Winter Storm and Winter Weather in Pennsylvania, December 13 to 14, 2000

A winter storm of sleet and freezing rain encrusted much of Eastern Pennsylvania with a combination of about three-quarters of an inch of sleet and ice. Precipitation began during the late evening of the 13th as a mixture of sleet and snow in the Poconos, a mixture of sleet and freezing rain in Berks and Bucks Counties and the Lehigh Valley and as mainly freezing rain across the rest of southeast Pennsylvania. Precipitation changed to plain rain in Philadelphia and Delaware Counties by around 3 a.m. EST on the 14th with ice accretions generally less than one-tenth of an inch. But by that time across the rest of Eastern Pennsylvania precipitation was falling as mainly freezing rain. Temperatures slowly rose above freezing from southwest to northeast that morning, but took until around 830 a.m. EST for the last of the sub-freezing air to be scoured from the Poconos. The hardest hit locations were in a strip across Berks east into Upper Chester, Montgomery and Bucks Counties where freezing rain was the predominate precipitation type. Ice accretions in these areas averaged around half an inch. Elsewhere they were around one-quarter of an inch as either more sleet fell (farther to the north) or the precipitation changed to plain rain (closer to Philadelphia) faster. The ice knocked down tree limbs and power lines. In Berks County, about 16,000 customers lost power. Hardest hit were the rural locations in the seven westernmost townships in the county. PECO Energy reported about 16,500 customers lost power in Chester, Montgomery and Bucks Counties. There were several accidents because of the slippery roads, but the number was relatively low due to the time the most hazardous precipitation was falling. Schools were closed in the Poconos. Two hour opening delays were common elsewhere. A few other schools were closed because of the lack of power. Since most of the sleet and ice fell overnight, the number of traffic accidents were relatively low. A strong high pressure system nestled itself across the northeastern United States on the 13th. It brought some very cold and dry air into the region. As the high moved offshore the evening of the 13th, temperatures did not have enough time to recover to the freezing mark. During the evening of the 13th, the low pressure system moved from the lower Tennessee Valley northeast into the upper Ohio Valley during the early morning of the 14th. A secondary low pressure system did form in Chesapeake Bay toward dawn on the 14th and moved northeast through New Jersey during the morning. It eventually became the primary low pressure system on that afternoon as it headed toward Cape Cod. These lows were relatively weak (their central pressures as of 1 p.m. EST on the 14th were only around normal sea level pressure). Thus as warmer air was streaming in aloft, the weak southeast flow from the relatively warm Atlantic Ocean took a while to move inland and change the freezing rain to plain rain.