Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 85, NWS Las Vegas, NV

July 30, 2021San Bernardino County, California

NWS Las Vegas, NV issued this flash flood warning at Jul 30, 2021, 2:48 PM PDT for San Bernardino County, California. It was in force for 3 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 30, 2021, 2:48 PM PDT (21:48 UTC)
Expired
Jul 30, 2021, 6:00 PM PDT
In force
3 hr
Issued by
NWS Las Vegas, NV
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County San Bernardino County, CA

The radar

The Santa Ana Mts radar (KSOX), 127 km from the middle of the area, began a volume at 21:51 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.

What was reported inside it

TimeReportWhereRemark
Jul 30, 3:49 PM PDTFLASH FLOOD1 Ne Yucca Valley, CACHP REPORTS MODERATE FLOODING AT THE INTERSECTION OF CR-62 AND CR-247.
Jul 30, 5:45 PM PDTFLASH FLOOD4 E Joshua Tree, CACHP REPORTED ROAD FLOODING AT SUNFAIR RD AND SR-62. VEHICLES ARE SLIDING AND GETTING STUCK.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 9.8 hours before the alert went out and 178 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, San Diego, CA at 12:00Z on 2021-07-30Temperature 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, San Diego, CA at 12:00Z on 2021-07-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -15 square meters per square second.193958Sfc1 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
2147 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
-15 m²/s²
0-3 km storm-relative helicity
37 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

031 
WGUS55 KVEF 302148
FFWVEF
CAC071-310100-
/O.NEW.KVEF.FF.W.0085.210730T2148Z-210731T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
248 PM PDT Fri Jul 30 2021

The National Weather Service in Las Vegas has issued a

* Flash Flood Warning for...
  East Central San Bernardino County in southern California...

* Until 600 PM PDT.

* At 248 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain near Landers with storms building southeast toward 
  Yucca Valley and Joshua Tree. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Life-threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life-threatening flash flooding of low-water
           crossings, creeks, normally dry washes and roads.

* Some locations that will experience flash flooding include...
  Yucca Valley, Joshua Tree and Joshua Tree Lake Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3442 11640 3437 11631 3434 11629 3425 11623
      3415 11620 3412 11621 3412 11626 3408 11626
      3408 11644 3413 11651 3414 11647 3421 11644
      3426 11644 3432 11648 3436 11640

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

BKP
2 follow-up statements
896 
WGUS75 KVEF 302242
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
342 PM PDT Fri Jul 30 2021

CAC071-310100-
/O.CON.KVEF.FF.W.0085.000000T0000Z-210731T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
342 PM PDT Fri Jul 30 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 6 PM PDT THIS EVENING 
FOR EAST CENTRAL SAN BERNARDINO COUNTY...

At 342 PM PDT, Doppler radar indicated a line of thunderstorms 
producing heavy rain between Landers and Joshua Tree. A storm 
spotter in Landers reported around 0.75 inch of rain in 30 minutes. 
Flash flooding is ongoing or expected to begin shortly.

HAZARD...Life-threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar.

IMPACT...Life-threatening flash flooding of low-water crossings,
         creeks, normally dry washes and roads.

Some locations that will experience flash flooding include...
  Yucca Valley, Joshua Tree and Joshua Tree Lake Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3442 11640 3437 11631 3434 11629 3425 11623
      3415 11620 3412 11621 3412 11626 3408 11626
      3408 11644 3413 11651 3414 11647 3421 11644
      3426 11644 3432 11648 3436 11640

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

BKP
961 
WGUS75 KVEF 310056
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
556 PM PDT Fri Jul 30 2021

CAC071-310106-
/O.EXP.KVEF.FF.W.0085.000000T0000Z-210731T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
556 PM PDT Fri Jul 30 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 6 PM PDT THIS EVENING FOR EAST 
CENTRAL SAN BERNARDINO COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 500 AM PDT Sunday for a 
portion of southeast California.

LAT...LON 3442 11640 3437 11631 3434 11629 3425 11623
      3415 11620 3412 11621 3412 11626 3408 11626
      3408 11644 3413 11651 3414 11647 3421 11644
      3426 11644 3432 11648 3436 11640

$$

BKP

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 30, 1:14 PM PDTSevere Thunderstorm WarningVEFSan Bernardino61 min
Jul 30, 2:53 PM PDTAreal Flood AdvisoryVEFInyo3 hr
Jul 30, 3:56 PM PDTFlash Flood Warning Considerable damage threatVEFInyo5 hr
Jul 30, 4:07 PM PDTFlash Flood Warning Considerable damage threatVEFSan Bernardino3 hr

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.