Alert archive / California / Flash Flood Warnings in 2020

Flash Flood Warning 3, NWS Las Vegas, NV

March 12, 2020San Bernardino County, California; Mohave County, Arizona

NWS Las Vegas, NV issued this flash flood warning at Mar 12, 2020, 4:07 PM PDT for San Bernardino County, California; Mohave County, Arizona. It was in force for 4 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Mar 12, 2020, 4:07 PM PDT (23:07 UTC)
Expired
Mar 12, 2020, 8:00 PM PDT
In force
4 hr
Issued by
NWS Las Vegas, NV
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Mohave County, AZ, San Bernardino County, CA

The radar

The Las Vegas radar (KESX), 120 km from the middle of the area, began a volume at 23:11 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.

What was reported inside it

TimeReportWhereRemark
Mar 12, 7:15 PM PDTFLASH FLOOD1 Wsw Amboy, CAROADWAY FLOODED NEAR AMBOY AND NATIONAL TRAILS HWY WITH ROCKS AND DEBRIS ACROSS ROADWAY.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Las Vegas, NV (KVEF), launched 12:00Z, 11.1 hours before the alert went out and 208 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 12:00Z on 2020-03-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3 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 12:00Z on 2020-03-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -14 square meters per square second.1939587897117136Sfc1 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
3 J/kg
Mixed-layer CIN
-54 J/kg
Mixed-layer LCL
1191 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
-14 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.

796 
WGUS55 KVEF 122307
FFWVEF
AZC015-CAC071-130300-
/O.NEW.KVEF.FF.W.0003.200312T2307Z-200313T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
407 PM PDT Thu Mar 12 2020

The National Weather Service in Las Vegas has issued a

* Flash Flood Warning for...
  Southwestern Mohave County in northwestern Arizona...
  Southeastern San Bernardino County in southern California...

* Until 800 PM PDT/800 PM MST/.

* At 403 PM PDT/403 PM MST/, Doppler radar indicated thunderstorms 
  producing heavy rain across eastern San Bernardino County and 
  southwestern Mohave County. Flash flooding is ongoing or expected 
  to begin shortly.

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

  SOURCE...Radar indicated.

  IMPACT...Life threatening flash flooding of creeks and streams, 
           urban areas, highways, streets and underpasses.

* Some locations that will experience flooding include...
  Lake Havasu City, Highway 95 At Mile Marker 29, Topock, Needles,
  Three Dunes Campground, Desert Hills, Black Meadow Landing
  Campground, Amboy, Mojave Ranch Estates, Mohave Valley, Highway 95
  And I-40, Mesquite Creek, Cattail Cove State Park, Arizona Village,
  Essex and Willow Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3426 11458 3424 11513 3456 11578 3501 11547
      3516 11503 3507 11472 3501 11465 3505 11463
      3497 11436 3467 11425 3428 11415 3419 11423
      3416 11429

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$
CK
2 follow-up statements
205 
WGUS75 KVEF 130015
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
515 PM PDT Thu Mar 12 2020

AZC015-CAC071-130300-
/O.CON.KVEF.FF.W.0003.000000T0000Z-200313T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mohave AZ-San Bernardino CA-
515 PM PDT Thu Mar 12 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 800 PM PDT/800 PM
MST/ FOR SOUTHWESTERN MOHAVE AND SOUTHEASTERN SAN BERNARDINO
COUNTIES...

At 510 PM PDT/510 PM MST/, trained weather spotters reported flash 
flooding in Lake Havasu City along London Bridge Rd near Paseo del 
Sol Ave. Spotter reports one to one and half feet of fast moving 
water moving across the roadway. Flash flooding is ongoing or 
expected to begin shortly.

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

SOURCE...Trained weather spotters.

IMPACT...Life threatening flash flooding of creeks and streams, 
         urban areas, highways, streets and underpasses.

Some locations that will experience flooding include...
Lake Havasu City, Highway 95 At Mile Marker 29, Topock, Needles,
Three Dunes Campground, Desert Hills, Black Meadow Landing
Campground, Amboy, Mojave Ranch Estates, Mohave Valley, Highway 95
And I-40, Mesquite Creek, Cattail Cove State Park, Arizona Village,
Essex and Willow Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3426 11458 3424 11513 3456 11578 3501 11547
      3516 11503 3507 11472 3501 11465 3505 11463
      3497 11436 3467 11425 3428 11415 3419 11423
      3416 11429

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

CK
140 
WGUS75 KVEF 130257
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
757 PM PDT Thu Mar 12 2020

AZC015-CAC071-130303-
/O.EXP.KVEF.FF.W.0003.000000T0000Z-200313T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mohave AZ-San Bernardino CA-
757 PM PDT Thu Mar 12 2020

...THE FLASH FLOOD WARNING FOR SOUTHWESTERN MOHAVE AND SOUTHEASTERN
SAN BERNARDINO COUNTIES WILL EXPIRE AT 800 PM PDT/800 PM MST/...

The heavy rain has ended. Additional flooding is no longer expected 
to pose a threat. Significant ponding of water and rapidly running 
washes will continue overnight. Please continue to heed any 
remaining road closures.

LAT...LON 3426 11458 3424 11513 3456 11578 3501 11547
      3516 11503 3507 11472 3501 11465 3505 11463
      3497 11436 3467 11425 3428 11415 3419 11423
      3416 11429

$$

SC

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 12, 2:54 PM PDTFlash Flood Warning Considerable damage threatVEFSan Bernardino2 hr
Mar 12, 3:26 PM PDTFlash Flood Warning Considerable damage threatVEFSan Bernardino3 hr
Mar 12, 4:32 PM PDTFlash Flood Warning Considerable damage threatVEFSan Bernardino3 hr

Nearby

Flash Flood Warnings in California, 2020Flash Flood Warnings in Arizona, 2020Every flash flood warning in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.