Alert archive / Arizona / Flash Flood Warnings in 2012

Flash Flood Warning 40, NWS Phoenix, AZ

August 18, 2012Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 18, 2012, 6:49 PM MST for Maricopa County, Arizona. It was in force for 56 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: Aug 18, 2012, 6:49 PM MST (01:49 UTC)
Expired: Aug 18, 2012, 7:45 PM MST
In force: 56 min
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Flood severity: None

County Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 103 km from the middle of the area, began a volume at 01:48 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, 1.8 hours before the alert went out and 72 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: 944 J/kg
Mixed-layer CIN: -83 J/kg
Mixed-layer LCL: 1674 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: 20 m²/s²
0-3 km storm-relative helicity: 57 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.

903 
WGUS55 KPSR 190149
FFWPSR
AZC013-190245-
/O.NEW.KPSR.FF.W.0040.120819T0149Z-120819T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
649 PM MST SAT AUG 18 2012

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTH CENTRAL MARICOPA COUNTY IN SOUTH CENTRAL ARIZONA...
  THIS INCLUDES WITTMANN...CIRCLE CITY...

* UNTIL 745 PM MST

* AT 639 PM MST...VERY HEAVY THUNDERSTORM RAINS WERE DEVELOPING NEAR 
MORRISTOWN AND CIRCLE CITY. THUNDERSTORMS WERE MOVING VERY SLOWLY 
SOUTH...AND COULD QUICKLY PRODUCE FLOOD OR FLASH FLOODING IN 
NORMALLY DRY WASHES IN THE AREA. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO MORRISTOWN

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WARNING MEANS THAT PEOPLE ALONG THE BANKS OF WASHES AND
CREEKS SHOULD MOVE TO HIGHER GROUND IMMEDIATELY. NORMALLY DRY WASHES
AND STREAMS WILL SUDDENLY HAVE RUNNING WATER AND MAKE UNBRIDGED
CROSSINGS IMPASSABLE. STREETS...UNDERPASSES...AND LOW SPOTS WILL
BECOME INUNDATED MAKING DRIVING HAZARDOUS IN THE WARNED AREA.

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 3396 11254 3384 11243 3370 11255 3380 11271

$$

HV

1 follow-up statement

242 
WGUS75 KPSR 190240
FFSPSR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
740 PM MST SAT AUG 18 2012

AZC013-190246-
/O.EXP.KPSR.FF.W.0040.000000T0000Z-120819T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MARICOPA AZ-
740 PM MST SAT AUG 18 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 745 PM MST FOR NORTH
CENTRAL MARICOPA COUNTY...

THE FLASH FLOOD WARNING ISSUED EARLIER FOR AREAS AROUND MORRISTOWN 
AND CIRCLE CITY WILL EXPIRE AT 745 PM. VERY HEAVY THUNDERSTORM RAIN  
FELL...BUT MAINLY IN THE DESERTS OUTSIDE OF MORRISTOWN AND CIRCLE 
CITY. IT WAS LIKELY THAT FLASH FLOODING IN DRY WASHES OCCURRED... 
BUT THERE WERE NO REPORTS TO SUBSTANTIATE WEATHER RADAR SIGNATURES.

LAT...LON 3396 11254 3384 11243 3370 11255 3380 11271

$$

HV

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 5:09 PM MST	Flash Flood Warning	PSR	Maricopa	81 min
Aug 18, 6:42 PM MST	Areal Flood Advisory	PSR	Maricopa	68 min
Aug 18, 7:14 PM MST	Special Weather Statement	PSR		76 min
Aug 19, 1:41 PM MST	Areal Flood Advisory	PSR	Gila, Maricopa, Pinal	2 hr
Aug 19, 4:38 PM MST	Areal Flood Advisory	PSR	Gila	112 min
Aug 19, 4:50 PM MST	Special Weather Statement	PSR	Gila	70 min
Aug 19, 4:52 PM MST	Flash Flood Warning	PSR	Gila	83 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.