Alert archive / Nevada / Flash Flood Warnings in 2021

Flash Flood Warning 66, NWS Las Vegas, NV

July 25, 2021Clark County, Nevada

NWS Las Vegas, NV issued this flash flood warning at Jul 25, 2021, 8:59 PM PDT for Clark County, Nevada. It was in force for 3 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: Jul 25, 2021, 8:59 PM PDT (03:59 UTC)
Expired: Jul 26, 2021, 12:00 AM PDT
In force: 3 hr
Issued by: NWS Las Vegas, NV
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Clark County, NV

The radar

The Las Vegas radar (KESX), 35 km from the middle of the area, began a volume at 03:59 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

Time	Report	Where	Remark
Jul 25, 9:15 PM PDT	FLASH FLOOD	1 Sse Boulder Beach, NV	1.5-2.5 FEET OF DEBRIS AND BASKETBALL-SIZED ROCKS WERE REPORTED ON SECTIONS OF LAKESHORE ROAD, BOULDER BEACH FRONTAGE ROAD AND NEARBY NORTHSHORE ROAD DUE TO FLASH FLOODING.

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 00:00Z, 4.0 hours before the alert went out and 62 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: 707 J/kg
Mixed-layer CIN: -44 J/kg
Mixed-layer LCL: 2729 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 17 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.

515 
WGUS55 KVEF 260359
FFWVEF
NVC003-260700-
/O.NEW.KVEF.FF.W.0066.210726T0359Z-210726T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Las Vegas NV
859 PM PDT Sun Jul 25 2021

The National Weather Service in Las Vegas has issued a

* Flash Flood Warning for...
  Central Clark County in southern Nevada...

* Until midnight PDT.

* At 859 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the Las Vegas Valley. 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...
  Las Vegas, Henderson, North Las Vegas, Boulder City, Paradise, 
  Enterprise, The Strip, Green Valley, Southern Highlands, Anthem, 
  Spring Valley, Downtown Las Vegas, Mountains Edge, Sam Boyd 
  Stadium, East Las Vegas, Summerlin, Nellis AFB, Lake Las Vegas, 
  Lone Mountain and Aliante.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3602 11473 3598 11474 3596 11473 3574 11491
      3560 11537 3563 11541 3600 11547 3648 11544
      3643 11500

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

$$

CP

2 follow-up statements

910 
WGUS75 KVEF 260425
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
925 PM PDT Sun Jul 25 2021

NVC003-260700-
/O.CON.KVEF.FF.W.0066.000000T0000Z-210726T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clark NV-
925 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL MIDNIGHT PDT TONIGHT 
FOR CENTRAL CLARK COUNTY...

At 925 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across southern portions of the Las Vegas Valley. Flood control 
gauges have recorded water levels of 4 to 6 feet in a few drainage 
basins near and in Old Henderson. Flooding has also been reported 
across parts of Old Henderson. 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...
  Las Vegas, Henderson, North Las Vegas, Boulder City, Paradise, 
  Enterprise, The Strip, Green Valley, Southern Highlands, Anthem, 
  Spring Valley, Downtown Las Vegas, Mountains Edge, Sam Boyd 
  Stadium, East Las Vegas, Summerlin, Nellis AFB, Lake Las Vegas, 
  Lone Mountain and Aliante.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3602 11473 3598 11474 3596 11473 3574 11491
      3560 11537 3563 11541 3600 11547 3648 11544
      3643 11500

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

$$

CP

524 
WGUS75 KVEF 260657
FFSVEF

Flash Flood Statement
National Weather Service Las Vegas NV
1157 PM PDT Sun Jul 25 2021

NVC003-260707-
/O.EXP.KVEF.FF.W.0066.000000T0000Z-210726T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clark NV-
1157 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT MIDNIGHT PDT TONIGHT FOR 
CENTRAL CLARK COUNTY...

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

A Flash Flood Watch remains in effect until 1100 PM PDT Monday for 
portions of southeast California and southern Nevada.

LAT...LON 3602 11473 3598 11474 3596 11473 3574 11491
      3560 11537 3563 11541 3600 11547 3648 11544
      3643 11500

$$

CP

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 25, 5:12 PM PDT	Dust Storm Warning	VEF	Clark	63 min
Jul 25, 5:37 PM PDT	Flash Flood Warning Considerable damage threat	VEF	Lincoln	3 hr
Jul 25, 6:01 PM PDT	Severe Thunderstorm Warning	VEF	Clark	59 min
Jul 25, 6:06 PM PDT	Severe Thunderstorm Warning	VEF	Lincoln	39 min
Jul 25, 7:08 PM PDT	Severe Thunderstorm Warning	VEF	Clark	52 min
Jul 25, 7:57 PM PDT	Severe Thunderstorm Warning	VEF	Clark, Lincoln	63 min
Jul 25, 8:09 PM PDT	Flash Flood Warning Considerable damage threat	VEF	Clark	3 hr
Jul 25, 8:59 PM PDT	Severe Thunderstorm Warning	VEF	Clark, Nye	61 min
Jul 25, 9:55 PM PDT	Severe Thunderstorm Warning	VEF	Clark, Nye	50 min
Jul 26, 10:20 AM PDT	Flash Flood Warning Considerable damage threat	VEF	Clark	3 hr
Jul 26, 10:44 AM PDT	Flash Flood Warning Considerable damage threat	VEF	Clark	3 hr
Jul 26, 11:32 AM PDT	Flash Flood Warning Considerable damage threat	VEF	Clark, Nye	4 hr
Jul 26, 12:29 PM PDT	Flash Flood Warning Considerable damage threat	VEF	Nye	3 hr
Jul 26, 12:40 PM PDT	Flash Flood Warning Considerable damage threat	VEF	Nye	3 hr
Jul 26, 1:28 PM PDT	Flash Flood Warning Considerable damage threat	VEF	Lincoln	3 hr
Jul 26, 2:05 PM PDT	Severe Thunderstorm Warning	VEF	Lincoln	40 min
Jul 26, 4:30 PM PDT	Flash Flood Warning Considerable damage threat	VEF	Lincoln	2 hr
Jul 26, 4:34 PM PDT	Severe Thunderstorm Warning	VEF	Lincoln	41 min

Nearby

Flash Flood Warnings in Nevada, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.