Alert archive / Arizona / Flash Flood Warnings in 2003

Flash Flood Warning 6, NWS Phoenix, AZ

August 20, 2003Yuma County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 20, 2003, 2:10 PM MST for Yuma County, Arizona. It was in force for 50 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 20, 2003, 2:10 PM MST (21:10 UTC)
Expired: Aug 20, 2003, 3:00 PM MST
In force: 50 min
Issued by: NWS Phoenix, AZ
Area: Counties, with a storm outline in the text

County Yuma County, AZ

The radar

The Yuma radar (KYUX), 23 km from the middle of the area, began a volume at 21:12 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this flash flood warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Yuma Intl Airpor, AZ (KYUM), launched 12:00Z, 9.2 hours before the alert went out and 13 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: 4 J/kg
Mixed-layer CIN: -263 J/kg
Mixed-layer LCL: 1937 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 44 m²/s²
0-3 km storm-relative helicity: 33 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 202111
FFWPSR
AZC027-202300-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
210 PM MST WED AUG 20 2003

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHWEST YUMA COUNTY IN SOUTHWEST ARIZONA

* UNTIL 400 PM MST

* AT 210 PM MST...WEATHER SERVICE DOPPLER RADAR INDICATED VERY HEAVY 
RAIN EXTENDING FROM THE INTERNATIONAL BORDER SOUTH OF YUMA NORTHEAST 
TO NEAR FORTUNA FOOTHILLS. RAINFALLS IN EXCESS OF 1 INCH PER HOUR... 
AND RAINFALL RATES IN EXCESS OF 2 INCHES PER HOUR...WERE DETECTED BY 
YUMA DOPPLER RADAR BETWEEN 1 AND 2 PM. 

* CITIES AND LOCATIONS IN THE WARNED AREA INCLUDE FORTUNA 
FOOTHILLS...LIGURTA...EAST PORTIONS OF YUMA...AND THE GILA AND 
LAGUNA MOUNTAINS...ALONG INTERSTATE 8 BETWEEN YUMA AND LIGURTA...AND 
STATE ROUTE 95.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS OCCURRING OR IS 
IMMINENT. MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES. DO NOT 
ATTEMPT TO CROSS BRIDGES...DIPS...OR OTHER LOW SPOTS IF WATER COVERS 
THE ROADWAY. NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL 
ONE...ON FOOT. TO ESCAPE RISING WATER MOVE UP TO HIGHER GROUND.

TO REPORT SEVERE WEATHER HAVE THE NEAREST LAW ENFORCEMENT AGENCY 
RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN 
PHOENIX.

LAT...LON 3244 11463 3236 11434 3277 11419 3286 11433
          3282 11449 3265 11466

$$

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Phoenix, AZ wrote its last area forecast discussion before this flash flood warning went out at Aug 20, 1:57 PM MST, 13 minutes earlier.

Area forecast discussion, Aug 20, 1:57 PM MST, 13 minutes before

AZZ020>028-CAZ030>033-202245-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION CORRECTION
WEATHER SERVICE PHOENIX AZ
1030 AM MST WED AUG 20 2003

.SYNOPSIS...
A WEAK LOW PRESSURE SYSTEM WILL MOVE NORTH ACROSS SOUTHERN
CALIFORNIA AND SOUTHWEST ARIZONA THIS AFTERNOON AND THIS EVENING.
THIS MEANS A CHANCE OF SHOWERS AND THUNDERSTORMS MAINLY OVER
SOUTHERN CALIFORNIA AND SOUTHWEST ARIZONA THIS AFTERNOON AND THIS
EVENING. HIGH PRESSURE ALOFT OVER NEW MEXICO WILL MOVE NORTH TO
COLORADO BY THURSDAY...AND STAY TO THE NORTH THROUGH MONDAY. THIS
MEANS A MOIST FLOW OF AIR FROM THE EAST WITH A CHANCE OF AFTERNOON
AND EVENING SHOWERS AND THUNDERSTORMS THROUGH EARLY NEXT WEEK.

.DISCUSSION...
LATE MORNING TEMPERATURES WERE GENERALLY 9 TO 14 DEGREES WARMER IN
THE PHOENIX AREA AND NORTH PORTION OF THE WEST CENTRAL DESERT AREAS
COMPARED WITH THE SAME TIME YESTERDAY. THIS WAS DUE TO SUNNY SKIES
THIS MORNING WITH THE LACK OF CLOUD COVER THERE WAS YESTERDAY.
OTHERWISE...TEMPERATURES WERE GENERALLY 4 OR 4 DEGREES WARMER IN THE
SOUTH PORTION OF SOUTH-CENTRAL ARIZONA...AND 2 OR 3 DEGREES COOLER
IN FAR SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA. THE AIRMASS IS
STILL MOIST AND UNSTABLE. THUS...WITH A WEAK LOW PRESSURE SYSTEM
MOVING NORTH ACROSS THE AREA...MAINLY SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA...EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP
PARTICULARLY IN THOSE AREAS THIS AFTERNOON. HOWEVER...THERE IS A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS DEVELOPING IN THE
SOUTH-CENTRAL ARIZONA DESERT AREAS INCLUDING PHOENIX AS WELL AND
PLAN ON UPDATING FOR THIS. ISOLATED THUNDERSTORMS WERE ALREADY
DEVELOPING IN JOSHUA TREE NATIONAL PARK LATE THIS MORNING AND
CONSIDERING A FLASH FLOOD WATCH FOR THIS AREA FOR THIS AFTERNOON AND
EVENING. HIGH PRESSURE ALOFT CENTERED OVER NEW MEXICO WILL MOVE
NORTH TO COLORADO BY THURSDAY...AND STAY TO THE NORTH THROUGH
MONDAY. THIS MEANS A MOIST FLOW OF AIR FROM THE EAST WITH A CHANCE
OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS THROUGH EARLY
NEXT WEEK. WEAK LOW PRESSURE SYSTEMS IN THIS FLOW ARE EXPECTED TO
ENHANCE THE CHANCE OF SHOWERS AND THUNDERSTORMS AT TIMES WHICH IS
EXPECTED TO BE THE CASE THURSDAY NIGHT INTO FRIDAY MORNING.

ELLIS

.PSR...NONE.

CORRECTED EXPIRATION TIME

Hazardous weather outlook, Aug 20, 12:40 PM MST, 1 hour 30 minutes before

AZZ020>028-CAZ030>033-210100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1240 PM MST WED AUG 20 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST AND
SOUTH-CENTRAL ARIZONA...AND SOUTHEAST CALIFORNIA.

.DAY ONE...TODAY

A FLASH FLOOD WATCH IS IN EFFECT FOR SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA UNTIL 9 PM THIS EVENING. PLEASE SEE THE FLASH FLOOD WATCH
PRODUCT PHXHWOPSR OR WMO HEADER WGUS65 KPSR FFAPSR.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.INSTRUCTIONS TO SPOTTERS...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

ELLIS

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 20, 1:27 PM MST	Severe Thunderstorm Warning	PSR	Yuma	63 min

Nearby

Flash Flood Warnings in Arizona, 2003 Every flash flood warning in 2003

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.