Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 125, NWS Las Vegas, NV

August 31, 2021San Bernardino County, California

NWS Las Vegas, NV issued this flash flood warning at Aug 31, 2021, 5:25 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
Aug 31, 2021, 5:25 PM PDT (00:25 UTC)
Expired
Aug 31, 2021, 8:30 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 San Diego radar (KNKX), 177 km from the middle of the area, began a volume at 00:28 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

San Diego, CA (KNKX), launched 00:00Z, 0.4 hours before the alert went out and 197 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 00:00Z on 2021-09-01Temperature 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 00:00Z on 2021-09-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -77 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
853 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-77 m²/s²
0-3 km storm-relative helicity
-65 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

944 
WGUS55 KVEF 010025
FFWVEF
CAC071-010330-
/O.NEW.KVEF.FF.W.0125.210901T0025Z-210901T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
525 PM PDT Tue Aug 31 2021

The National Weather Service in Las Vegas has issued a

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

* Until 830 PM PDT.

* At 525 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. 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...
  State Route 62 (Twentynine Palms Highway) east of Twentynine Palms.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3404 11589 3413 11588 3413 11577 3410 11558
      3409 11558 3409 11559 3409 11560 3407 11561
      3404 11560 3404 11567 3404 11568 3404 11569
      3404 11572 3404 11574 3404 11575 3404 11584

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

$$

JV
2 follow-up statements
251 
WGUS75 KVEF 010137
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
637 PM PDT Tue Aug 31 2021

CAC071-010330-
/O.CON.KVEF.FF.W.0125.000000T0000Z-210901T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
637 PM PDT Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 830 PM PDT THIS 
EVENING FOR SAN BERNARDINO COUNTY...

At 637 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain continue to push northward into the warned area. Flash flooding 
is ongoing or expected to begin shortly along State Route 62.

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...
  State Route 62 (Twentynine Palms Highway) east of Twentynine Palms.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3404 11589 3413 11588 3413 11577 3410 11558
      3409 11558 3409 11559 3409 11560 3407 11561
      3404 11560 3404 11567 3404 11568 3404 11569
      3404 11572 3404 11574 3404 11575 3404 11584

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

$$

JV
568 
WGUS75 KVEF 010326
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
826 PM PDT Tue Aug 31 2021

CAC071-010336-
/O.EXP.KVEF.FF.W.0125.000000T0000Z-210901T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
826 PM PDT Tue Aug 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 830 PM PDT THIS EVENING FOR 
SAN BERNARDINO COUNTY...

The heavy rain has ended, but light to moderate rain continues over 
the area. Continue to heed road closures, if applicable. Flood 
waters are hard to see at night, so drive carefully over State Route 
62 east of Twentynine Palms.

A Flash Flood Watch remains in effect until 200 AM PDT for a portion 
of southeast California.

LAT...LON 3404 11589 3413 11588 3413 11577 3410 11558
      3409 11558 3409 11559 3409 11560 3407 11561
      3404 11560 3404 11567 3404 11568 3404 11569
      3404 11572 3404 11574 3404 11575 3404 11584

$$

JV

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 31, 7:08 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.