Winter Storm and Sleet in Pennsylvania, February 18 to 19, 2000

Snow spread Eastern Pennsylvania between 4 a.m. and 7 a.m. EST on Friday, February 18th. As warmer air moved in aloft as the day progressed, the snow changed to sleet and then to rain. Unfortunately the change to rain occurred across most of Berks County, the Lehigh Valley and the Poconos when surface temperatures were well below freezing and never reached it throughout this event. Farther southeast, the change to plain rain occurred around noon in the local Philadelphia area, but a period of freezing rain occurred into the afternoon in upper sections of Bucks, Montgomery and Chester Counties. Farther to the north in Berks County and the Lehigh Valley, the change to sleet and freezing rain occurred around 3 p.m. EST. In the Poconos it occurred around 6 p.m. EST. Periods of light rain persisted into the morning of the 19th across the greater Philadelphia Metropolitan area and parts of Berks County, but light freezing rain continued to occur elsewhere across Eastern Pennsylvania. Snowfall accumulations prior to the changeover averaged between 2 and 7 inches, with the highest accumulations in the Poconos. Across Berks County, the Lehigh Valley and the Poconos between two-tenths and half an inch of ice (freezing rain) accrued on exposed surfaces, the greatest accretions occurred in the Poconos. The snow and ice led to numerous accidents. The snow and ice also caused dozens of flights to be canceled from the Lehigh Valley International Airport. In Chester County, the emergency center responded to 770 calls, about double the normal number of accidents. The worst accident was a four car collision with injuries at the intersection of Pennsylvania State Route 100 and Fellowship Road in Upper Uwchlan Township. Cars became stuck on hills, in ditches and slid off roads. In Berks County, the westbound lanes of the West Shore Bypass were closed about 11 a.m. EST after three accidents. In Northampton County, one person was injured when a tractor trailer collided with a vehicle in the westbound lanes of Interstate 78 at 830 p.m. EST and was dangling from a bridge just west of Pennsylvania State Route 412 in Hellertown. In the Poconos, tractor trailers were jackknifing on Interstate 80. Accumulations included 7 inches in Saylorsburg (Monroe County), 6 inches in Long Pond (Monroe County) and Schubert (Berks County), 5.5 inches in East Stroudsburg (Monroe County), 5.1 inches in Williams Township (Northampton County), 5 inches in Mertztown (Berks County), 4 inches in Lehighton (Carbon County), Perkasie (Bucks County) and Vinemont (Berks County), 3.9 inches at the Lehigh Valley International Airport, 3.8 inches in Pottstown (Montgomery County), 3.6 inches at the Philadelphia International Airport and 3 inches in Chadds Ford (Delaware County), Exton (Chester County) and Reading (Berks County). The highest accretion of ice reported was half an inch in Tobyhanna (Monroe County). The cause of the wintry weather were a pair of low pressure systems that developed in the Southern Plains during the day on the 17th. By Friday morning the 18th, one low was in the central Ohio Valley, the other near Springfield, Missouri. A large high pressure system moved across the northern Middle Atlantic States and New England on the 17th and 18th and supplied a fresh supply of cold air. The lows' storm track passed them south of the state during the night of the 18th and the morning of the 19th. The proximity of these lows and the counterclockwise circulations around them from the nearby Atlantic Ocean were enough to raise temperatures above the freezing mark in and around Philadelphia. But on a relative basis, these low pressure systems were weak. While warmer air was able to move in aloft; the surface winds were not strong enough to either mix the warm air down or bring it farther inland from the Atlantic Ocean. The two low pressure systems prolonged the precipitation and this event lasted around 24 hours.