Alert archive / California / Flash Flood Watches in 2021

Flash Flood Watch 3, NWS Reno, NV

October 20, 2021Lassen County, Plumas County, Sierra County, California

NWS Reno, NV issued this flash flood watch at Oct 20, 2021, 11:30 AM PDT for Lassen County, Plumas County, Sierra County, California. It took effect at Oct 21, 2021, 11:00 PM PDT. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued
Oct 20, 2021, 11:30 AM PDT (18:30 UTC)
In effect from
Oct 21, 2021, 11:00 PM PDT
Expired
Oct 22, 2021, 11:00 AM PDT
In force
12 hr
Issued by
NWS Reno, NV
Flood severity
None

Counties Lassen County, CA, Plumas County, CA, Sierra County, CA

The radar

The Beale AFB radar (KBBX), 107 km from the middle of the area, began a volume at 18:34 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 12:00Z, 6.5 hours before the alert went out and 217 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 12:00Z on 2021-10-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Reno, NV at 12:00Z on 2021-10-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 203 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2270 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
203 m²/s²
0-3 km storm-relative helicity
365 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

199 
WGUS65 KREV 201830
FFAREV

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Reno NV
1130 AM PDT Wed Oct 20 2021

CAZ071-221800-
/O.NEW.KREV.FF.A.0003.211022T0600Z-211022T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lassen-Eastern Plumas-Eastern Sierra Counties-
Including the cities of Sierraville, Westwood, Susanville, Loyalton, 
and Portola
1130 AM PDT Wed Oct 20 2021

...FLASH FLOOD AND DEBRIS FLOW WATCH IN EFFECT FROM THURSDAY EVENING 
THROUGH FRIDAY MORNING...

The National Weather Service in Reno has issued a

* Flash Flood Watch for a portion of northeast California, including 
  the following area, Lassen-Eastern Plumas-Eastern Sierra Counties.

* From Thursday evening through Friday morning.

* A short period of heavy rainfall is possible Thursday night and 
  Friday morning in and downstream of the Dixie, Sheep, Walker, and 
  Beckwourth burn scars.

* Debris flows, ash flows, rock falls, and tree falls are possible 
  with short bursts of heavy rainfall.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

BB
2 follow-up statements
208 
WGUS65 KREV 212138
FFAREV

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Reno NV
238 PM PDT Thu Oct 21 2021

CAZ071-222145-
/O.NEW.KREV.FA.A.0001.211024T0600Z-211025T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
/O.CON.KREV.FF.A.0003.211022T0600Z-211022T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lassen-Eastern Plumas-Eastern Sierra Counties-
Including the cities of Sierraville, Westwood, Susanville, Loyalton, 
and Portola
238 PM PDT Thu Oct 21 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 11 PM PDT THIS EVENING 
THROUGH FRIDAY MORNING...
...FLOOD WATCH IN EFFECT FROM SATURDAY EVENING THROUGH LATE SUNDAY 
NIGHT...

The Flash Flood Watch continues for

* A portion of northeast California, including the following area, 
  Lassen-Eastern Plumas-Eastern Sierra Counties.

* From 11 PM PDT this evening through Friday morning.

* A short period of heavy rainfall is possible Thursday night and 
  Friday morning in and downstream of the Dixie, Sheep, Walker, and 
  Beckwourth burn scars.

* Debris flows, ash flows, rock falls, and tree falls are possible 
  with short bursts of heavy rainfall.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

The National Weather Service in Reno has issued a

* Flood Watch for a portion of northeast California, including the 
  following area, Lassen-Eastern Plumas-Eastern Sierra Counties.

* From Saturday evening through late Sunday night.

* Additional heavy rainfall from an atmospheric river will move into 
  the region Saturday and continue into Sunday night. High snow 
  levels will lower below 6000 feet by Monday morning.

* Debris flows, ash flows, rock falls, and tree falls are possible, 
  especially on or near burn scars and steep terrain. Rises on small 
  creeks and streams are expected, equipment in and near river and 
  creek channels should be moved to safety. Rock falls in canyons 
  and ponding of water on roads will create hazardous driving 
  conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

CAZ072-NVZ002-003-222145-
/O.NEW.KREV.FA.A.0001.211024T1200Z-211025T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Greater Lake Tahoe Area-Greater Lake Tahoe Area-Greater Reno-Carson
City-Minden Area-
Including the cities of Truckee, Virginia City, Stateline, Tahoe 
City, Sparks, Glenbrook, Incline Village, Gardnerville, South Lake 
Tahoe, Markleeville, and Verdi
238 PM PDT Thu Oct 21 2021

...FLOOD WATCH IN EFFECT FROM LATE SATURDAY NIGHT THROUGH MONDAY 
MORNING...

The National Weather Service in Reno has issued a

* Flood Watch for portions of east central California and western 
  Nevada, including the following areas, in east central California, 
  Greater Lake Tahoe Area. In western Nevada, Greater Lake Tahoe 
  Area and Greater Reno-Carson City-Minden Area.

* From late Saturday night through Monday morning.

* Heavy rainfall from an atmospheric river will move into the region 
  Saturday night and may continue into Monday morning. High snow 
  levels will lower to near 6000 feet sometime Monday.

* Debris flows, ash flows, rock falls, and tree falls are possible, 
  especially on or near burn scars and steep terrain. This includes 
  the Tamarack, Caldor, and Numbers burn scars. Rises on small 
  creeks and streams are expected, equipment in and near river and 
  creek channels should be moved to safety. Rock falls in canyons 
  and ponding of water on roads will create hazardous driving 
  conditions, especially along Interstate 80 between Truckee and 
  Reno. Localized urban flooding is also possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings.

