A wintry mix of mainly sleet and freezing rain affected Pennsylvania on the 5th. Ice accretions averaged one twentieth to one quarter of an inch and any snow and sleet accumulations averaged less than one inch. Numerous accidents were reported, especially during the morning in the Lehigh Valley.
In Philadelphia and the northwest suburbs, precipitation started as sleet between 3 a.m. EST and 6 a.m. EST on the 5th, changed to freezing rain between 6 a.m. and 8 a.m. EST and plain rain by Noon EST, except in Bucks County where freezing rain persisted through the middle of the afternoon. Ice accretions rainged from less than one twentieth of an inch in Philadelphia to around one tenth of an inch in Bucks County. Across Berks County and the Lehigh Valley, precipitation started as sleet around 5 a.m. EST on the 5th, changed to freezing rain between 6 a.m. EST and 8 a.m. EST and then to plain rain between 1 p.m. and 3 p.m. EST that afternoon. Ice accretions averaged around one tenth of an inch. In the Poconos, precipitation started as snow and sleet around 5 a.m. EST on the 5th and changed to freezing rain and sleet between 7 a.m. and 9 a.m. EST and changed to plain rain during the late afternoon. Ice accretions averaged one quarter of an inch and snow and sleet accumulations were less than half an inch.
Across Eastern Pennsylvania numerous interstates and major roadways were affected by vehicle accidents and included Intestates 78, 76, 476, 80, and 380, as well as State Routes 309 and United States Route 1. Major road closures were reported in Berks, Lehigh, and Northampton Counties. In Berks County, Interstate 78 westbound was closed for five miles between the Lenhartsville and Hamburg exits due to an accident. A section of westbound Interstate 78 was also closed in Lehigh County because of another accident. In Northampton County, the eastbound Interstate 78 bridge into New Jersey was closed for salting.  Northampton County overall was hit the hardest with road closures and accidents. In Bethlehem, Pennsylvania State Route 378 was closed after several vehicles including an Easton Coach Tour Bus and a tractor-trailer skidded off of it. U.S. Route 22 in Wilson was closed after a van flipped over. Pennsylvania State Route 33 was very icy and a vehicle rolled over in Bushkill Township. Two vehicles flipped over in Upper Mount Bethel Township. Both Pennsylvania State Routes 248 and 512 were closed in Bath. The continuing wintry weather created shortages of salt supplies as well as exceeding snow removal budgets for many municipalities.
The wintry mix was caused by a low pressure system that moved northeast along the eastern seaboard on the 5th. The low moved from coastal North Carolina at the onset of precipitation on the early morning of the 5th, reached the Delmarva Peninsula at 1 p.m. EST on the 5th and moved through New Jersey during the late afternoon and early evening on the 5th. There was no typical high pressure system to lock the cold air in place, but a large snow pack across the region was the de facto cold air source near the surface and prolonged the period of freezing rain than would typically be the case given the synoptic regime.

Winter Weather in MONROE, PENNSYLVANIA
From 05-FEB-11 05:00:00 to 05-FEB-11 17:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in CARBON, PENNSYLVANIA
From 05-FEB-11 05:00:00 to 05-FEB-11 17:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in LEHIGH, PENNSYLVANIA
From 05-FEB-11 05:00:00 to 05-FEB-11 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in NORTHAMPTON, PENNSYLVANIA
From 05-FEB-11 05:00:00 to 05-FEB-11 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in BERKS, PENNSYLVANIA
From 05-FEB-11 04:00:00 to 05-FEB-11 13:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in MONTGOMERY, PENNSYLVANIA
From 05-FEB-11 03:00:00 to 05-FEB-11 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in CHESTER, PENNSYLVANIA
From 05-FEB-11 05:00:00 to 05-FEB-11 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in BUCKS, PENNSYLVANIA
From 05-FEB-11 05:00:00 to 05-FEB-11 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in PHILADELPHIA, PENNSYLVANIA
From 05-FEB-11 06:00:00 to 05-FEB-11 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in DELAWARE, PENNSYLVANIA
From 05-FEB-11 06:00:00 to 05-FEB-11 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet