Flash Flooding in New York, September 8, 1999

Name: Flash Flooding in New York, September 8, 1999
Start: 1999-09-08T07:15
End: 1999-09-08T15:00
Location: New York

September 8, 1999 · NWS OKX · 3 events in 3 counties and zones

A narrow band of slow-moving heavy showers and thunderstorms produced rainfall rates of at least 2 inches per hour, that caused significant street flooding. As heavy showers and thunderstorms moved slowly east, they produced rainfall rates of at least 2 inches per hour.

Where it happened

Every event with a place to put it; 3 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: None recorded
Crop damage: None recorded
Events: 3

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.

A narrow band of slow-moving heavy showers and thunderstorms produced rainfall rates of at least 2 inches per hour, that caused significant street flooding. Cars stalled as water ponded to 2 1/2 feet in about 20 minutes along parts of Sunrise Highway near Lindenhurst.As heavy showers and thunderstorms moved slowly east, they produced rainfall rates of at least 2 inches per hour. Aided by southeast winds, the heaviest rainfall occurred along the higher terrain of extreme southeast Orange County and extreme northwest Rockland County. In Rockland County, water accumulated up to 3 feet on Union and Stonehouse Roads in Spring Valley, where cars stalled. Several basements were flooded in the Pomona-Hillcrest-Monsey-Spring Valley corridor.This rainfall was associated with the remnants of tropical system Dennis, as it moved west of the area.

The radar

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

Open the radar archive at this moment

Event by event

3 flash flood. Local standard time, as filed.

Flash Flood, Suffolk

When: September 8, 7:15 AM EST to 7:45 AM EST
Where: Suffolk County, West Gilgo Beach
Reported by: NEWSPAPER
Coordinates: 40.941, -72.685 (the zone’s center; the record gives no point)

Flash Flood, Rockland

When: September 8, 3:00 PM EST
Where: Rockland County, Northwest Portion
Reported by: TRAINED SPOTTER
Coordinates: 41.152, -74.024 (the zone’s center; the record gives no point)

Flash Flood, Orange

When: September 8, 3:00 PM EST
Where: Orange County, Southeast Portion
Reported by: EMERGENCY MANAGER
Coordinates: 41.402, -74.306 (the zone’s center; the record gives no point)

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

Every storm in New York in 1999 Every state in 1999 This day in weather history Warnings in New York, September 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: 5722906, 5722907, 5722908.