Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 29, NWS Las Vegas, NV

July 18, 2021San Bernardino County, California

NWS Las Vegas, NV issued this flash flood warning at Jul 18, 2021, 7:10 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, 7:10 PM PDT (02:10 UTC)
Expired: Jul 18, 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 Edwards AFB radar (KEYX), 70 km from the middle of the area, began a volume at 02:13 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, 2.2 hours before the alert went out and 207 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.

882 
WGUS55 KVEF 190210
FFWVEF
CAC071-190500-
/O.NEW.KVEF.FF.W.0029.210719T0210Z-210719T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
710 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 1000 PM PDT.

* At 710 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across Daggett and Newberry Springs. A spotter reported 
  flash flooding along Route 66 in Newberry Springs. Flash flooding 
  is occurring 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...
  Daggett, Newberry Springs and Nebo Center.

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 3479 11702 3491 11694 3495 11685 3491 11663
      3476 11668

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

$$

CP

2 follow-up statements

303 
WGUS75 KVEF 190308
FFSVEF

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

CAC071-190500-
/O.CON.KVEF.FF.W.0029.000000T0000Z-210719T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
808 PM PDT Sun Jul 18 2021

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

At 808 PM PDT, the public reported flash flooding across Highway 66 
near Daggett. CHP also reported signs of flooding with debris along 
Main Street and I-15.

HAZARD...Life-threatening flash flooding. Heavy rain producing
         flash flooding.

SOURCE...Public reported and CHP.

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

Some locations that will experience flash flooding include...
  Daggett, Newberry Springs and Nebo Center.

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 3479 11702 3491 11694 3495 11685 3491 11663
      3476 11668

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

CP

251 
WGUS75 KVEF 190451
FFSVEF

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

CAC071-190501-
/O.EXP.KVEF.FF.W.0029.000000T0000Z-210719T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Bernardino CA-
951 PM PDT Sun Jul 18 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 10 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 3479 11702 3491 11694 3495 11685 3491 11663
      3476 11668

$$

CP

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 5:35 PM PDT	Flash Flood Warning Considerable damage threat	VEF	San Bernardino	3 hr
Jul 18, 6:24 PM PDT	Areal Flood Advisory	VEF	San Bernardino	47 min
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.