&&

$$

CAZ073-222145-
/O.NEW.KREV.FA.A.0001.211024T1800Z-211026T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mono County-
Including the cities of Bridgeport, Lee Vining, Coleville, and 
Mammoth Lakes
238 PM PDT Thu Oct 21 2021

...FLOOD WATCH IN EFFECT FROM SUNDAY MORNING THROUGH MONDAY 
AFTERNOON...

The National Weather Service in Reno has issued a

* Flood Watch for a portion of east central California, including 
  the following area, Mono County.

* From Sunday morning through Monday afternoon.

* Heavy rainfall from an atmospheric river will move into the 
  eastern Sierra by Sunday morning and may continue into Monday 
  afternoon. High snow levels will lower to near 7000 feet sometime 
  Monday.

* Debris flows, ash flows, rock falls, and tree falls are possible, 
  especially on or near burn scars and steep terrain. This includes 
  the Slink and Boot burn scars. Rises on small creeks and streams 
  are expected, equipment in and near river and creek channels 
  should be moved to safety.  Rock falls in canyons and ponding of 
  water on roads will create hazardous driving conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings.

&&

$$

BB
617 
WGUS65 KREV 221756
FFAREV

Flood Watch
National Weather Service Reno NV
1056 AM PDT Fri Oct 22 2021

.The heaviest rain is moving out of the area this morning with the 
next system still on track to move into the region Saturday evening.

CAZ071-230200-
/O.EXP.KREV.FF.A.0003.000000T0000Z-211022T1800Z/
/O.CON.KREV.FA.A.0001.211024T0600Z-211025T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lassen-Eastern Plumas-Eastern Sierra Counties-
Including the cities of Sierraville, Westwood, Susanville, Loyalton, 
and Portola
1056 AM PDT Fri Oct 22 2021

...FLOOD WATCH REMAINS IN EFFECT FROM SATURDAY EVENING THROUGH LATE 
SUNDAY NIGHT...
...FLASH FLOOD WATCH WILL EXPIRE AT 11 AM PDT THIS MORNING...

The Flood Watch continues for

* A portion of northeast California, including the following area, 
  Lassen-Eastern Plumas-Eastern Sierra Counties.

* From Saturday evening through late Sunday night.

* Additional heavy rainfall from an atmospheric river will move into 
  the region Saturday and continue into Sunday night. High snow 
  levels will lower below 6000 feet by Monday morning.

* Debris flows, ash flows, rock falls, and tree falls are possible, 
  especially on or near burn scars and steep terrain. Rises on small 
  creeks and streams are expected, equipment in and near river and 
  creek channels should be moved to safety. Rock falls in canyons 
  and ponding of water on roads will create hazardous driving 
  conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

The Flash Flood Watch for a portion of northeast California, 
including the following area, Lassen-Eastern Plumas-Eastern Sierra 
Counties will expire at 11 AM PDT this morning.

Please continue to heed remaining road closures.

$$

CAZ072-NVZ002-003-230200-
/O.CON.KREV.FA.A.0001.211024T1200Z-211025T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Greater Lake Tahoe Area-Greater Lake Tahoe Area-Greater Reno-Carson
City-Minden Area-
Including the cities of Truckee, Virginia City, Stateline, Tahoe 
City, Sparks, Glenbrook, Incline Village, Gardnerville, South Lake 
Tahoe, Markleeville, and Verdi
1056 AM PDT Fri Oct 22 2021

...FLOOD WATCH REMAINS IN EFFECT FROM LATE SATURDAY NIGHT THROUGH 
MONDAY MORNING...

The Flood Watch continues for

* Portions of east central California and western Nevada, including 
  the following areas, in east central California, Greater Lake 
  Tahoe Area. In western Nevada, Greater Lake Tahoe Area and Greater 
  Reno-Carson City-Minden Area.

* From late Saturday night through Monday morning.

* Heavy rainfall from an atmospheric river will move into the region 
  Saturday night and may continue into Monday morning. High snow 
  levels will lower to near 6000 feet sometime Monday.

* Debris flows, ash flows, rock falls, and tree falls are possible, 
  especially on or near burn scars and steep terrain. This includes 
  the Tamarack, Caldor, and Numbers burn scars. Rises on small 
  creeks and streams are expected, equipment in and near river and 
  creek channels should be moved to safety. Rock falls in canyons 
  and ponding of water on roads will create hazardous driving 
  conditions, especially along Interstate 80 between Truckee and 
  Reno. Localized urban flooding is also possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

CAZ073-230200-
/O.CON.KREV.FA.A.0001.211024T1800Z-211026T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mono County-
Including the cities of Bridgeport, Lee Vining, Coleville, and 
Mammoth Lakes
1056 AM PDT Fri Oct 22 2021

...FLOOD WATCH REMAINS IN EFFECT FROM SUNDAY MORNING THROUGH MONDAY 
AFTERNOON...

The Flood Watch continues for

* A portion of east central California, including the following 
  area, Mono County.

* From Sunday morning through Monday afternoon.

* Heavy rainfall from an atmospheric river will move into the 
  eastern Sierra by Sunday morning and may continue into Monday 
  afternoon. High snow levels will lower to near 7000 feet sometime 
  Monday.

* Debris flows, ash flows, rock falls, and tree falls are possible, 
  especially on or near burn scars and steep terrain. This includes 
  the Slink and Boot burn scars. Rises on small creeks and streams 
  are expected, equipment in and near river and creek channels 
  should be moved to safety.  Rock falls in canyons and ponding of 
  water on roads will create hazardous driving conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

DJ

Nearby

Flash Flood Watches in California, 2021Every flash flood watch 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.