Arizona, 2003

Flash Flood and Damaging Wind in Arizona, August 20, 2003

August 20, 2003 · NWS PSR · 2 events in 1 county or zone

1 thunderstorm wind, 1 flash flood, as filed by the National Weather Service.

Where it happened

Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

Open the live radar over this ground

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
2

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What forecasters said that day

The local office's own words before the first event, 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 the first event at Aug 20, 1:57 PM MST, 3 minutes earlier.

Area forecast discussion, Aug 20, 1:57 PM MST, 3 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 20 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 radar

The Yuma radar (KYUX), 44 km away, was scanning. The volume nearest the first event began at 21:02 UTC.

Open the radar archive at this moment

Event by event

1 thunderstorm wind, 1 flash flood. Local standard time, as filed.

Thunderstorm Wind, Yuma

When
August 20, 2:00 PM MST to 2:10 PM MST
Where
Yuma County, 20 mi E of Yuma
Measured
60 kt (69 mph) estimated gust
Reported by
TRAINED SPOTTER
Coordinates
32.717, -114.267

Large 40 foot tree blown down.

Flash Flood, Yuma

When
August 20, 3:15 PM MST to 4:05 PM MST
Where
Yuma County, 5 mi E of Yuma
Reported by
TRAINED SPOTTER
Coordinates
32.769, -113.906 (the zone’s center; the record gives no point)

Several roads closed in the Foothills area after very heavy rains. One spotter received 1.21 inches in about an hour.

What these are

Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Flash Flood
Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Arizona in 2003Every state in 2003This day in weather historyWarnings in Arizona, August 2003

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5374727, 5374728.