Flash Flood, Suffolk
- When
- August 11, 8:52 AM EST to 1:00 PM EST
- Where
- Suffolk County, Deer Park
- Reported by
- TRAINED SPOTTER
- Coordinates
- 40.941, -72.685 (the zone’s center; the record gives no point)
Flash Flood in New York, August 11, 1999
Clusters of thunderstorms formed along a warm front. As they moved very slowly east, they produced torrential rain that caused serious widespread flooding of low-lying and poor drainage areas from Deer Park to Manorville.
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
The toll
- Deaths
- 0
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 1
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 OKX wrote it up.
Clusters of thunderstorms formed along a warm front. As they moved very slowly east, they produced torrential rain that caused serious widespread flooding of low-lying and poor drainage areas from Deer Park to Manorville. Rainfall rates estimated from 1 to 2 inches per hour for up to 3 hours caused rainfall amounts from 3 to 5 inches mainly in the following areas: from Deer Park to Hauppauge, from Holtsville to Manorville and the Shirley-Mastic Area.Flooding caused many roads to close across Western and Central Suffolk County. Water rapidly accumulated up to 4 feet in many low-lying and poor drainage areas that "swept" cars away and trapped people in their vehicles.Here are selected rainfall amounts:East Patchogue: 4.40 inchesNWS Upton: 4.39 inchesSouth Manor: 4.25 inchesMedford: 4.18 inchesNesconset: 3.60 inchesHolbrook: 3.48 inchesRonkonkoma: 3.40 inches.
The radar
The national radar mosaic for the moment the first event began.
Event by event
1 flash flood. Local standard time, as filed.
What these are
- 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
- Tornado in Utah, August 11, 1999
- Hail and Damaging Wind in Kansas, August 11 to 26, 1999
- Hail and Damaging Wind in South Dakota, August 11, 1999
- Hail in Colorado, August 11, 1999
- Damaging Winds in Missouri, August 11, 1999
- Hail and Damaging Winds in Virginia, August 11, 1999
- Tornado in North Dakota, August 11, 1999
- Tornado in Wyoming, August 11, 1999
- Hail in Colorado, August 11, 1999
- Hail and Damaging Winds in Wyoming, August 11, 1999
- Hail and Lightning Strike in South Dakota, August 11, 1999
- Hail and Damaging Winds in North Carolina, August 11, 1999
More
Every storm in New York in 1999Every state in 1999This day in weather historyWarnings in New York, 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: 5717764.