Alert archive / Wyoming / Red Flag Warnings in 2021
Red Flag Warning 27, NWS Riverton, WY
NWS Riverton, WY issued this red flag warning at Nov 18, 2021, 2:44 AM MST for Johnson County, Natrona County, Wyoming. It took effect at Nov 18, 2021, 11:00 AM MST. It was in force for 6 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Nov 18, 2021, 2:44 AM MST (09:44 UTC)
- In effect from
- Nov 18, 2021, 11:00 AM MST
- Expired
- Nov 18, 2021, 5:00 PM MST
- In force
- 6 hr
- Issued by
- NWS Riverton, WY
Counties Johnson County, WY, Natrona County, WY
The radar
The Riverton/Lander radar (KRIW), 152 km from the middle of the area, began a volume at 09:42 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 00:00Z, 9.7 hours before the alert went out and 146 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2935 m above ground
- 0-6 km bulk shear
- 65 kt
- 0-1 km storm-relative helicity
- 71 m²/s²
- 0-3 km storm-relative helicity
- 233 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
549 WWUS85 KRIW 180944 RFWRIW URGENT - FIRE WEATHER MESSAGE National Weather Service Riverton WY 244 AM MST Thu Nov 18 2021 WYZ280-190000- /O.UPG.KRIW.FW.A.0017.211118T1800Z-211119T0000Z/ /O.NEW.KRIW.FW.W.0027.211118T1800Z-211119T0000Z/ Natrona County/Casper BLM- 244 AM MST Thu Nov 18 2021 ...RED FLAG WARNING IN EFFECT FROM 11 AM THIS MORNING TO 5 PM MST THIS AFTERNOON... The National Weather Service in Riverton has issued a Red Flag Warning, which is in effect from 11 AM this morning to 5 PM MST this afternoon. the Fire Weather Watch is no longer in effect. * IMPACTS: Low Humidities and Strong Gusty Winds will create erratic fire behavior with any new fire starts. * AFFECTED AREA: In Central WY...Fire Weather Zone 280. * COUNTIES AFFECTED: In Central WY...Natrona. * WIND: Southwest 15 to 25 mph with gusts up to 40 mph. * HUMIDITY: As low as 11 percent. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...and low relative humidity can contribute to extreme fire behavior. && $$ WYZ281-190000- /O.NEW.KRIW.FW.W.0027.211118T1800Z-211119T0000Z/ Johnson County/Casper BLM- 244 AM MST Thu Nov 18 2021 ...RED FLAG WARNING IN EFFECT FROM 11 AM THIS MORNING TO 5 PM MST THIS AFTERNOON... The National Weather Service in Riverton has issued a Red Flag Warning, which is in effect from 11 AM this morning to 5 PM MST this afternoon. * IMPACTS: Low Humidities and Strong Gusty Winds will create erratic fire behavior with any new fire starts. * AFFECTED AREA: In North Central WY...Southern third of Fire Weather Zone 281. * COUNTIES AFFECTED: In North Central WY...Southern third of Johnson. * WIND: Southwest 10 to 20 mph with gusts up to 30 mph. * HUMIDITY: As low as 13 percent. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now....or will shortly. A combination of strong winds...and low relative humidity can contribute to extreme fire behavior. && $$ 21
1 follow-up statement
386 WWUS85 KRIW 182358 RFWRIW URGENT - FIRE WEATHER MESSAGE National Weather Service Riverton WY 458 PM MST Thu Nov 18 2021 WYZ280-281-190100- /O.EXP.KRIW.FW.W.0027.000000T0000Z-211119T0000Z/ Natrona County/Casper BLM-Johnson County/Casper BLM- 458 PM MST Thu Nov 18 2021 ...RED FLAG WARNING WILL EXPIRE AT 5 PM MST THIS AFTERNOON... Relative humidity will increase and winds will slacken somewhat Thursday evening. Therefore, the Red Flag Warning will be allowed to expire. $$ http://weather.gov/riverton
The office that day
Everything else NWS Riverton, WY issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 18, 2:14 PM MST | Winter Weather Advisory | RIW | Fremont, Lincoln, Sublette, Teton | 36 hr |
Nearby
Red Flag Warnings in Wyoming, 2021Every red flag 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.