Alert archive / California / Flash Flood Warnings in 2020

Flash Flood Warning 13, NWS Reno, NV

July 22, 2020Sierra County, California

NWS Reno, NV issued this flash flood warning at Jul 22, 2020, 2:56 PM PDT for Sierra County, California. 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 22, 2020, 2:56 PM PDT (21:56 UTC)
Expired: Jul 22, 2020, 6:00 PM PDT
In force: 3 hr
Issued by: NWS Reno, NV
Area: Storm-based polygon
Flood severity: None

County Sierra County, CA

The radar

The Reno radar (KRGX), 66 km from the middle of the area, began a volume at 21:58 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

Reno, NV (KREV), launched 12:00Z, 9.9 hours before the alert went out and 171 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 12 J/kg
Mixed-layer CIN: -360 J/kg
Mixed-layer LCL: 2655 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 9 m²/s²
0-3 km storm-relative helicity: 36 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

301 
WGUS55 KREV 222156
FFWREV
CAC091-230100-
/O.NEW.KREV.FF.W.0013.200722T2156Z-200723T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Reno NV
256 PM PDT Wed Jul 22 2020

The National Weather Service in Reno has issued a

* Flash Flood Warning for...
  Sierra County in northern California...

* Until 600 PM PDT.

* At 254 PM PDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Flash flooding is ongoing or
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar indicated.

  IMPACT...Flooding of small creeks and streams, streets, as well as 
           other drainage and low lying areas.

* Some locations that will experience flooding include...
  Stampede Reservoir, Dog Valley, Loyalton, and the Palen Reservoir 
  area. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Flooding is occurring or is imminent. 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. It is important to know where you are relative to streams, 
rivers, or creeks which can become killers in heavy rains. Campers 
and hikers should avoid streams or creeks.

&&

LAT...LON 3968 12024 3956 12003 3950 12003 3947 12013
      3954 12019 3955 12025 3960 12031 3967 12034

FLASH FLOOD...RADAR INDICATED

$$

MB

1 follow-up statement

405 
WGUS75 KREV 230053
FFSREV

Flash Flood Statement
National Weather Service Reno NV
553 PM PDT Wed Jul 22 2020

CAC091-230101-
/O.EXP.KREV.FF.W.0013.000000T0000Z-200723T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sierra CA-
553 PM PDT Wed Jul 22 2020

...THE FLASH FLOOD WARNING FOR SIERRA COUNTY WILL EXPIRE AT 600 PM
PDT...

The heavy rain has ended. While no rain is currently falling, water 
may continue to drain out of terrain over the next few hours. Any 
standing water or ponding will be difficult to see after sunset. 
Travelers should exercise extra caution in the Sierraville and 
Loyalton area. Please continue to heed any remaining road closures.

LAT...LON 3968 12024 3956 12003 3950 12003 3947 12013
      3954 12019 3955 12025 3960 12031 3967 12034

$$

MB

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 21, 6:09 PM PDT	Areal Flood Advisory	REV	Lassen	2 hr
Jul 22, 12:59 PM PDT	Special Weather Statement	REV	Lassen, Plumas	3 hr
Jul 22, 2:08 PM PDT	Severe Thunderstorm Warning	REV	Lassen	37 min
Jul 22, 2:29 PM PDT	Areal Flood Advisory	REV	Plumas	2 hr
Jul 22, 2:44 PM PDT	Severe Thunderstorm Warning	REV	Plumas	31 min
Jul 22, 2:55 PM PDT	Severe Thunderstorm Warning	REV	Alpine	35 min
Jul 22, 3:14 PM PDT	Flash Flood Warning	REV	Plumas	3 hr
Jul 22, 3:24 PM PDT	Flash Flood Warning	REV	Lassen	3 hr
Jul 22, 3:44 PM PDT	Severe Thunderstorm Warning	REV	Sierra	46 min
Jul 22, 3:50 PM PDT	Areal Flood Advisory	REV	Nevada, Sierra	3 hr
Jul 22, 3:58 PM PDT	Severe Thunderstorm Warning	REV	Nevada, Placer	32 min
Jul 22, 4:01 PM PDT	Severe Thunderstorm Warning	REV	Sierra	29 min
Jul 22, 4:31 PM PDT	Flash Flood Warning	REV	Nevada, Placer	116 min

Nearby

Flash Flood Warnings in California, 2020 Every flash flood warning in 2020

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.