News•August 13, 2014

10 Images Show & Explain the Northeast Flooding

By Andrea Thompson & Brian Kahn

Records fell along with the torrential rain that swamped parts of the East Coast from Baltimore up to Long Island from Tuesday through Wednesday morning. A series of storms parked themselves over certain parts of the region, dumping enough rain to inundate roads, parking lots, front lawns and backyards.

On Tuesday, Baltimore-Washington International Airport recorded 6.3 inches of rain, a record amount for the date. That's also the second-highest rainfall total in the books for that station on any day. The highest mark was set in August 1933 when a hurricane swept across the Chesapeake Bay area. Because rain fell so fast and hard, standing water quickly rose in a number of spots around the airport including the long-term parking lot.

The storms reserved their heaviest rains on Tuesday for areas south of Baltimore. In northern Anne Arundel County a stunning 10.32 inches fell.

On Wednesday, heavy rains moved from the Mid-Atlantic to the Northeast. Preliminary observations indicate that the 24-hour rainfall record for all of New York state was broken in the wee hours of Wednesday morning. According to the National Weather Service, a mind-boggling 13.26 inches had fallen by 9:30 a.m. ET at Islip McArthur Airport on Long Island. That includes a stretch where more than 5 inches fell in an hour and is 1.66 inches more than the previous state record, which was set after Hurricane/Tropical Storm Irene made landfall and dumped precipitation across the Northeast in 2011.

In general, rainfall amounts in the worst-hit areas ranged from 5 to 13 inches, with the most extreme amounts hitting highly localized areas, as is typical of such storms.

Such extreme rainfall events are expected to happen more in a warming world, and outside of the usual tropical storms that dump tremendous amounts of water. The reason is that as the Earth’s atmosphere warms, it can hold more water vapor, which means that storms have more available water to wring out of the air as rain in any particular storm. Of all the regions in the U.S., the Northeast has seen the most dramatic increase in heavy downpours with a 71 percent increase since 1958.