Flash Flooding and Hail in Oklahoma, May 21, 1999

Name: Flash Flooding and Hail in Oklahoma, May 21, 1999
Start: 1999-05-21T02:00
End: 1999-05-21T08:00
Location: Oklahoma

May 21, 1999 · NWS TSA · 7 events in 6 counties and zones

Summary of events for May 21 1999:A line of thunderstorms moved east-southeast across eastern Oklahoma early on the morning of May 21. These storms gradually weakened as they moved along, producing reports of marginally severe wind.

Where it happened

Every event with a place to put it; 2 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: $200
Crop damage: None recorded
Events: 7

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 happened

The episode as NWS TSA wrote it up.

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

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

Thunderstorm Wind, Osage

When: May 21, 2:00 AM CST
Where: Osage County, 3 mi N of Sand Spgs
Measured: 52 kt (60 mph)
Reported by: AMATEUR RADIO
Coordinates: 36.200, -96.120

Thunderstorm Wind, Tulsa

When: May 21, 2:10 AM CST
Where: Tulsa County, 4 mi S of Tulsa
Measured: 52 kt (60 mph)
Property damage: $100
Reported by: AMATEUR RADIO
Coordinates: 36.100, -95.950

A spotter at 51st and Riverside in Tulsa estimated winds to gust as high as 60 miles an hour. A large tree was blown down at 39th and Riverside, partially blocking the roadway.

Thunderstorm Wind, Wagoner

When: May 21, 2:30 AM CST
Where: Wagoner County, 2 mi NW of Oneta
Property damage: $100
Reported by: UNKNOWN
Coordinates: 36.030, -95.750

Large tree branches were blown down.

Thunderstorm Wind, Cherokee

When: May 21, 3:20 AM CST
Where: Cherokee County, 8 mi N of Moodys
Measured: 61 kt (70 mph)
Reported by: UNKNOWN
Coordinates: 36.150, -94.950

Flash Flood, Wagoner

When: May 21, 5:00 AM CST to 6:00 AM CST
Where: Wagoner County, Coweta
Reported by: LAW ENFORCEMENT
Coordinates: 35.961, -95.521 (the zone’s center; the record gives no point)

Several city streets in Coweta were closed by high water.

Hail, Pittsburg

When: May 21, 6:45 AM CST
Where: Pittsburg County, Arpelar
Measured: 0.75 in hail
Reported by: GENERAL PUBLIC
Coordinates: 34.930, -95.970

Flash Flood, Le Flore

When: May 21, 7:30 AM CST to 8:00 AM CST
Where: Le Flore County, Arkoma
Reported by: UNKNOWN
Coordinates: 34.900, -94.703 (the zone’s center; the record gives no point)

There was street flooding in Arkoma.

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.
Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.

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

The same day elsewhere

Every storm in Oklahoma in 1999 Every state in 1999 This day in weather history Warnings in Oklahoma, May 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: 5700267, 5700266, 5700268, 5700269, 5700270, 5700271, 5700272.