Alert archive / Arizona / Flash Flood Warnings in 2008

Flash Flood Warning 21, NWS Phoenix, AZ

July 21, 2008Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 21, 2008, 7:40 PM MST for Maricopa County, Arizona. It was in force for 68 min. 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 21, 2008, 7:40 PM MST (02:40 UTC)
Expired: Jul 21, 2008, 8:48 PM MST
In force: 68 min
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Flood severity: None

County Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 24 km from the middle of the area, began a volume at 02:40 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

Phoenix, AZ (KPSR), launched 00:00Z, 2.7 hours before the alert went out and 15 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: 669 J/kg
Mixed-layer CIN: -70 J/kg
Mixed-layer LCL: 2090 m above ground
0-6 km bulk shear: 5 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: 25 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.

000 
WGUS55 KPSR 220240
FFWPSR
AZC013-220345-
/O.NEW.KPSR.FF.W.0021.080722T0240Z-080722T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
740 PM MST MON JUL 21 2008

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EAST CENTRAL MARICOPA COUNTY IN SOUTH CENTRAL ARIZONA...THIS 
  INCLUDES THE CITIES OF...TEMPE...MESA...GILBERT...FOUNTAIN 
  AND CHANDLER. 

* UNTIL 845 PM MST

* AT 732 PM MST...FLASH FLOODING WAS LIKELY FROM THUNDERSTORMS
  OVER THE WARNED AREA. THUNDERSTORMS WILL CONTINUE TO DEVELOP
  IN THE EAST VALLEY WITH URBAN FLOODING.

* THE STORM PRODUCING FLASH FLOODING WILL OTHERWISE REMAIN OVER
  MAINLY RURAL AREAS OF THE INDICATED COUNTY.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

IN HILLY TERRAIN THERE ARE HUNDREDS OF LOW WATER CROSSINGS WHICH ARE
POTENTIALLY DANGEROUS IN HEAVY RAIN. DO NOT ATTEMPT TO TRAVEL ACROSS
FLOODED ROADS. FIND ALTERNATE ROUTES. IT TAKES ONLY A FEW INCHES OF
SWIFTLY FLOWING WATER TO CARRY VEHICLES AWAY.

LAT...LON 3363 11197 3360 11159 3324 11160 3325 11197

$$

HV

2 follow-up statements

000 
WGUS75 KPSR 220348
FFSPSR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
848 PM MST TUE JUL 21 2008

AZC013-220345-
/O.CON.KPSR.FF.W.0021.000000T0000Z-080722T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MARICOPA AZ-
848 PM MST TUE JUL 21 2008

...A FLASH FLOOD WARNING FOR THE PHOENIX EAST VALLEY...IN EAST 
CENTRAL MARICOPA COUNTY...WAS ALLOWED TO EXPIRE AT 845 PM...

AT 835 PM MST...THUNDERSTORM PRODUCING FLASH FLOODING HAD ENDED 
OVER MESA AND VICINITY. 

THERE WERE NUMEROUS REPORTS OF FLOODED STREETS AND ROADWAYS...
AS WELL AS PONDED OF WATER. 

AN URBAN AND SMALL STREAM FLOOD ADVISORY REMAINS IN EFFECT UNTIL 
930 PM.


LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO PARADISE
VALLEY AND FOUNTAIN HILLS

LAT...LON 3363 11197 3360 11159 3324 11160 3325 11197

$$

HV

000 
WGUS75 KPSR 220354
FFSPSR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
854 PM MST TUE JUL 21 2008

AZC013-220400-
/O.EXP.KPSR.FF.W.0021.000000T0000Z-080722T0348Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MARICOPA AZ-
854 PM MST TUE JUL 21 2008

...THE FLASH FLOOD WARNING FOR THE PHOENIX EAST VALLEY...IN EAST 
CENTRAL MARICOPA COUNTY...EXPIRED AT 845 PM...

THUNDERSTORM PRODUCING FLASH FLOODS IN MESA HAVE ENDED. HOWEVER A 
SLIGHT CHANCE OF THUNDERSTORMS...SOME WITH HEAVY RAIN...WILL REMAIN 
OVERNIGHT.

LAT...LON 3363 11197 3360 11159 3324 11160 3325 11197

$$

HV

The office that day

Everything else NWS Phoenix, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 21, 5:20 PM MST	Areal Flood Advisory	PSR	Gila	115 min
Jul 21, 5:31 PM MST	Flash Flood Warning	PSR	Gila	59 min
Jul 21, 7:35 PM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	115 min
Jul 21, 7:38 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	37 min
Jul 22, 1:14 PM MST	Areal Flood Advisory	PSR	Gila	3 hr

Nearby

Flash Flood Warnings in Arizona, 2008 Every flash flood warning in 2008

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.