An intensifying low pressure system that helped generate its own cold air produced heavy snow across most of Eastern Pennsylvania. While the air was cold enough for precipitation to fall as snow across the Poconos and Lehigh Valley, the precipitation intensity was so heavy farther southeast, that the rain changed to snow faster and lasted longer than anticipated.  Unfortunately this occurred during midday on a Monday. While schools were closed from Upper Bucks and Montgomery Counties northward, schools were open farther south. As schools, businesses and malls closed early in Philadelphia and the nearby suburbs, an early rush hour produced dire and nightmarish consequences. Numerous accidents congested nearly every major roadway to the point that emergency personnel and snow plows could not get through. Many tractor trailers jackknifed and many vehicles including school buses skidded into ditches and could not negotiate hills. Thousands of motorists were stranded on roadways, many abandoned their vehicles adding to the traffic congestion. There were thousands of accidents. Most of them only caused minor injuries.  Stories of 30 minute commutes turning into 6 hour nightmares were common. Many communities declared snow emergencies. In addition, the heavy wet snow downed numerous trees, tree limbs and power lines, particularly in the Philadelphia northwest suburbs. PECO Energy reported 180,000 customers lost power. Farther north, the snow was more powdery and only about 9,000 outages were reported. Repair efforts were hampered by the traffic congestion. Many slip and fall and snowthrower accidents occurred. Several pedestrians were injured when struck by either snow plows or vehicles. There was one reported heart attack death caused by shoveling snow (in Chester County). Cell phone use overwhelmed the capacity of their systems. Accumulations were generally between 6 and 18 inches. Some lesser accumulations occurred within parts of Philadelphia and lower parts of the nearby suburbs. The widespread highest amounts occurred across the southern Poconos and  the Lehigh Valley. Many schools were closed the following day (the 6th). Most power was restored by the 6th.In the Poconos, the snow began falling shortly after midnight on the 5th and fell the heaviest between 8 a.m. and 4 p.m. EST. The worst accident occurred on the Northeast Extension of the Pennsylvania Turnpike near Lehighton when a tractor trailer traveling northbound struck the concrete median. Pieces of the median fell into the southbound lanes and the hood of the tractor trailer flew off and struck another vehicle. The road was closed for over an hour. In Mahoning Township, an oil delivery truck slid on ice and flipped on its side. This was the highest accumulation in the Stroudsburg area since the blizzard of 1996.    In the Lehigh Valley and Berks County, snow began falling around 1 a.m. EST, fell the heaviest between 9 a.m. and 3 p.m. EST and ended around 7 p.m. EST. In the Lehigh Valley, a tractor trailer accident backed up Interstate 78 for 6 miles during the afternoon. Trucks could not negotiate the hill. In Easton, a tractor trailer jackknifed on U.S. Route 22 near Cemetery Curve and backed up the roadway throughout the afternoon. Even a fire truck stalled in the snow. Half of the flights at the Lehigh Valley International Airport were cancelled. In Berks County, both directions of the Pennsylvania Turnpike were closed around Reading because of three jackknifed tractor trailers. A pedestrian was struck by a plow in Morgantown. Boyertown, Hamburg and Sinking Spring had the most power outages. Philadelphia and the surrounding suburbs bore the brunt of the damage from this winter storm. Precipitation started as a mixture of snow, sleet and rain just after midnight in the far northern suburbs and as plain rain elsewhere. As precipitation intensity increased, and the low began to pull offshore, precipitation changed to all snow in the far north and the transition started farther south. The rain changed to all snow around Doylestown (Bucks County) at 9 a.m. EST and in Philadelphia around noon EST. The heaviest snow fell between 11 a.m. and 5 p.m. EST. Ironically, when the precipitation intensity decreased, rain began mixing with the snow again at the Philadelphia International Airport. The snow ended by 8 p.m. EST. Accidents caused cars, trucks and buses to be at a standstill from 1 p.m. EST into the early evening on the Schuylkill Expressway (Interstate 76) , the Blue Route (Interstate 476), the Northeast Extension of the Pennsylvania Turnpike, U.S. Route 30, U.S. Route 202, U.S. Route 422, Pennsylvania State Route 309,  Pennsylvania State Route 611, Ridge Pike and Germantown Pike.  A drive from Center City Philadelphia to King of Prussia in Montgomery County took one motorist 5 hours. Many vehicles ran out of fuel and were abandoned on these roadways slowing or preventing snow removal. There were 500 reports of stranded motorists in Delaware County alone.  