Alert archive / Arizona / Flash Flood Warnings in 2012

Flash Flood Warning 44, NWS Phoenix, AZ

August 20, 2012Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 20, 2012, 7:21 PM MST for Maricopa County, Arizona. It was in force for 114 min. 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 20, 2012, 7:21 PM MST (02:21 UTC)
Expired: Aug 20, 2012, 9:15 PM MST
In force: 114 min
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Flood severity: None

County Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 14 km from the middle of the area, began a volume at 02:24 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
Aug 20, 7:35 PM MST	HEAVY RAIN 1.25	6 E Mesa, AZ	RAINFALL OCCURRED IN 35 MINUTES.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 00:00Z, 2.4 hours before the alert went out and 22 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: 843 J/kg
Mixed-layer CIN: -56 J/kg
Mixed-layer LCL: 2302 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 8 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.

936 
WGUS55 KPSR 210221
FFWPSR
AZC013-210415-
/O.NEW.KPSR.FF.W.0044.120821T0221Z-120821T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
721 PM MST MON AUG 20 2012

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EAST CENTRAL MARICOPA COUNTY IN SOUTH CENTRAL ARIZONA...
  THIS INCLUDES EAST MESA...MESA...GILBERT...

* UNTIL 915 PM MST

* AT 713 PM MST...THUNDERSTORMS WITH EXTREMELY HEAVY RAIN WAS 
   DEVELOPING IN MESA...BETWEEN FALCON FIELD AND THE SUPERSTITION 
   SPRINGS MALL. RAINFALL WAS HEAVY ENOUGH TO CAUSE FLOOD OR FLASH
   FLOODING IN DRAINAGE AREAS AND CITY STREETS.  

* LOCATIONS IN THE WARNING INCLUDE NEARBY AREAS IN MESA...INCLUDING
  DOWNTOWN. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF NORMALLY
DRY WASHES AND CREEKS...STREETS AND UNDERPASSES...AND DETENTION
BASINS AFFECTING SOME COMMUNITY PARKS. UNBRIDGED CROSSINGS WILL BE
ESPECIALLY DANGEROUS.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF NORMALLY
DRY WASHES AND CREEKS...ROADS...AND LOW LYING SPOTS. UNBRIDGED
CROSSINGS WILL BE ESPECIALLY DANGEROUS.

&&

LAT...LON 3346 11181 3346 11162 3332 11162 3332 11179

$$

HV

1 follow-up statement

762 
WGUS75 KPSR 210414
FFSPSR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
914 PM MST MON AUG 20 2012

AZC013-210421-
/O.EXP.KPSR.FF.W.0044.000000T0000Z-120821T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MARICOPA AZ-
914 PM MST MON AUG 20 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 915 PM MST FOR EAST CENTRAL
MARICOPA COUNTY...

RAINFALL HAS GENERALLY DIMINISHED ACROSS THE EAST MESA AREA THIS 
EVENING. ANY LINGERING SHOWERS THIS EVENING WILL PRODUCE RATHER 
LIGHT NEW RAINFALL ACCUMULATIONS. HOWEVER...EXPECT FLOODING IMPACTS 
OF PONDED AND STANDING WATER TO REMAIN ACROSS NEIGHBORHOOD STREETS 
AND INTERSECTIONS FOR THE NEXT FEW HOURS.

LAT...LON 3346 11181 3346 11162 3332 11162 3332 11179

$$

NOLTE

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 20, 5:05 PM MST	Special Weather Statement	PSR		55 min
Aug 20, 5:43 PM MST	Special Weather Statement	PSR	La Paz	47 min
Aug 20, 6:01 PM MST	Flash Flood Warning	PSR	La Paz	89 min
Aug 20, 6:42 PM MST	Special Weather Statement	PSR	Maricopa	33 min
Aug 20, 6:53 PM MST	Special Weather Statement	PSR		37 min
Aug 20, 6:57 PM MST	Areal Flood Advisory	PSR	Maricopa	62 min
Aug 20, 7:01 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	59 min
Aug 20, 7:11 PM MST	Blowing Dust Advisory	PSR		81 min
Aug 21, 2:17 PM MST	Special Weather Statement	PSR	Gila	43 min
Aug 21, 3:51 PM MST	Special Weather Statement	PSR	La Paz	39 min
Aug 21, 4:18 PM MST	Areal Flood Advisory	PSR	Gila	117 min
Aug 21, 4:42 PM MST	Areal Flood Advisory	PSR	La Paz	93 min

Nearby

Flash Flood Warnings in Arizona, 2012 Every 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.