Alert archive / Nevada / Flash Flood Warnings in 2012

Flash Flood Warning 120, NWS Las Vegas, NV

August 17, 2012Clark County, Nevada

NWS Las Vegas, NV issued this flash flood warning at Aug 17, 2012, 11:39 PM PDT for Clark County, Nevada. It was in force for 2 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
Aug 17, 2012, 11:39 PM PDT (06:39 UTC)
Expired
Aug 18, 2012, 1:45 AM PDT
In force
2 hr
Issued by
NWS Las Vegas, NV
Area
Storm-based polygon
Flood severity
None

County Clark County, NV

The radar

The Las Vegas radar (KESX), 66 km from the middle of the area, began a volume at 06:41 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
Aug 18, 12:11 AM PDTFLASH FLOOD4 W Las Vegas, NVWATER AT LEAST SIX TO EIGHT INCHES DEEP WAS FLOWING THROUGH THE INTERSECTION OF WASHINGTON AND MICHAEL.

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, 6.7 hours before the alert went out and 32 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 00:00Z on 2012-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 49 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 00:00Z on 2012-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -38 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
49 J/kg
Mixed-layer CIN
-111 J/kg
Mixed-layer LCL
3156 m above ground
0-6 km bulk shear
5 kt
0-1 km storm-relative helicity
-38 m²/s²
0-3 km storm-relative helicity
40 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.

915 
WGUS55 KVEF 180639
FFWVEF
NVC003-180845-
/O.NEW.KVEF.FF.W.0120.120818T0639Z-120818T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE LAS VEGAS NV
1139 PM PDT FRI AUG 17 2012

THE NATIONAL WEATHER SERVICE IN LAS VEGAS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL CLARK COUNTY IN SOUTHERN NEVADA...

* UNTIL 145 AM PDT.

* AT 1133 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR    
  INDICATED VERY HEAVY RAIN FROM A THUNDERSTORM NEAR NORTH LAS VEGAS 
  AIRPORT AND HIGHWAY 95 AND CHEYENNE BOULEVARD.
  THE STORM PRODUCING VERY HEAVY RAIN WAS NEARLY STATIONARY.

* LOCATIONS IMPACTED INCLUDE...
  CENTENNIAL HILLS...CHEYENNE AND 95 AND THE RAINBOW CURVE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FLASH FLOODING IS EXPECTED ON AREA ROADWAYS...AROUND UNDERPASSES...
AND IN NORMALLY DRY WASHES AND LOW LYING AREAS. FLASH FLOODING IS
NATURES NUMBER ONE KILLER. NEVER TRY TO CROSS A FLOODED ROADWAY OR
WALK THROUGH FLOODWATERS. TURN AROUND...DONT DROWN!

REPORT FLOODING BY POSTING YOUR REPORT TO THE LAS VEGAS NATIONAL
WEATHER SERVICE FACEBOOK PAGE...OR BY USING THE TWITTER HASHTAG...
NWSVEGAS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS EVEN HARDER TO SEE WATER
COVERING THE ROADWAY OR IN LOW WATER CROSSINGS.

&&

LAT...LON 3628 11527 3628 11517 3616 11519 3616 11524

$$

JA
2 follow-up statements
120 
WGUS75 KVEF 180724
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
1224 AM PDT SAT AUG 18 2012

NVC003-180845-
/O.CON.KVEF.FF.W.0120.000000T0000Z-120818T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
1224 AM PDT SAT AUG 18 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 145 AM PDT FOR
CENTRAL CLARK COUNTY...

NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED THAT HEAVY RAINFALL 
IN THE NORTHWEST PART OF THE LAS VEGAS VALLEY BETWEEN THE RAINBOW
CURVE AND CHEYENNE AVENUE WAS DECREASING AND MOVING TO THE WEST.
THE HEAVIEST RAIN FELL BETWEEN DECATUR AND HIGHWAY 95. AUTOMATED 
GAUGES AND RADAR ESTIMATES INDICATE UP TO THREE-QUARTERS OF AN INCH 
OF RAIN FELL. FLOWING WATER BETWEEN 6 TO 8 INCHES DEEP WAS OBSERVED 
AT WASHINGTON AVENUE AND MICHAEL WAY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FLASH FLOODING IS EXPECTED ON AREA ROADWAYS...AROUND UNDERPASSES...
AND IN NORMALLY DRY WASHES AND LOW LYING AREAS. FLASH FLOODING IS
NATURES NUMBER ONE KILLER. NEVER TRY TO CROSS A FLOODED ROADWAY OR
WALK THROUGH FLOODWATERS. TURN AROUND...DONT DROWN!

REPORT FLOODING BY POSTING YOUR REPORT TO THE LAS VEGAS NATIONAL
WEATHER SERVICE FACEBOOK PAGE...OR BY USING THE TWITTER HASHTAG...
NWSVEGAS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS EVEN HARDER TO SEE WATER
COVERING THE ROADWAY OR IN LOW WATER CROSSINGS.

&&

LAT...LON 3624 11524 3626 11518 3616 11519 3616 11524

$$

JA
534 
WGUS75 KVEF 180843
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
143 AM PDT SAT AUG 18 2012

NVC003-180846-
/O.EXP.KVEF.FF.W.0120.000000T0000Z-120818T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
143 AM PDT SAT AUG 18 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 145 AM PDT FOR CENTRAL
CLARK COUNTY...

RUNOFF HAS HAD TIME TO RECEDE IN THE NORTHWEST PART OF THE LAS VEGAS 
VALLEY BETWEEN NORTH LAS VEGAS AIRPORT AND HIGHWAY 95 WHERE HEAVY 
RAIN FELL BEFORE MIDNIGHT. SOME PONDING OF WATER MAY STILL REMAIN IN 
LOW LYING AREAS BUT SIGNIFICANT FLASH FLOODING HAS ENDED.

LAT...LON 3624 11524 3626 11518 3616 11519 3616 11524

$$

JA

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 17, 8:32 PM PDTFlash Flood WarningVEFClark, Lincoln4 hr
Aug 18, 12:01 PM PDTAreal Flood AdvisoryVEFClark119 min
Aug 18, 2:00 PM PDTAreal Flood AdvisoryVEFNye2 hr
Aug 18, 3:26 PM PDTAreal Flood AdvisoryVEFClark, Nye54 min
Aug 18, 3:39 PM PDTFlash Flood WarningVEFClark63 min
Aug 18, 4:18 PM PDTFlash Flood WarningVEFNye53 min
Aug 18, 4:24 PM PDTFlash Flood WarningVEFNye96 min

Nearby

Flash Flood Warnings in Nevada, 2012Every flash flood warning in 2012

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.