Plow trains had better luck clearing access roads first than main roadways because of the congestion. In Bucks County, a jackknifed tractor trailer near Quakertown crippled the Northeast Extension of the Pennsylvania Turnpike for most of the day.  In Montgomery and Bucks Counties, school buses became stuck climbing hills and/or slid into ditches. This occurred to three buses in Lower Moreland Township (Montgomery County) alone. In Abington Township, a six foot wide tree crashed onto four vehicles, two were occupied, but no serious injuries occurred. A tree fell on a vehicle in Horsham Borough also. Every major roadway in Whitpain Township (Montgomery County) was gridlocked. Emergency officials were overwhelmed. In Lower Merion Township, for example, there were 300 responses from emergency personnel. In Chester County, about a half dozen school buses were stuck on Charlestown Township roads. In Paoli, students were stuck at the school overnight. Buses could not reach them. In Delaware County, in Marple Township, a pedestrian was struck during a two vehicle accident. In Radnor Township, 1,200 students were stranded because bus drivers could not make it back to work. The last bus left the school at 745 p.m. EST.    Specific accumulations included in Berks County: Mohnton 14.5 inches, Bechtelsville 13 inches, Reading 10 inches and Lincoln Park 9.5 inches, in Bucks County: 18 inches in Springtown, 14.7 inches in Chalfont, 13.5 inches in Sellersville, 8 inches in Doylestown and 4 inches in Levittown, in Carbon County: 11 inches in Albrightsville, 10 inches in Meckesville and 9 inches in Jim Thorpe and Lehighton, in Chester County: 11 inches in Kimberton, 10 inches in Exton, 7.4 inches in Glenmoore, 6 inches in Valley Forge and 4 inches in Oxford. In Delaware County: 12.4 inches in Radnor, 7.5 inches in Newtown and 4 inches in Crum Creek, In Lehigh County: 17.5 inches in Coopersburg, 17 inches in Salisbury Township, 16 inches in Alburtis and 13 inches at the Lehigh Valley International Airport, in Monroe County: 16 inches in Saylorsburg, 13.5 inches in East Stroudsburg, 12 inches in Scotia and 10 inches in Pocono Summit, In Montgomery County: 14 inches in Palm, 13 inches in King of Prussia, 12 inches in Pottstown, 11 inches in Hatfield and 9 inches in Whitemarsh, in Northampton County: 18 inches in Williams Township, 17 inches in Palmer Township, 13 inches in Easton and 12 inches in Bethlehem and in Philadelphia County: 8 inches in Manayunk, 5.5 inches in Somerton, 4 inches at the Franklin Institute and 3 inches at the Philadelphia International Airport. The low pressure system responsible for the heavy snow developed along a stationary front just east of Florida on the 4th. By the morning of the 5th, it moved north to near Elizabeth City, North Carolina. It then intensified rapidly (a drop of about 25 millibars during the next 24 hours) as it moved northeast  and reached Nova Scotia during the morning of the 6th. The air mass over the region was marginally cold for snow, especially around Philadelphia. But, the precipitation intensity was so great (storm total water equivalents were around 1.5 inches), that the heat required to melt the snow aloft (called the latent heat of fusion) chilled the air mass and made the snow capable of reaching the ground. This type of snowstorm is typically called a "warm snowstorm" because the low pressure system itself manufactures the cold air needed to make the snow reach the ground. In a so-called standard snowstorm the air mass is cold enough at the start to support snow. Warm snowstorms are not only difficult to predict, but also because of the lack of cold air, usually produce heavy wet snow that easily can take down trees, tree limbs and power lines.

Heavy Snow in NORTHAMPTON, PENNSYLVANIA
From 05-FEB-01 01:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Winter Storm in PHILADELPHIA, PENNSYLVANIA
From 05-FEB-01 12:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Heavy Snow in BERKS, PENNSYLVANIA
From 05-FEB-01 01:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Winter Storm in BUCKS, PENNSYLVANIA
From 05-FEB-01 06:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Heavy Snow in CARBON, PENNSYLVANIA
From 05-FEB-01 01:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Winter Storm in CHESTER, PENNSYLVANIA
From 05-FEB-01 06:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Winter Storm in DELAWARE, PENNSYLVANIA
From 05-FEB-01 12:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Heavy Snow in LEHIGH, PENNSYLVANIA
From 05-FEB-01 01:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER

Heavy Snow in MONROE, PENNSYLVANIA
From 05-FEB-01 01:00:00 to 05-FEB-01 20:00:00 (EST)
Reported by: TRAINED SPOTTER

Winter Storm in MONTGOMERY, PENNSYLVANIA
From 05-FEB-01 05:00:00 to 05-FEB-01 19:00:00 (EST)
Reported by: TRAINED SPOTTER