WINTER STORM SUMMARY FOR
DECEMBER 19, 2009 TO DECEMBER 20, 2009 EVENT

Synopsis

A significant Nor'easter impacted the Mid Atlantic region from Saturday December 19th through the morning of Sunday December 20th. An area of low pressure developed in the Gulf of Mexico on Friday December 18th, and this low then tracked to just east of the Carolina coast by Saturday morning December 19th. This low pressure system intensified Saturday as it continued to track northeastward along the East Coast. With ample cold air in place, snow began falling across much of the area during the pre-dawn hours of Saturday. As the low strengthened, heavier bands of snow developed and tracked through the Delmarva Peninsula and southern New Jersey. By late afternoon and evening, significant snow accumulations were occurring in these areas. Some mixing with rain occurred along the southern New Jersey coast during the afternoon, and sleet was also reported during the afternoon along the eastern shore of Maryland. Farther north, snow began during the late afternoon and persisted into the night across northern New Jersey and the Lehigh Valley in northeast Pennsylvania. Accumulating snow continued across much of the Mid Atlantic region through midnight, and light snow showers lasted across portions of central to northern New Jersey through mid-morning on Sunday December 20th. The low pressure system tracked northeast and away from the region through the remainder of Sunday.

Watches/Warnings/Advisories

A Winter Storm Watch was issued at 330 pm on Thursday December 17th for the following areas: New Castle, Kent, and Sussex in Delaware; Cecil, Kent, Queen Annes, Talbot, and Caroline in Maryland; Salem, Gloucester, Camden, Northwestern Burlington, Ocean, Cumberland, Atlantic, Cape May, and Southeastern Burlington in New Jersey; Delaware and Philadelphia in Pennsylvania. At 1012 pm on Thursday December 17th, a Winter Storm Watch was issued for the following areas: Hunterdon, Somerset, Middlesex, Western Monmouth, Eastern Monmouth, and Mercer in New Jersey; Berks, Chester, Montgomery, and Bucks in Pennsylvania. A Winter Storm Warning was issued at 440 am on Friday December 18th for the following areas: New Castle, Kent, and Sussex in Delaware; Cecil, Kent, Queen Annes, Talbot, and Caroline in Maryland; Salem, Gloucester, Camden, Northwestern Burlington, Ocean, Cumberland, Atlantic, Cape May, and Southeastern Burlington in New Jersey; Delaware and Philadelphia in Pennsylvania. Also on Friday December 18th at 440 am, a Winter Storm Watch was issued for the following areas: Sussex, Warren, and Morris in New Jersey; Carbon, Monroe, Lehigh, and Northampton in Pennsylvania. At 114 pm on Friday December 18th, a Winter Storm Warning was issued for the following areas: Hunterdon, Somerset, Middlesex, Western Monmouth, Eastern Monmouth, Mercer, Sussex, Warren, and Morris in New Jersey; Carbon, Monroe, Lehigh, Northampton, Berks, Chester, Montgomery, and Bucks in Pennsylvania.

Precipitation/Temperatures/Winds

Significant snow accumulations were recorded from this event. In fact, Philadelphia recorded its third highest snowfall ever for any single event, with 23.2 inches at the Philadelphia International Airport. Snowfall totals ranging from 20 to 25 inches extended from central Ocean and Burlington counties in New Jersey southwestward to Kent county in Maryland. Farther south, snowfall amounts of 10 to 20 inches occurred from Atlantic county New Jersey southwestward to Caroline and Talbot counties in Maryland. A band of 5 to 10 inch snowfall accumulations occurred from central Cape May county in New Jersey southward into Sussex county Delaware. North of the Philadelphia area, 10 to 15 inch accumulations were tallied from Monmouth county in New Jersey westward into northern Chester county in Pennsylvania. Meanwhile, 5 to 10 inch accumulations occurred across much of northern New Jersey and westward into Berks and Lehigh counties in Pennsylvania. Temperatures remained in the 20s for most areas throughout the event, yielding a light, fluffy snow. Winds averaging 15 to 25 mph for most areas resulted in blowing and drifting snow with reduced visibilities.

Significant Impacts/Aspects

This was the first heavy snowfall of the winter season, and as the fluffy snow fell, it quickly accumulated on roadways. Blowing and drifting snow also proved to be a challenge as road crews across the region tried to keep up with the accumulating snow. Snowfall rates of 1 to 2 inches per hour along with thunder and a few lightning strikes were reported across portions of Gloucester and western Atlantic counties. Even though the storm exited the region by Sunday morning, schools across central to southern New Jersey, as well as schools in Philadelphia, were closed on Monday because additional time was needed to clear roads and sidewalks across the area.

Notes

Information contained in this summary is preliminary. More complete and/or detailed information may be contained in subsequent monthly NOAA storm data publications.