Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 18, NWS Las Vegas, NV

July 17, 2021Mohave County, Arizona

NWS Las Vegas, NV issued this flash flood warning at Jul 17, 2021, 4:40 PM MST for 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 as issued.

The facts

Issued
Jul 17, 2021, 4:40 PM MST (23:40 UTC)
Expired
Jul 17, 2021, 7:45 PM MST
In force
3 hr
Issued by
NWS Las Vegas, NV
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Mohave County, AZ

The radar

The Las Vegas radar (KESX), 76 km from the middle of the area, began a volume at 23:42 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 12:00Z, 11.7 hours before the alert went out and 154 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 2021-07-17Temperature 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, Las Vegas, NV at 12:00Z on 2021-07-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -25 square meters per square second.1939Sfc1 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
3507 m above ground
0-6 km bulk shear
4 kt
0-1 km storm-relative helicity
-25 m²/s²
0-3 km storm-relative helicity
16 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

474 
WGUS55 KVEF 172340
FFWVEF
AZC015-180245-
/O.NEW.KVEF.FF.W.0018.210717T2340Z-210718T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
440 PM PDT Sat Jul 17 2021

The National Weather Service in Las Vegas has issued a

* Flash Flood Warning for...
  West Central Mohave County in northwestern Arizona...

* Until 745 PM MST.

* At 440 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across portions of Pierce Ferry Rd, Diamond Bar Rd, and 
  Stockton Hill Rd. 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...
  Pierce Ferry And Antares Roads and Dolan Springs.

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 3572 11387 3564 11386 3560 11393 3550 11396
      3542 11403 3543 11411 3548 11420 3576 11429
      3601 11431 3602 11415 3591 11407

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

$$

CP
2 follow-up statements
438 
WGUS75 KVEF 180154
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
654 PM PDT Sat Jul 17 2021

AZC015-180245-
/O.CON.KVEF.FF.W.0018.000000T0000Z-210718T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mohave AZ-
654 PM MST Sat Jul 17 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 745 PM MST THIS 
EVENING FOR WEST CENTRAL MOHAVE COUNTY...

At 654 PM MST, the thunderstorms that produced heavy rainfall have 
moved out of the area. However, radar indicated several areas saw 
over an inch of rainfall leading to potential flash flooding along 
flood-prone roadways. 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...
  Pierce Ferry, Antares Roads and Diamond Bar Road.

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 3572 11387 3564 11386 3560 11393 3550 11396
      3542 11403 3543 11411 3548 11420 3576 11429
      3601 11431 3602 11415 3591 11407

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

$$

CP
831 
WGUS75 KVEF 180245
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
745 PM PDT Sat Jul 17 2021

AZC015-180255-
/O.EXP.KVEF.FF.W.0018.000000T0000Z-210718T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mohave AZ-
745 PM MST Sat Jul 17 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR WEST CENTRAL MOHAVE COUNTY...

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

LAT...LON 3572 11387 3564 11386 3560 11393 3550 11396
      3542 11403 3543 11411 3548 11420 3576 11429
      3601 11431 3602 11415 3591 11407

$$

CP

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 17, 1:32 PM MSTFlash Flood Warning Considerable damage threatVEFMohave108 min
Jul 17, 2:08 PM MSTFlash Flood Warning Considerable damage threatVEFMohave3 hr
Jul 17, 3:53 PM MSTFlash Flood Warning Considerable damage threatVEFMohave3 hr

Nearby

Flash Flood Warnings in Arizona, 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.