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Northeast Regional Climate Center |
After a cool August, temperatures rebounded in September. The Northeast's monthly average of 62.3 degrees was 2.1 degrees above normal. This was 0.8 degrees warmer than September 2005 and the warmest September since 1999. State departures ranged from 0.9 degrees above normal in Maine to 3.2 degrees above normal in New York.
September was the third month in a row that the Northeast was wetter than normal. The region received an average of 6.02 inches of rain, which was 152% of the September normal. This was the wettest September since 1999 and the 5th wettest since records began in 1895. Both Pennsylvania and West Virginia had their wettest September since 1895. West Virginia's previous rainfall record for September was set in 2003 and Pennsylvania's was set in 1975.
The remnants of three tropical systems accounted for the excessive rainfall this month. The focus of these systems was the southern two thirds of the region, with the greatest rainfall amounts shifting from west to east with each storm.
The first system, Frances, brought wet and stormy conditions to the region on the 8th and 9th. As it traveled from the Gulf of Mexico into the continental US, the tropical depression merged with a stationary front, setting up a conveyer belt of tropical moisture over the region. While most affected areas received from 3 to 5 inches, a few locations in western Pennsylvania saw up to 9 inches of rain. Flash flood reports came in from West Virginia to southwestern New Hampshire, with the heaviest rain and greatest impacts in western and central Pennsylvania, western and eastern West Virginia, the panhandle of Maryland and western New York. There were reports of evacuations, road washouts, and significant property damage totaling $15-20 million.
On September 17th, the remnants of Hurricane Ivan moved north along the Appalachians and interacted with an approaching cold front. This collaboration of weather systems lead to rainfall totals of 3-5 inches over the central portion of the region, with localized totals exceeding 8 inches. The resultant flooding was exacerbated by antecedent conditions from the heavy rainfall the previous week, especially in western and central Pennsylvania. Severe storms also produced strong winds and tornados in Pennsylvania and West Virginia, where over 70 homes and 30 businesses were destroyed with many more damaged. Pennsylvania bore the brunt of this event. Throughout the state, well over 10,000 structures were damaged or destroyed, hundreds of roads and bridges were closed, flood control structures were weakened, and flood levels at a few locations exceeded their all-time highs. In eastern Pennsylvania, flooding occurred along the entire length of the Susquehanna River, and the Delaware River saw its worst flooding since 1955. Other areas reporting serious storm damage were central Maryland, northern Delaware, western New Jersey, southeastern New York, southern and western Connecticut and central Massachusetts. Damage estimates for the region exceeded 300 million dollars, with many areas declared federal disaster areas.
The remnants of Hurricane Jeanne tracked along a stalled front near the Interstate 95 corridor on the 28th, causing torrential downpours over the southeast portion of the region. With rainfall totals averaging 3 to 6 inches, Northern Delaware, central and northeast Maryland, south central and southeastern Pennsylvania, most of New Jersey and coastal New York saw the worst from this weather system. For the third time this month, water rescues, road closures, flooded basements and evacuations disrupted the normal routine and caused millions of dollars in damages.
Monthly Summary of State Temperature and Precipitation Averages.
