and streams as well as other
drainage and low lying areas.
Some locations that will experience flash flooding include...
Arminto.
This includes the following streams and drainages...
Waltman Draw, Cedar Gap Draw, E-K Creek, Dean Springs Draw, Cave
Gulch, Poison Creek, Jackpot Reservoir Draw, South Fork Cottonwood
Creek, Red Creek and Alkali Creek.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Be aware of your surroundings and do not drive on flooded roads.
In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.
&&
LAT...LON 4329 10729 4327 10716 4309 10702 4319 10750
FLASH FLOOD...RADAR INDICATED
$$
VandenBoogart371 WGUS75 KRIW 310127 FFSRIW Flash Flood Statement National Weather Service Riverton WY 727 PM MDT Fri Jul 30 2021 WYC025-310137- /O.EXP.KRIW.FF.W.0001.000000T0000Z-210731T0130Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Natrona WY- 727 PM MDT Fri Jul 30 2021 ...FLASH FLOOD WARNING WILL EXPIRE AT 730 PM MDT THIS EVENING FOR NORTHWESTERN NATRONA COUNTY... Flood waters have receded. Flooding is no longer expected to pose a threat. Rural roads could remain washed out. Please be careful when driving. LAT...LON 4329 10729 4327 10716 4309 10702 4319 10750 $$ Murrell
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, 4:42 PM MDT | Special Weather Statement | RIW | Natrona | 33 min |
| Jul 30, 4:56 PM MDT | Special Weather Statement | RIW | Big Horn | 34 min |
| Jul 30, 4:57 PM MDT | Areal Flood Advisory | RIW | Lincoln | 107 min |
Nearby
Flash Flood Warnings in Wyoming, 2021Every flash flood warning 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.