Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 64, NWS Las Vegas, NV

July 25, 2021San Bernardino County, California

NWS Las Vegas, NV issued this flash flood warning at Jul 25, 2021, 6:59 PM PDT for San Bernardino 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 25, 2021, 6:59 PM PDT (01:59 UTC)
Expired
Jul 25, 2021, 10:00 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 Las Vegas radar (KESX), 81 km from the middle of the area, began a volume at 02:04 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

Las Vegas, NV (KVEF), launched 00:00Z, 2.0 hours before the alert went out and 129 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, Las Vegas, NV at 00:00Z on 2021-07-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 707 joules per kilogram.LCLLFCEL10008507005003002001001 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, Las Vegas, NV at 00:00Z on 2021-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 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
707 J/kg
Mixed-layer CIN
-44 J/kg
Mixed-layer LCL
2729 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
81 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

900 
WGUS55 KVEF 260159
FFWVEF
CAC071-260500-
/O.NEW.KVEF.FF.W.0064.210726T0159Z-210726T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
659 PM PDT Sun Jul 25 2021

The National Weather Service in Las Vegas has issued a

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

* Until 1000 PM PDT.

* At 659 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the Mojave Preserve. 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...
  Kelso, Cima, Mitchell Caverns, Mid Hills Campground, Hole In The 
  Wall Campground, Black Canyon Equestrian Campground, Nipton And 
  Ivanpah Roads and Nipton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 3547 11542 3549 11527 3522 11521 3477 11561
      3480 11587 3515 11603 3538 11564

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

$$

CP
2 follow-up statements
578 
WGUS75 KVEF 260336
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
836 PM PDT Sun Jul 25 2021

CAC071-260500-
/O.CON.KVEF.FF.W.0064.000000T0000Z-210726T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
836 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 10 PM PDT THIS 
EVENING FOR SAN BERNARDINO COUNTY...

At 836 PM PDT, Most of the heavy rain has ended across the Mojave 
Preserve, but over an inch and a half fell across Kelso Cima Road. 
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...
  Kelso, Cima, Mitchell Caverns, Mid Hills Campground, Hole In The 
  Wall Campground, Black Canyon Equestrian Campground, Nipton And 
  Ivanpah Roads and Nipton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 3547 11542 3549 11527 3522 11521 3477 11561
      3480 11587 3515 11603 3538 11564

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

$$

CP
892 
WGUS75 KVEF 260453
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
953 PM PDT Sun Jul 25 2021

CAC071-260503-
/O.EXP.KVEF.FF.W.0064.000000T0000Z-210726T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
953 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 10 PM PDT THIS EVENING FOR SAN 
BERNARDINO COUNTY...

Flood waters have receded. 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 1100 PM PDT Monday for 
portions of southeast California and southern Nevada.

LAT...LON 3547 11542 3549 11527 3522 11521 3477 11561
      3480 11587 3515 11603 3538 11564

$$

JV

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 25, 9:55 PM PDTSevere Thunderstorm WarningVEFInyo, San Bernardino50 min
Jul 25, 11:13 PM PDTFlash Flood Warning Considerable damage threatVEFInyo, San Bernardino3 hr
Jul 26, 7:59 AM PDTAreal Flood AdvisoryVEFSan Bernardino3 hr
Jul 26, 8:12 AM PDTFlash Flood Warning Considerable damage threatVEFSan Bernardino3 hr
Jul 26, 9:26 AM PDTAreal Flood AdvisoryVEFSan Bernardino3 hr
Jul 26, 10:44 AM PDTFlash Flood Warning Considerable damage threatVEFInyo, San Bernardino3 hr
Jul 26, 11:36 AM PDTFlash Flood Warning Considerable damage threatVEFInyo, San Bernardino3 hr
Jul 26, 12:29 PM PDTFlash Flood Warning Considerable damage threatVEFInyo3 hr
Jul 26, 12:51 PM PDTFlash Flood Warning Considerable damage threatVEFInyo, San Bernardino3 hr
Jul 26, 1:12 PM PDTFlash Flood Warning Considerable damage threatVEFInyo4 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.