Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 7, NWS Hanford, CA

July 29, 2021Mariposa County, Tuolumne County, California

NWS Hanford, CA issued this flash flood warning at Jul 29, 2021, 3:21 PM PDT for Mariposa County, Tuolumne County, California. It was in force for 84 min. 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 29, 2021, 3:21 PM PDT (22:21 UTC)
Expired
Jul 29, 2021, 4:45 PM PDT
In force
84 min
Issued by
NWS Hanford, CA
Area
Storm-based polygon
Flood severity
None

Counties Mariposa County, CA, Tuolumne County, CA

The radar

The San Joaquin Valley radar (KHNX), 177 km from the middle of the area, began a volume at 22:25 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

Oakland, CA (KOAK), launched 12:00Z, 10.4 hours before the alert went out and 224 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, Oakland, CA at 12:00Z on 2021-07-29Temperature 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 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 12:00Z on 2021-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 square meters per square second.1939Sfc1 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
1504 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
98 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

488 
WGUS56 KHNX 292221
FFWHNX
CAC043-109-292345-
/O.NEW.KHNX.FF.W.0007.210729T2221Z-210729T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Joaquin Valley CA
321 PM PDT Thu Jul 29 2021

The National Weather Service in Hanford CA has issued a

* Flash Flood Warning for...
  Northeastern Mariposa County in central California...
  Southwestern Tuolumne County in northern California...

* Until 445 PM PDT.

* At 319 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between one to one and a half 
  inches of rain have fallen. 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 as well as other 
           drainage and low lying areas.

* Some locations that will experience flooding include...
  White Wolf Campground, Hetch Hetchy, Hetch Hetchy Ranger Station,
  Yosemite Creek Campground and Rancheria Falls Wilderness
  Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding is occurring or is imminent. 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 3796 11953 3783 11952 3781 11972 3785 11979
      3792 11982 3800 11973

FLASH FLOOD...RADAR INDICATED Additional rainfall amounts of one 
quarter to one half inches of rain over the next hour.

$$

CMc
2 follow-up statements
156 
WGUS76 KHNX 292309
FFSHNX

Flash Flood Statement
National Weather Service San Joaquin Valley CA
409 PM PDT Thu Jul 29 2021

CAC043-109-292345-
/O.CON.KHNX.FF.W.0007.000000T0000Z-210729T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mariposa CA-Tuolumne CA-
409 PM PDT Thu Jul 29 2021

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 445 PM PDT FOR
NORTHEASTERN MARIPOSA AND SOUTHWESTERN TUOLUMNE COUNTIES...

At 406 PM PDT, Doppler radar indicated that heavy rainfall across 
the area has ended. Between one to two inches of rain has 
fallen. Flash flooding is ongoing.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar indicated.

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

Some locations that will experience flooding include...
White Wolf Campground, Hetch Hetchy, Hetch Hetchy Ranger Station,
Yosemite Creek Campground and Rancheria Falls Wilderness Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding is occurring or is imminent. 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 3796 11953 3783 11952 3781 11972 3785 11979
      3792 11982 3800 11973

FLASH FLOOD...RADAR INDICATED

$$

CMc
272 
WGUS76 KHNX 292342
FFSHNX

Flash Flood Statement
National Weather Service San Joaquin Valley CA
442 PM PDT Thu Jul 29 2021

CAC043-109-292351-
/O.EXP.KHNX.FF.W.0007.000000T0000Z-210729T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mariposa CA-Tuolumne CA-
442 PM PDT Thu Jul 29 2021

...THE FLASH FLOOD WARNING FOR NORTHEASTERN MARIPOSA AND SOUTHWESTERN
TUOLUMNE COUNTIES WILL EXPIRE AT 445 PM PDT...

The heavy rain has ended. Localized areal flooding is still possible 
in the area for the next hour. Please continue to heed any remaining 
road closures.

LAT...LON 3796 11953 3783 11952 3781 11972 3785 11979
      3792 11982 3800 11973

$$

CMc

The office that day

Everything else NWS Hanford, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 28, 5:07 PM PDTFlash Flood WarningHNXMadera, Mariposa, Tuolumne3 min
Jul 28, 5:23 PM PDTFlash Flood WarningHNXMadera, Mariposa, Tuolumne82 min
Jul 28, 7:00 PM PDTSpecial Weather StatementHNXTulare45 min
Jul 29, 9:38 AM PDTFlash Flood WatchHNX58 hr
Jul 29, 1:51 PM PDTSpecial Weather StatementHNXMariposa39 min
Jul 29, 1:52 PM PDTSpecial Weather StatementHNXMariposa38 min
Jul 29, 2:03 PM PDTFlash Flood WarningHNXMadera, Mariposa117 min
Jul 29, 2:24 PM PDTSpecial Weather StatementHNXTuolumne36 min
Jul 29, 3:07 PM PDTSpecial Weather StatementHNXMariposa38 min
Jul 29, 3:46 PM PDTFlash Flood WarningHNXMariposa119 min
Jul 29, 4:41 PM PDTAreal Flood AdvisoryHNXMariposa, Tuolumne64 min

Nearby

Flash Flood Warnings in California, 2021Every 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.