In addition to socking the Washington metro area with historic rainfall amounts and severe flooding, the remnants of Tropical Storm Lee brought devastating flooding to northeastern Pennsylvania and parts of New York State. Rainfall totaling one foot or more caused the Susquehanna River to surge to unprecedented levels - besting the benchmark flood for the region, which occurred as a result of Hurricane Agnes in 1972. According to the Associated Press, at least 15 deaths have been blamed on Lee and its remnants, including seven deaths in Pennsylvania.
Authorities had to evacuate most of Wilkes-Barre, Penn., due to concerns that the levees that were built to withstand another Agnes-level flood might not hold. In the end, the levees did their job - but they may have contributed to more severe flooding in surrounding areas, as detailed in an article in the Philadelphia Inquirer, which states:
When the U.S. Army Corps of Engineers called in 1979 for raising levees in Wilkes-Barre by three to five feet after Tropical Storm Agnes, it cited the nearly $3 billion in damage that storm had caused to justify the expense. In essence, shoring up the flood-control system in the city of 42,000 in the heart of Pennsylvania coal country would cost less than would repairing houses and businesses after another catastrophic flood, engineers said.
But in a handful of smaller neighboring communities on the river’s west bank - West Pittston, Plains, and low-lying Jenkins Township - the figures didn’t add up.
It was there Friday that agitated murky water crept to the rooftops, National Guardsmen launched rescue efforts from second-story windows, and the torrent rose much higher than anyone predicted as the remnants of another tropical storm - Lee - pummeled one of the most flood-prone regions in the United States.
In Wilkes-Barre itself, the Susquehanna River crested at 42.66 feet, breaking the previous record of 40.91 feet. (See this National Weather Service site for more information on Pennsylvania river crests). Harrisburg received 13.30 inches of rain, and a whopping 15.20 inches fell in Lancaster County during Sept. 5-8.
In Binghamton, N.Y., where about 20,000 residents were evacuated, the Susquehanna crested at 25.7 feet, the highest on record. Binghamton received 7.49 inches of rain on Sept. 7, the most rainfall recorded on a single day in that station’s history. Following the rains from Lee, 2011 is now Binghamton’s wettest year on record - and it’s only September.
As was the case in the D.C. area, the heavy rains in Pennsylvania and New York were the result of a combination of moisture from the remnants of Lee that crept along a slow-moving frontal boundary that had draped itself across the region, acting as a triggering and focusing mechanism for heavy showers and thunderstorms.
Although the proximate weather-related causes of this situation are quite clear, as FEMA spokesman Dave Bollinger told a reporter for the Citizens Voice newspaper in Wilkes-Barre, climate change is already helping to raise the odds that extreme rainfall events will occur.
“What’s happening is a 345-year flood you aren’t supposed to have is happening every 50 years,” Bollinger said. “We are seeing the effects of changing weather patterns.”
Two studies published in the journal Nature earlier this year shed new light on how manmade climate change may be influencing precipitation extremes, in part by increasing the amount of water vapor in the air.