Alert archive / Nevada / Flash Flood Warnings in 2011

Flash Flood Warning 86, NWS Las Vegas, NV

September 13, 2011Clark County, Nevada

NWS Las Vegas, NV issued this flash flood warning at Sep 13, 2011, 7:42 AM PDT for Clark County, Nevada. It was in force for 2 hr. 2 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 13, 2011, 7:42 AM PDT (14:42 UTC)
Expired
Sep 13, 2011, 9:45 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), 59 km from the middle of the area, began a volume at 14:43 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 13, 8:00 AM PDTFLASH FLOOD5 E Downtown Las Vegas, NVA WEATHER SPOTTER REPORTED THAT 12 TO 14 INCHES OF WATER WAS FLOWING ACROSS THE INTERSECTION OF NELLIS BOULEVARD AND STEWART AVENUE. BOTH ROADS WERE COVERED WITH WATER A QUARTER-MILE IN EACH DIRECTION.
Sep 13, 8:09 AM PDTFLASH FLOOD4 Ne Downtown Las Vegas, NVA SWIFT WATER RESCUE WAS REPORTED BY THE CLARK COUNTY FIRE DEPARTMENT AT THE INTERSECTION OF CHEYENNE AVENUE AND LAS VEGAS BOULEVARD.

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, 2.7 hours before the alert went out and 47 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 2011-09-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 239 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 2011-09-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 75 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
239 J/kg
Mixed-layer CIN
-98 J/kg
Mixed-layer LCL
1707 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
75 m²/s²
0-3 km storm-relative helicity
136 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

379 
WGUS55 KVEF 131442
FFWVEF
NVC003-131645-
/O.NEW.KVEF.FF.W.0086.110913T1442Z-110913T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE LAS VEGAS NV
742 AM PDT TUE SEP 13 2011

THE NATIONAL WEATHER SERVICE IN LAS VEGAS HAS ISSUED A

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

* UNTIL 945 AM PDT.

* AT 738 AM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM NEAR NELLIS AIR FORCE BASE...OR
  7 MILES EAST OF LAS VEGAS. THE STORM PRODUCING VERY HEAVY RAIN 
  WAS NEARLY STATIONARY. A GAGE ON THE LAS VEGAS WASH AT LAMB 
  BOULEVARD REPORTED OVER HALF AN INCH OF RAIN IN 15 MINUTES.

* LOCATIONS IMPACTED INCLUDE...
  NELLIS AIR FORCE BASE AND NORTH LAS VEGAS.

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 TWITTER #NWSVEGAS.

&&

LAT...LON 3629 11516 3628 11491 3610 11491 3611 11514

$$

MORGAN
4 follow-up statements
340 
WGUS75 KVEF 131516
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
816 AM PDT TUE SEP 13 2011

NVC003-131645-
/O.CON.KVEF.FF.W.0086.000000T0000Z-110913T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
816 AM PDT TUE SEP 13 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 945 AM PDT FOR
CENTRAL CLARK COUNTY...

AT 809 AM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE A THUNDERSTORM PRODUCING HEAVY RAIN OVER THE NORTHEAST PART 
OF THE LAS VEGAS VALLEY. AT 800 AM...A TRAINED SPOTTER REPORTED OVER 
A FOOT OF WATER FLOWING THROUGH THE INTERSECTION OF NELLIS AND 
STEWART. HEAVY RAIN WILL CONTINUE IN THE AREA...AND THE FLASH FLOOD 
WARNING REMAINS IN EFFECT.

LOCATIONS IMPACTED INCLUDE...
NORTH LAS VEGAS.

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 TWITTER #NWSVEGAS.

&&

LAT...LON 3629 11516 3628 11491 3610 11491 3611 11514

$$

MORGAN
883 
WGUS75 KVEF 131546
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
846 AM PDT TUE SEP 13 2011

NVC003-131645-
/O.CON.KVEF.FF.W.0086.000000T0000Z-110913T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
846 AM PDT TUE SEP 13 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 945 AM PDT FOR
CENTRAL CLARK COUNTY...

AT 841 AM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THAT RAIN WAS LETTING UP OVER THE NORTHEAST PART OF THE LAS VEGAS 
VALLEY. HOWEVER...FLOODING AND A SWIFT WATER RESCUE HAD ALREADY BEEN 
REPORTED IN THE AREA...AND WATER MAY STILL BE FLOWING. THUS...THE 
FLASH FLOOD WARNING REMAINS IN EFFECT.

LOCATIONS IMPACTED INCLUDE...
NELLIS AIR FORCE BASE AND NORTH LAS VEGAS.

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 TWITTER #NWSVEGAS.

&&

LAT...LON 3629 11516 3628 11491 3610 11491 3611 11514

$$

MORGAN
783 
WGUS75 KVEF 131614
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
914 AM PDT TUE SEP 13 2011

NVC003-131645-
/O.CON.KVEF.FF.W.0086.000000T0000Z-110913T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
914 AM PDT TUE SEP 13 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 945 AM PDT FOR
CENTRAL CLARK COUNTY...

AT 907 AM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE LIGHT RAIN IN THE NORTHEAST LAS VEGAS VALLEY. FLOODING AND 
A SWIFT WATER RESCUE HAVE ALREADY OCCURRED...AND ALTHOUGH RAIN HAS 
LET UP SIGNIFICANTLY...THE FLASH FLOOD WARNING WILL REMAIN IN EFFECT 
UNTIL 945 AM AS WATER IS LIKELY STILL FLOWING.

LOCATIONS IMPACTED INCLUDE...
NELLIS AIR FORCE BASE AND NORTH LAS VEGAS.

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 TWITTER #NWSVEGAS.

&&

LAT...LON 3629 11516 3628 11491 3610 11491 3611 11514

$$

MORGAN
652 
WGUS75 KVEF 131637
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
937 AM PDT TUE SEP 13 2011

NVC003-131646-
/O.EXP.KVEF.FF.W.0086.000000T0000Z-110913T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CLARK NV-
937 AM PDT TUE SEP 13 2011

...THE FLASH FLOOD WARNING WILL EXPIRE AT 945 AM PDT FOR CENTRAL
CLARK COUNTY...

AT 935 AM PDT...RADAR INDICATED ONLY LIGHT RAIN REMAINING OVER THE 
NORTHEAST PART OF THE LAS VEGAS VALLEY. FLOODING HAS LIKELY SUBSIDED 
IN THE AREA...AND THE FLASH FLOOD WARNING WILL BE ALLOWED TO EXPIRE 
AT 945 AM.

LAT...LON 3629 11516 3628 11491 3610 11491 3611 11514

$$

MORGAN

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 13, 3:31 AM PDTAreal Flood AdvisoryVEFClark119 min
Sep 13, 3:36 AM PDTFlash Flood WatchVEFClark15 hr
Sep 13, 5:46 AM PDTAreal Flood AdvisoryVEFClark119 min
Sep 13, 6:31 AM PDTFlash Flood WarningVEFClark86 min
Sep 13, 8:01 AM PDTFlash Flood WarningVEFClark119 min
Sep 13, 8:23 AM PDTFlash Flood WarningVEFClark112 min

Nearby

Flash Flood Warnings in Nevada, 2011Every flash flood warning in 2011

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.