Arizona, 1999

Flash Flood and Hail in Arizona, August 31, 1999

August 31, 1999 · NWS TWC · 4 events in 1 county or zone

2 thunderstorm wind, 1 hail, 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

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The toll

Deaths
0
Injuries
0
Property damage
$50,000
Crop damage
None recorded
Events
4

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.

The radar

The Tucson radar (KEMX), 33 km away, was scanning. The volume nearest the first event began at 21:33 UTC.

Open the radar archive at this moment

Event by event

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

Thunderstorm Wind, Pima

When
August 31, 2:35 PM MST to 2:55 PM MST
Where
Pima County, Green Vly to 6 mi N of Green Vly
Measured
50 kt (58 mph)
Reported by
TRAINED SPOTTER
Coordinates
31.820, -110.970

Green Valley experienced high winds and 0.5" hail from a passing thunderstorm.

Hail, Pima

When
August 31, 6:40 PM MST
Where
Pima County, 10 mi NE of Tucson
Measured
1 in hail
Reported by
NEWSPAPER
Coordinates
32.330, -110.820

Thunderstorm Wind, Pima

When
August 31, 7:05 PM MST to 7:35 PM MST
Where
Pima County, Tucson to 10 mi N of Tucson
Measured
55 kt (63 mph)
Property damage
$50,000
Reported by
NWS EMPLOYEE(OFF DUTY)
Coordinates
32.330, -110.820

Flash Flood, Pima

When
August 31, 7:15 PM MST
Where
Pima County, 7 mi NE of Tucson
Reported by
NEWSPAPER
Coordinates
32.097, -111.790 (the zone’s center; the record gives no point)

A thunderstorm moving through the Tucson Metro area produced two wind gusts of 55 knots. The first was reported from the East side of town where three power poles were knocked over and a roof was blown off of a house. The second was reported at the University of Arizona campus with no known damage. Tucson's East side also experienced flash flooding in which twelve people, including an eleven year old boy, needed to be rescued.

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.
Hail
Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
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 1999Every state in 1999This day in weather historyWarnings in Arizona, August 1999

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: 5719685, 5719686, 5719687, 5719688.