Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 8, NWS Hanford, CA

July 29, 2021Mariposa County, California

NWS Hanford, CA issued this flash flood warning at Jul 29, 2021, 3:46 PM PDT for Mariposa County, California. It was in force for 119 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, 3:46 PM PDT (22:46 UTC)
Expired
Jul 29, 2021, 5:45 PM PDT
In force
119 min
Issued by
NWS Hanford, CA
Area
Storm-based polygon
Flood severity
None

County Mariposa County, CA

The radar

The San Joaquin Valley radar (KHNX), 154 km from the middle of the area, began a volume at 22:48 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, 10.8 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°0°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.

156 
WGUS56 KHNX 292246
FFWHNX
CAC043-300045-
/O.NEW.KHNX.FF.W.0008.210729T2246Z-210730T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Hanford CA has issued a

* Flash Flood Warning for...
  North central Mariposa County in central California...

* Until 545 PM PDT.

* At 344 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, highways, streets 
           as well as other drainage and low lying areas.

* Some locations that will experience flooding include...
  Yosemite National, Bridalveil Creek Campground and Badger Pass 
  Ranger Station.

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 3773 11958 3768 11958 3765 11961 3765 11968
      3768 11975 3772 11974 3775 11967

FLASH FLOOD...RADAR INDICATED Additional rainfall amounts up to one 
half inches is expected  over the next hour.

$$

CMc
2 follow-up statements
124 
WGUS76 KHNX 292351
FFSHNX

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

CAC043-300045-
/O.CON.KHNX.FF.W.0008.000000T0000Z-210730T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mariposa CA-
451 PM PDT Thu Jul 29 2021

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM PDT FOR
NORTH CENTRAL MARIPOSA COUNTY...

At 447 PM PDT, Doppler radar indicated the heavy rain has ended over 
the warning area. 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...
Yosemite National, Bridalveil Creek Campground and Badger Pass Ranger
Station.

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 3773 11958 3768 11958 3765 11961 3765 11968
      3768 11975 3772 11974 3775 11967

FLASH FLOOD...RADAR INDICATED

$$

CMc
294 
WGUS76 KHNX 300036
FFSHNX

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

CAC043-300045-
/O.EXP.KHNX.FF.W.0008.000000T0000Z-210730T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mariposa CA-
536 PM PDT Thu Jul 29 2021

...THE FLASH FLOOD WARNING FOR NORTH CENTRAL MARIPOSA COUNTY WILL
EXPIRE AT 545 PM PDT...

Flood waters have receded and flash flooding is no longer expected 
to pose a threat. Please continue to heed any remaining road 
closures.

LAT...LON 3773 11958 3768 11958 3765 11961 3765 11968
      3768 11975 3772 11974 3775 11967

$$

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, 3:21 PM PDTFlash Flood WarningHNXMariposa, Tuolumne84 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.