Long Island rainfall is 200-year weather event, experts say

Vehicles are submerged on a flooded section of Sunrise Highway, in East Islip, N.Y., on New York's Long Island.

MELVILLE, N.Y. — A historic weather event dumped double-digit amounts of rainfall across parts of Long Island early Wednesday, flooding everything from roadways to basements and delaying all modes of travel.

The epic rainfall — the National Weather Service’s Upton office said 13.27 inches poured down between 11 p.m. Tuesday and 10:30 a.m. Wednesday — overwhelmed virtually every major roadway in Nassau and Suffolk counties at some point.

The state Department of Transportation website listed more than a dozen flooded roadways, starting before 5 a.m. and lasting through the afternoon hours.

As flooding forced closures into the afternoon hours on portions of the Long Island Expressway in both counties, the Wantagh State Parkway in Hempstead and Sunrise Highway in Suffolk, the Northeast Regional Climate Center said “rainfall of this magnitude is only expected to occur once in a 200-year period.”

One fatality in an early morning motor-vehicle accident on the LIE likely was related to the rain, Suffolk County police said. The fatal crash, on the westbound LIE in Melville, occurred just before 5 a.m. during the height of the rainstorm.

Gov. Andrew M. Cuomo dispatched emergency equipment and personnel to Long Island, and Suffolk County Executive Steve Bellone, who said the county received several reports of homes damaged by flooding, added that the rainfall was “historic.”

The 13.27 inches was recorded at Long Island MacArthur Airport in Ronkonkoma and set a state record for precipitation in a 24-hour period, the weather service said.

According to a preliminary report, that amount breaks the previous mark of 11.6 inches recorded on Aug. 27-28, 2011, in Tannersville, during what the service referred to as Hurricane/Tropical Storm Irene.

Also reporting double-digit rainfall in Suffolk County locations were a weather service employee and trained spotters, with 12.57 inches recorded in Holbrook; 11.50 in West Islip; 11.35 in Bay Shore. Nassau saw 7.84 inches in Wantagh, 6.81 inches in Merrick, 5.30 in Lido Beach.

The downpour also caused delays at area airports as well as delays and cancellations on the Long Island Rail Road.

The Metropolitan Transportation Authority advised customers in a release to expect some cancellations and minor delays during the evening’s rush hour due to “lingering weather-related issues.”

On the roads during the day, drivers encountered flooding almost everywhere.

Speaking from a fire house in North Babylon, where 50 motorists had been stranded, Bellone said, “I’ve never seen this level of flooding in my entire time in government.” He said that there had been a flash flood warning, but “no one predicted anything like this.”

Town of Islip Supervisor Tom Croci declared a state of emergency, meaning officials can circumvent some policies to more quickly to deal with flood damage. He also urged residents to stay off all roadways.

Nassau County Executive Edward Mangano said that there was “localized” flooding throughout the county, particularly on the South Shore. But, he said, all county roadways are open, and state roadways, including highways, are open, although some may have lane closures.

“We are urging motorists to use caution because of pooling of water,” Mangano said, noting that there had been several accidents, but no major injuries in Nassau that he was aware of.

In a flood advisory, which lasted until late morning, the weather service warned motorists not to drive their vehicles into areas “where water covers the roadway,” adding that even “one foot of flowing water is powerful enough to sweep vehicles off the road.”

Nearly every major roadway in Nassau and Suffolk counties reported full to partial closures because of flooding as early as 4:30 a.m. and until past noon, according to the state Department of Transportation.

The most seriously affected areas included the westbound Long Island Expressway from exits 49 through 50, where the fatal accident took place, and the Southern State Parkway eastbound, between exits 40 and 43N.

In many cases, all lanes were closed for several hours, with traffic backed up for miles.

Parkway closures lasted until early afternoon, according to State Police.

Fewer than 1,000 customers had storm-related power outages as of early afternoon, according to PSEG Long Island, down from an earlier 5,500.

The heavy rainfall also had an impact on water quality at local beaches, affecting bathing and shellfish harvesting.

Suffolk County Health Department issued an advisory against bathing at 66 beaches until 7 p.m. Thursday as sampling is conducted because of the potential of elevated bacteria levels.

The Department of Environmental Conservation also closed shellfish harvesting in most towns in Nassau and Suffolk counties until officials determine hazardous conditions no longer exist.