Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 26, NWS Las Vegas, NV

July 18, 2021San Bernardino County, California

NWS Las Vegas, NV issued this flash flood warning at Jul 18, 2021, 5:35 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 18, 2021, 5:35 PM PDT (00:35 UTC)
Expired: Jul 18, 2021, 8:45 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), 121 km from the middle of the area, began a volume at 00:35 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, 0.6 hours before the alert went out and 106 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 470 J/kg
Mixed-layer CIN: -221 J/kg
Mixed-layer LCL: 2357 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -43 m²/s²
0-3 km storm-relative helicity: -38 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

549 
WGUS55 KVEF 190035
FFWVEF
CAC071-190345-
/O.NEW.KVEF.FF.W.0026.210719T0035Z-210719T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
535 PM PDT Sun Jul 18 2021

The National Weather Service in Las Vegas has issued a

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

* Until 845 PM PDT.

* At 535 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across Highway 127 near Dumont Dunes. 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...
  Dumont Dunes and Sr 127 Near Dumont Dunes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3544 11607 3540 11621 3567 11637 3577 11636
      3578 11629 3570 11623

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

$$

CP

2 follow-up statements

743 
WGUS75 KVEF 190327
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
827 PM PDT Sun Jul 18 2021

CAC071-190345-
/O.CON.KVEF.FF.W.0026.000000T0000Z-210719T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
827 PM PDT Sun Jul 18 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM PDT THIS 
EVENING FOR SAN BERNARDINO COUNTY...

At 827 PM PDT, A few isolated showers developed over Highway 127 
near Dumont Dunes. Radar indicated an additional 0.30" to 0.50" has 
fallen where over 1.25" previously fell. 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...
  Dumont Dunes and Sr 127 Near Dumont Dunes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3544 11607 3540 11621 3567 11637 3577 11636
      3578 11629 3570 11623

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

$$

CP

100 
WGUS75 KVEF 190338
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
838 PM PDT Sun Jul 18 2021

CAC071-190348-
/O.EXP.KVEF.FF.W.0026.000000T0000Z-210719T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
838 PM PDT Sun Jul 18 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 845 PM PDT THIS EVENING FOR 
SAN BERNARDINO COUNTY...

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

LAT...LON 3544 11607 3540 11621 3567 11637 3577 11636
      3578 11629 3570 11623

$$

CP

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 6:24 PM PDT	Areal Flood Advisory	VEF	San Bernardino	47 min
Jul 18, 7:10 PM PDT	Flash Flood Warning Considerable damage threat	VEF	San Bernardino	3 hr
Jul 19, 2:37 AM PDT	Flash Flood Watch	VEF	Inyo	17 hr
Jul 19, 2:42 PM PDT	Flash Flood Warning Considerable damage threat	VEF	Inyo	3 hr

Nearby

Flash Flood Warnings in California, 2021 Every 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.