Alert archive / California / Red Flag Warnings in 2021

Red Flag Warning 13, NWS Reno, NV

August 4, 20219 counties in California; 7 counties in Nevada

NWS Reno, NV issued this red flag warning at Aug 4, 2021, 3:30 AM PDT for 9 counties in California; 7 counties in Nevada. It took effect at Aug 5, 2021, 12:00 AM PDT. It was in force for 22 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
Aug 4, 2021, 3:30 AM PDT (10:30 UTC)
In effect from
Aug 5, 2021, 12:00 AM PDT
Expired
Aug 5, 2021, 9:53 PM PDT
In force
22 hr
Issued by
NWS Reno, NV

Counties El Dorado County, CA, Lassen County, CA, Madera County, CA, Modoc County, CA, Mono County, CA, Nevada County, CA, Placer County, CA, Plumas County, CA, Sierra County, CA, Churchill County, NV, Douglas County, NV, Lyon County, NV, Mineral County, NV, Pershing County, NV, Storey County, NV, Washoe County, NV

The radar

The Reno radar (KRGX), 46 km from the middle of the area, began a volume at 10:29 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

Reno, NV (KREV), launched 00:00Z, 10.5 hours before the alert went out and 137 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-pSkew-T log-p diagram, Reno, NV at 00:00Z on 2021-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 80 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Reno, NV at 00:00Z on 2021-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 2 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
80 J/kg
Mixed-layer CIN
-58 J/kg
Mixed-layer LCL
3976 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
2 m²/s²
0-3 km storm-relative helicity
17 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

007 
WWUS85 KREV 041030
RFWREV

URGENT - FIRE WEATHER MESSAGE
National Weather Service Reno NV
330 AM PDT Wed Aug 4 2021

CAZ271-272-278-052300-
/O.UPG.KREV.FW.A.0012.210805T0700Z-210806T0500Z/
/O.NEW.KREV.FW.W.0013.210805T0700Z-210806T0500Z/
Western Lassen, Eastern Plumas, and Eastern Sierra Counties-
Greater Lake Tahoe and Truckee Area-Eastern Lassen County-
330 AM PDT Wed Aug 4 2021

...RED FLAG WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 10 PM PDT
THURSDAY FOR GUSTY WINDS AND LOW HUMIDITY FOR THE NORTHERN SIERRA,
NORTHEAST CALIFORNIA AND GREATER LAKE TAHOE TRUCKEE AREAS...

The National Weather Service in Reno has issued a Red Flag
Warning for gusty winds and low humidity, which is in effect from
midnight tonight to 10 PM PDT Thursday. The Fire Weather Watch is
no longer in effect.

* CHANGES...Upgrade to Red Flag Warning.

* Affected Area...Fire Zone 271 Western Lassen, Eastern Plumas, 
  and Eastern Sierra Counties, Fire Zone 272 Greater Lake Tahoe 
  and Truckee Area and Fire Zone 278 Eastern Lassen County.

* Winds...Southwest 15 to 20 mph with gusts 30 to 40 mph. Higher 
  gusts likely in wind prone areas and along exposed terrain.

* Humidity...Minimum values of 5 to 15 percent.

* Duration...5 to 8 hours for most areas. Up to 10 hours along 
  exposed midslopes and ridges.

* Impacts...The combination of gusty winds and low humidity can 
  cause fire to rapidly grow in size and intensity before first 
  responders can contain them.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Avoid outdoor activities that can cause a spark near dry
vegetation, such as yard work, target shooting, or campfires.
Follow local fire restrictions. Check weather.gov/reno for
updates and livingwithfire.info for preparedness tips.

