NYC Gets Two Months Worth of Rain in One Day

August 15, 2011; 3:23 PM
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This radar image showing 24-hour precipitation as of 4:00 a.m. EDT Monday shows a bulls-eye of rainfall of more than 4.0 inches from eastern Maryland to Connecticut.

"nearly twice the normal monthly rainfall was delivered (to New York City) in one day"

Extreme rain resulted in flooding across the Northeast on Sunday. Records were smashed, including an all-time record rainfall at the JFK International Airport in NYC.

The New York City JFK Airport set the wettest day on record with 7.80 inches on Sunday. This smashed the all-time daily rainfall record of 6.27 inches on June 30, 1984. The old daily rainfall record was 0.96 of an inch of rain set in 2008.

The normal rainfall for the month of August at the JFK Airport is 3.68 inches, so nearly twice the normal monthly rainfall was delivered in one day.

Cars submerged under floodwaters in Staten Island, New York City on Sunday August 14, 2011. Photo courtesy of Facebook fan Mike B.

The excessive rainfall amounts in the Northeast with this storm are more on par with the rain from a tropical storm or a hurricane. Significant flooding resulted in many communities. Many roads were closed and swift water rescues performed as flood waters rose quickly.

Topping the list of excessive rainfall amounts, Lido Beach, N.Y., got an astounding 10.87 inches of rain.

Newark, N.J., was deluged by 6.40 inches of rain. This broke the old rainfall record of 1.11 inches set in 1999.

Philadelphia got 4.84 inches of rain on Sunday, shattering the old daily rainfall record of 1.77 inches set in 1977. The inundating rain surpasses the normal monthly rainfall of 3.50 inches.

More daily rain records set on Sunday:

-New York City (LaGuardia Airport): 6.60 inches; old record 3.51 inches/2005

-New York City (Central Park): 5.81 inches; old record 3.10 inches/2005

-Islip, N.Y.: 5.31 inches; old record 1.04 inches/1994

-Trenton, N.J.: 4.66 inches; old record 3.40 inches/1999

-Bridgeport, Conn.: 2.75 inches; old record 1.79 inches/1999

Contributing Factors to the Flood Situation

The main reason for the flooding is that the storm system that has been unleashing the rainfall moved very slowly across the mid-Atlantic, allowing torrential downpours to keep moving across the same areas repeatedly.

The storm system was able to tap into moisture from both the Gulf of Mexico and the Atlantic.

Unfortunately, the storm system will skirt slowly up the Northeast Coast through tonight, allowing more heavy rain to pour down and aggravate flooding.

Another factor of the flooding is the fact that there has been a very dry pattern set up across the Northeast this summer. When there has been a dry pattern in place, water is not able to penetrate the parched soil as easily.

The U.S. Drought Monitor release on Aug. 9, 2011, shows abnormally dry to moderate drought conditions across portions of the Northeast. The dry conditions are likely a contributing factor to some of the flooding.

The total of 7.80 inches of rain that fell at the JFK International Airport is almost as much rain that fell during the months of May, June and July combined (7.96 inches).


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