Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 3, NWS Reno, NV

July 30, 2021Mono County, California

NWS Reno, NV issued this flash flood warning at Jul 30, 2021, 4:45 PM PDT for Mono 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 30, 2021, 4:45 PM PDT (23:45 UTC)
Expired: Jul 30, 2021, 7:15 PM PDT
In force: 3 hr
Issued by: NWS Reno, NV
Area: Storm-based polygon
Flood severity: None

County Mono County, CA

The radar

The Reno radar (KRGX), 151 km from the middle of the area, began a volume at 23:47 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, 11.8 hours before the alert went out and 170 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2579 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: -6 m²/s²
0-3 km storm-relative helicity: 93 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

347 
WGUS55 KREV 302345
FFWREV
CAC051-310115-
/O.NEW.KREV.FF.W.0003.210730T2345Z-210731T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Reno NV
445 PM PDT Fri Jul 30 2021

The National Weather Service in Reno has issued a

* Flash Flood Warning for...
  Northern Mono County in northern California...

* Until 615 PM PDT.

* At 445 PM PDT, Radar indicated reported thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Boot Fire and potentially across Highway 395. The 
debris flow can consist of rock, mud, vegetation and other loose 
materials.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Trained spotters reported.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Bootleg Campground and Junction U.S 395 And CA 108 (Sonora 
  Junction).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads, and normally dry stream beds is likely. The heavy 
rains will likely trigger rockslides, mudslides and debris flows in 
steep terrain, especially in and around these areas.

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3840 11949 3842 11947 3845 11946 3843 11943
      3841 11942 3839 11937 3837 11941 3835 11942
      3834 11945 3835 11947 3838 11948 3839 11950
      3841 11949

FLASH FLOOD...OBSERVED

$$

EW

2 follow-up statements

249 
WGUS55 KREV 310104
FFWREV
CAC051-310215-
/O.EXT.KREV.FF.W.0003.000000T0000Z-210731T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Reno NV
604 PM PDT Fri Jul 30 2021

The National Weather Service in Reno has extended the

* Flash Flood Warning for...
  Northern Mono County in northern California...

* Until 715 PM PDT.

* At 604 PM PDT, local law enforcement reported thunderstorms 
  producing heavy rain across the warned area. Flash flooding is 
  ongoing or expected to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Boot Fire. The debris flow can consist of rock, 
mud, vegetation and other loose materials.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Law enforcement reported water and mud across the road
           at Highway 395 and State Route 108.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Bootleg Campground and Junction U.S 395 And CA 108 (Sonora 
  Junction).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads, and normally dry stream beds is likely. The heavy 
rains will likely trigger rockslides, mudslides and debris flows in 
steep terrain, especially in and around these areas.

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3840 11949 3842 11947 3845 11946 3843 11943
      3841 11942 3839 11937 3837 11941 3835 11942
      3834 11945 3835 11947 3838 11948 3839 11950
      3841 11949

FLASH FLOOD...OBSERVED

$$

EW

606 
WGUS75 KREV 310212
FFSREV

Flash Flood Statement
National Weather Service Reno NV
712 PM PDT Fri Jul 30 2021

CAC051-310222-
/O.EXP.KREV.FF.W.0003.000000T0000Z-210731T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mono CA-
712 PM PDT Fri Jul 30 2021

...FLASH FLOOD WARNING FOR THE BOOT FIRE BURN SCAR WILL EXPIRE AT 
715 PM PDT THIS EVENING FOR NORTHERN MONO COUNTY...

The heavy rain has ended. However, minor debris flows may be 
ongoing. It is best to stay away from the Boot fire burn scar. 
Any additional rainfall this evening could cause further issues for 
the burn area. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 800 PM PDT Saturday for 
portions of east central California and western Nevada.

LAT...LON 3840 11949 3842 11947 3845 11946 3843 11943
      3841 11942 3839 11937 3837 11941 3835 11942
      3834 11945 3835 11947 3838 11948 3839 11950
      3841 11949

$$

EW

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 29, 5:14 PM PDT	Special Weather Statement	REV	Sierra	61 min
Jul 29, 6:48 PM PDT	Areal Flood Advisory	REV	Plumas	3 hr
Jul 30, 1:10 PM PDT	Special Weather Statement	REV	Alpine, Lassen, Mono, Plumas, Sierra	80 min
Jul 30, 1:40 PM PDT	Special Weather Statement	REV	Sierra	50 min
Jul 30, 3:35 PM PDT	Areal Flood Advisory	REV	Mono	115 min

Nearby

Flash Flood Warnings in California, 2021 Every 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.