July 9, 2014 —
SULLIVAN COUNTY, NY — The torrential rains came again to the Upper Delaware Valley, resulting in flooding, closed roads, evacuations and thousands of residents without power. But this time, there were no serious injuries.
The storms hit Youngsville, Callicoon Center and Jeffersonville hardest, marking about the fifth time flooding has come to this small area since 2004. Six to eight inches of rain fell in the area over two days, causing $1.5 million or more in damages by some estimates.
So what has caused these storms that have resulted in so much damage over the past decade or more? The answer is a complicated mix of factors, as Kat Hawley, a meteorologist with the National Weather Service in Binghamton explained.
She said in order to get these storms that produce very heavy rain, the environmental conditions have to be just right, with lots of energy ready to feed the storm. She said the flash flooding depends in part on how much rain the area has had in previous days, and “Sullivan County has been hit quite a bit with showers continuously.”
She said, “We’re in a very active pattern and we get into these active patterns once or twice a summer, we have extremely moist air. We have been well above normal for quite some time in what we call PWAT values,” which indicates the amount of moisture that may be available as precipitation, and the area has had systems with an abnormally high amount of moisture available from the Atlantic Ocean.
As for the fact that the Jeffersonville/Youngsville area received more rain than surrounding communities, Hawley said there is a phenomenon known as training in which multiple thunderstorms are spawned and move over the same area in a relatively short period of time because there is nothing in the atmosphere to move everything along.
What about the short-term outlook for more storms?
Speaking on July 7, she said “The six- to 10-day and right to 14-day outlook for precipitation for our area is above average, but that doesn’t guarantee that we’re going to have heavy precipitation. It means that we get into these systems once or twice a year and we’re currently in one. So we get multiple little storm systems, multiple fronts moving through in a way that they can tap into Atlantic moisture, and it comes up from the Gulf of Mexico as well.”
So it’s the same kind of system that produced the storms on July 2 and 3.