Alert archive / California / Flash Flood Warnings in 2001

Flash Flood Warning 18, NWS Las Vegas, NV

August 12, 2001San Bernardino County, California; Mohave County, Arizona

NWS Las Vegas, NV issued this flash flood warning at Aug 12, 2001, 6:42 PM PDT for San Bernardino County, California; Mohave County, Arizona. 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 the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties.

The facts

Issued: Aug 12, 2001, 6:42 PM PDT (01:42 UTC)
Expired: Aug 12, 2001, 10:00 PM PDT
In force: 3 hr
Issued by: NWS Las Vegas, NV
Area: Whole counties; the outline is the Mesonet’s reconstruction

Counties Mohave County, AZ, San Bernardino County, CA

The radar

The Las Vegas radar (KESX), 83 km from the middle of the area, began a volume at 01:45 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

Mercury/Desert R, NV (KDRA), launched 00:00Z, 1.7 hours before the alert went out and 217 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: 324 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 3814 m above ground
0-6 km bulk shear: 4 kt
0-1 km storm-relative helicity: 6 m²/s²
0-3 km storm-relative helicity: -64 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WGUS55 KVEF 130147
FFWLAS
AZC015-CAC071-130445-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE LAS VEGAS NV
642 PM PDT SUN AUG 12 2001

THE NATIONAL WEATHER SERVICE IN LAS VEGAS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EXTREME SOUTHWESTERN MOHAVE COUNTY IN NORTHWEST ARIZONA
  THIS INCLUDES THE FOLLOWING LOCATION...TOPOCK
  EXTREME EASTERN SAN BERNARDINO COUNTY IN SOUTHEAST CALIFORNIA
  THIS INCLUDES THE FOLLOWING LOCATION...NEEDLES
 
* UNTIL 1000 PM PDT(1000 PM MST)

* AT 642 PM PDT(642 PM MST)...NATIONAL WEATHER SERVICE DOPPLER 
  RADAR INDICATED THUNDERSTORMS WITH VERY HEAVY RAIN OVER NEEDLES
  AND MOHAVE VALLEY...MOVING SOUTH AT 5 MPH.

EXCESSIVE RUNOFF FROM THESE STORMS WILL CAUSE FLASH FLOODING OF 
ROADWAYS...WASHES AND NARROW CANYONS. THE HEAVY RAINS COULD ALSO 
TRIGGER ROCK AND MUDSLIDES IN STEEP TERRAIN.

NEVER DRIVE YOUR VEHICLE INTO AREAS WHERE WATER COVERS THE ROADWAY.
IT ONLY TAKES A FOOT OR TWO OF FLOWING WATER TO WASH MOST CARS AWAY.
VEHICLES CAUGHT IN RISING WATER SHOULD BE ABANDONED QUICKLY.

LAT...LON 3523 11494 3454 11472 3474 11440 3512 11452

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 12, 5:28 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	62 min
Aug 12, 8:38 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	67 min

Nearby

Flash Flood Warnings in California, 2001 Flash Flood Warnings in Arizona, 2001 Every flash flood warning in 2001

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.