Flash Flooding and Flooding in New York, June 17, 2001

On Sunday, June 17th, abundant moisture from the remnants of tropical storm Allison, combined with a cold front approaching from the west, produced extremely heavy rainfall across much of southeast New York during the early morning hours. Rainfall rates of up to 3 inches per hour produced widespread street and highway flooding, in addition to some flash flooding of small streams. Some rivers approached or even slightly exceeded flood stage during this heavy rain event.Heavy rain first affected portions of Rockland and Westchester Counties between 3:30 AM and 6 AM EDT. The area of heavy rain then slowly shifted east, across New York City around mid morning through midday, Nassau and western Suffolk Counties from late morning through early afternoon, and across central and eastern Suffolk County during the early to mid afternoon hours. In Rockland County, the Mahwah River at Suffern crested at 3.79 feet at 10:15 AM EDT, remaining just below its' flood stage of 4.0 feet. However, widespread flooding of streets occurred during the morning hours in Rockland County, closing several major roads which became impassable due to the excessive rainfall. Several houses were also evacuated due to flooding conditions, particularly near Valley Cottage.Excessive rainfall also led to severe flooding conditions across portions of Westchester County. In Greenburgh, 23 residential structures experienced basement flooding, causing thousands of dollars of property damage in the Babbitt Court area. In Ossining, the Sparta Brook overflowed its' banks around 5 AM EDT, washing away a backyard and flooding an adjoining basement and garage. Flooding also was reported in Mt. Kisco, particularly near Shoppers Park, where several stores reported damage from the flooding. Damage to several municipal buildings was also reported in other portions of downtown Mt. Kisco. There were also numerous reports of street and highway flooding in the New York City area, as well as Nassau and Suffolk Counties on Long Island, which led to several major road and highway closings.Here are some rainfall totals for this event:In Rockland County: 1.65 inches at Suffern.In Westchester County: From 2.69 inches at Westchester County Airport in White Plains, to 5.73 inches in Granite Springs.In the New York City area: From 1.37 inches in Brooklyn, to 2.36 inches at John F. Kennedy International Airport in Queens. In addition, a daily record amount of 1.55 inches occurred at Central Park.In Nassau County: From 2.51 inches at Wantagh, to 5 inches at Lido Beach.In Suffolk County: From 2.27 inches at Copiague, to 4.35 inches at Patchogue.