A large high pressure system over nearby Canada and a low pressure that passed south of the region set the stage for a protracted winter storm from Berks County and the Lehigh Valley northward and a winter weather event elsewhere across Eastern Pennsylvania.  Precipitation began as light freezing rain during the late afternoon and evening of the 2nd. Precipitation changed to light snow in the Poconos, Berks County and the Lehigh Valley overnight. Some sleet also fell. In the Philadelphia northwest suburbs, precipitation fell as a mixture of light freezing rain, sleet and snow. Throughout the area, precipitation amounts overnight were light, generally just a couple of hundredths of an inch. Steadier precipitation moved into the region toward daybreak on the 3rd. By then warmer air aloft caused precipitation to fall as mainly freezing rain. Only in the Poconos did precipitation change back and forth between snow and freezing rain. Eventually enough warm air moved in near the surface for precipitation to change to plain rain in the Philadelphia northwest suburbs during the morning (before Noon EST). Ice accretions were generally one tenth of an inch or less. Farther north, temperatures struggled to reach near freezing during the daylight hours. As a result a mixed bag of wintry precipitation occurred in Berks County, the Lehigh Valley and the Poconos. Some valley locations changed to rain, while higher terrain locations in Berks County and the Lehigh Valley continued to have freezing rain. In the Poconos precipitation continued to fall as snow during heavier precipitation bursts and freezing rain at other times. As the low pressure system moved farther offshore and the winds shifted to the north, precipitation changed to all snow in the Poconos during the late afternoon of the 3rd and in Berks County and the Lehigh Valley during the evening of the 3rd. In far northern sections of Philadelphia's northern suburbs precipitation changed to freezing rain during the evening of the 3rd and then over to snow toward midnight. The snow ended before daybreak on the 4th. Across the far northern Philadelphia suburbs, an additional one tenth of an inch accrued on most exposed surfaces with little if any snow accumulation except for higher terrain toward Allentown. In Berks County and the Lehigh Valley, around one-quarter of an inch of ice accrued on exposed surfaces and then between 1 to 3 inches of snow accumulated on top of the ice. In the Poconos, around one quarter of an inch of ice accrued on exposed surfaces and then between 3 and 8 inches of snow accumulated on top of the ice. Commuting on untreated surfaces was treacherous throughout this event. Specific accumulations included 8 inches in Mount Pocono (Monroe County), 5.8 inches in East Stroudsburg (Monroe County), 5.5 inches in Bossardsville (Monroe County), 4.3 inches in Lehighton (Carbon County), 3 inches in Jim Thorpe (Carbon County), 2.5 inches in Reading (Berks County), 2.2 inches in Hamburg (Berks County) and Springtown (Bucks County) and 0.5 inches at the Lehigh Valley International Airport.  The low pressure system responsible for the wintry weather developed in the Southern Plains on January 1st and moved into the Tennessee Valley during the morning of the 2nd. By the morning of the 3rd, it moved into North Carolina where a secondary formed near Norfolk, Virginia. The low then moved northeast and passed just to the south of Cape Cod during the morning of the 4th. While this low passed south of the area, a high pressure system remained nearly stationary over nearby Canada and provided and helped entrench cold air near the surface. This causes precipitation to fall as freezing rain even though it was warm enough aloft for the falling snow to change to plain rain.

Winter Weather in BUCKS, PENNSYLVANIA
From 02-JAN-03 22:00:00 to 03-JAN-03 09:00:00 (EST)
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Winter Weather in CHESTER, PENNSYLVANIA
From 02-JAN-03 22:00:00 to 03-JAN-03 09:00:00 (EST)
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Winter Weather in MONTGOMERY, PENNSYLVANIA
From 02-JAN-03 22:00:00 to 03-JAN-03 09:00:00 (EST)
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Winter Weather in BUCKS, PENNSYLVANIA
From 03-JAN-03 21:00:00 to 04-JAN-03 04:00:00 (EST)
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Winter Weather in CHESTER, PENNSYLVANIA
From 03-JAN-03 21:00:00 to 04-JAN-03 04:00:00 (EST)
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Winter Weather in MONTGOMERY, PENNSYLVANIA
From 03-JAN-03 21:00:00 to 04-JAN-03 04:00:00 (EST)
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Winter Storm in BERKS, PENNSYLVANIA
From 02-JAN-03 21:00:00 to 04-JAN-03 01:00:00 (EST)
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Winter Storm in CARBON, PENNSYLVANIA
From 02-JAN-03 17:30:00 to 04-JAN-03 04:00:00 (EST)
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Winter Storm in LEHIGH, PENNSYLVANIA
From 02-JAN-03 20:30:00 to 04-JAN-03 03:00:00 (EST)
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Winter Storm in MONROE, PENNSYLVANIA
From 02-JAN-03 17:30:00 to 04-JAN-03 04:00:00 (EST)
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Winter Storm in NORTHAMPTON, PENNSYLVANIA
From 02-JAN-03 20:30:00 to 04-JAN-03 04:00:00 (EST)
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