&&

$$

CAZ270-274-NVZ420-421-423-429-458-052300-
/O.UPG.KREV.FW.A.0012.210805T1700Z-210806T0500Z/
/O.NEW.KREV.FW.W.0013.210805T1700Z-210806T0500Z/
Surprise Valley California-Southern Mono County-
Northern Sierra Front including Carson City, Douglas, Storey,
Southern Washoe, Western Lyon, and Far Southern Lassen Counties-
Southern Sierra Front including Alpine, Northern Mono, Southern
Lyon, and Western Mineral Counties-
West Humboldt Basin in Pershing County-
Lahontan Basin including Churchill and Eastern Mineral Counties-
Northern Washoe County-
330 AM PDT Wed Aug 4 2021

...RED FLAG WARNING IN EFFECT FROM 10 AM TO 10 PM PDT THURSDAY
FOR GUSTY WINDS AND LOW HUMIDITY FOR THE SIERRA FRONT, WESTERN NEVADA,
AND EASTERN SIERRA...

The National Weather Service in Reno has issued a Red Flag
Warning for gusty winds and low humidity, which is in effect from
10 AM to 10 PM PDT Thursday. The Fire Weather Watch is no longer
in effect.

* Changes...Upgrade to Red Flag Warning.

* Affected Area...Fire Zone 270 Surprise Valley California, Fire 
  Zone 274 Southern Mono County, Fire Zone 420 Northern Sierra 
  Front including Carson City, Douglas, Storey, Southern Washoe, 
  Western Lyon, and Far Southern Lassen Counties, Fire Zone 421 
  Southern Sierra Front including Alpine, Northern Mono, 
  Southern Lyon, and Western Mineral Counties, Fire Zone 423 
  West Humboldt Basin in Pershing County, Fire Zone 429 Lahontan 
  Basin including Churchill and Eastern Mineral Counties and 
  Fire Zone 458 Northern Washoe County.

* Winds...Southwest 15 to 20 mph with gusts 30 to 40 mph. Higher 
  gusts likely in wind prone areas and along exposed terrain.

* Humidity...Minimum values of 5 to 15 percent.

* Duration...6 to 9 hours for most areas. Up to 12 hours along 
  exposed midslopes and ridges.

* Impacts...The combination of gusty winds and low humidity can 
  cause fire to rapidly grow in size and intensity before first 
  responders can contain them.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Avoid outdoor activities that can cause a spark near dry
vegetation, such as yard work, target shooting, or campfires.
Follow local fire restrictions. Check weather.gov/reno for
updates and livingwithfire.info for preparedness tips.

&&

$$

http://weather.gov/reno
1 follow-up statement
084 
WWUS85 KREV 060453
RFWREV

URGENT - FIRE WEATHER MESSAGE
National Weather Service Reno NV
953 PM PDT Thu Aug 5 2021

CAZ270>272-274-278-NVZ420-421-423-429-458-060600-
/O.CAN.KREV.FW.W.0013.000000T0000Z-210806T0500Z/
Surprise Valley California-
Western Lassen, Eastern Plumas, and Eastern Sierra Counties-
Greater Lake Tahoe and Truckee Area-Southern Mono County-
Eastern Lassen County-
Northern Sierra Front including Carson City, Douglas, Storey,
Southern Washoe, Western Lyon, and Far Southern Lassen Counties-
Southern Sierra Front including Alpine, Northern Mono, Southern
Lyon, and Western Mineral Counties-
West Humboldt Basin in Pershing County-
Lahontan Basin including Churchill and Eastern Mineral Counties-
Northern Washoe County-
953 PM PDT Thu Aug 5 2021

...RED FLAG WARNING IS CANCELLED FOR GUSTY WINDS AND LOW HUMIDITY
FOR THE SIERRA FRONT, WESTERN NEVADA, AND EASTERN SIERRA...

The National Weather Service in Reno has cancelled the Red Flag
Warning.

Wind speeds have fallen below critical levels and will continue to
decrease overnight and thus the Red Flag Warning has been
cancelled. However, humidities will remain very dry tonight and 
breezy conditions will continue for several more hours, 
especially at wind prone locations. 

$$

http://weather.gov/reno

The office that day

Everything else NWS Reno, NV issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 4, 3:22 PM PDTLake Wind AdvisoryREVAlpine, El Dorado, Lassen, Mono, Nevada, Placer and 2 more30 hr

Nearby

Red Flag Warnings in California, 2021Red Flag Warnings in Nevada, 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.