Alert archive / Nevada / Flash Flood Warnings in 2012

Flash Flood Warning 201, NWS Las Vegas, NV

September 11, 2012Clark County, Nevada

NWS Las Vegas, NV issued this flash flood warning at Sep 11, 2012, 1:51 PM PDT for Clark County, Nevada. It was in force for 114 min. 6 reports 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
Sep 11, 2012, 1:51 PM PDT (20:51 UTC)
Expired
Sep 11, 2012, 3:45 PM PDT
In force
114 min
Issued by
NWS Las Vegas, NV
Area
Storm-based polygon
Flood severity
None

County Clark County, NV

The radar

The Las Vegas radar (KESX), 38 km from the middle of the area, began a volume at 20:52 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
Sep 11, 2:00 PM PDTFLASH FLOOD4 W Green Valley, NVNEVADA HIGHWAY PATROL CLOSED 215 FROM I-15 TO WARM SPRINGS. THE AIRPORT CONNECTOR WAS CLOSED DUE TO A LARGE AMOUNT OF MUD AND ROCKS THAT WASHED DOWN THE SIDES OF THE ROAD FROM LANDSCAPED AREAS.
Sep 11, 2:12 PM PDTFLASH FLOOD3 Sse Henderson, NVSPOTTER REPORTED WATER FLOWING 6 INCHES DEEP AT THE INTERSECTION OF GREENWAY AND TRENIER. TRAFFIC CONTROL CONES AND BARRICADES WERE FLOATING IN THE WATER.
Sep 11, 2:33 PM PDTFLASH FLOOD3 Sse Green Valley, NVNWS EMPLOYEE REPORTS LARGE AMOUNT OF WATER MOVING ACROSS ARROYO GRANDE BETWEEN HORIZON RIDGE PARKWAY AND 215. WATER ALSO FLOWING ACROSS HORIZON RIDGE NEAR THE POST OFFICE.
Sep 11, 2:33 PM PDTHEAVY RAIN 0.52 Ese Henderson, NVSPOTTER REPORTED 0.50 INCHES OF WATER IN 30 MINUTES.
Sep 11, 2:35 PM PDTFLASH FLOOD2 Se Henderson, NVSPOTTER REPORTS THAT THE INTERSECTION OF WARM SPRINGS AND EASTERN IS IMPASSABLE. ALSO REPORTS AT LEWIS AND CASINO CENTER 3 TO 4 INCHES OF WATER IS FLOWING ACROSS ROAD.
Sep 11, 2:51 PM PDTHEAVY RAIN 0.793 Sse Henderson, NVTRAINED SPOTTER REPORTED 0.79 INCHES OF RAIN IN THE LAST HOUR.

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, 8.9 hours before the alert went out and 61 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 2012-09-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2 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 2012-09-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 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
2 J/kg
Mixed-layer CIN
-171 J/kg
Mixed-layer LCL
1725 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
37 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.

600 
WGUS55 KVEF 112051
FFWVEF
NVC003-112245-
/O.NEW.KVEF.FF.W.0201.120911T2051Z-120911T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE LAS VEGAS NV
151 PM PDT TUE SEP 11 2012

THE NATIONAL WEATHER SERVICE IN LAS VEGAS HAS ISSUED A

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

* UNTIL 345 PM PDT.

* AT 143 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  VERY HEAVY RAIN FROM A THUNDERSTORM EXTENDING FROM THE NORTHERN    
  STRIP IN THE CENTRAL VALLEY TO SOUTH OF ANTHEM IN THE SOUTHERN     
  PORTION OF THE VALLEY AND WAS MOVING TO THE EAST AT 15 MPH.

* LOCATIONS IMPACTED INCLUDE...
  CENTRAL...EASTERN AND SOUTHERN LAS VEGAS...HENDERSON...GREEN       
  VALLEY.

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.

&&

LAT...LON 3610 11494 3590 11494 3590 11515 3610 11517

$$

JS
2 follow-up statements
776 
WGUS75 KVEF 112145
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
245 PM PDT TUE SEP 11 2012

NVC003-112245-
/O.CON.KVEF.FF.W.0201.000000T0000Z-120911T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
245 PM PDT TUE SEP 11 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 345 PM PDT FOR
CENTRAL CLARK COUNTY...

AT 239 PM PDT...RADAR INDICATED HEAVY RAIN MOVING AWAY FROM 
HENDERSON. SEVERAL TRAINED WEATHER SPOTTERS HAVE REPORTED FLASH 
FLOODING OCCURRING IN THE AREA...AND THE FLASH FLOOD WARNING REMAINS 
IN EFFECT UNTIL 345 PM.

LOCATIONS IMPACTED INCLUDE...
HENDERSON.

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.

&&

LAT...LON 3610 11494 3590 11494 3590 11515 3610 11517

$$

MORGAN
371 
WGUS75 KVEF 112240
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
340 PM PDT TUE SEP 11 2012

NVC003-112250-
/O.EXP.KVEF.FF.W.0201.000000T0000Z-120911T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
340 PM PDT TUE SEP 11 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 345 PM PDT FOR CENTRAL
CLARK COUNTY...

THE FLASH FLOOD WARNING FOR THE SOUTHEAST LAS VEGAS VALLEY HAS 
EXPIRED AND BEEN REPLACED BY A NEW FLASH FLOOD WARNING VALID UNTIL 
545 PM.

LAT...LON 3610 11494 3590 11494 3590 11515 3610 11517

$$

MORGAN

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 11, 3:24 AM PDTFlash Flood WarningVEFClark111 min
Sep 11, 4:52 AM PDTFlash Flood WarningVEFNye113 min
Sep 11, 8:28 AM PDTAreal Flood AdvisoryVEFLincoln3 hr
Sep 11, 11:33 AM PDTAreal Flood AdvisoryVEFClark3 hr
Sep 11, 12:32 PM PDTFlash Flood WarningVEFClark88 min
Sep 11, 1:44 PM PDTAreal Flood AdvisoryVEFClark27 min
Sep 11, 2:08 PM PDTFlash Flood WarningVEFClark93 min
Sep 11, 2:16 PM PDTSevere Thunderstorm WarningVEFClark44 min
Sep 11, 2:18 PM PDTFlash Flood WarningVEFClark4 hr
Sep 11, 3:39 PM PDTFlash Flood WarningVEFClark2 hr
Sep 11, 4:02 PM PDTFlash Flood WarningVEFClark118 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.