A low pressure system brought mainly snow to the Poconos, a wintry mix of snow, sleet, freezing rain and rain to the Lehigh Valley and some freezing rain and sleet to Berks County and the Philadelphia northwest suburbs overnight on the 15th. Snowfall in the Poconos averaged 3 to 6 inches and in the Lehigh Valley around one inch. Ice accumulations in Berks County, the Lehigh Valley and the northern and far western Philadelphia suburbs averaged one to two tenths of an inch. The wintry weather made the morning commute on the 16th hazardous and longer than average, especially if traveling on untreated roadways.
In the Poconos, snow began during the late evening of the 15th and ended around 7 a.m. EST on the 16th. In the Lehigh Valley, precipitation started as sleet and rain. As temperatures dropped overnight and precipitation intensity increased, precipitation fell as either snow or freezing rain. Toward morning on the 16th, precipitation fell as freezing rain and the steady precipitation ended in the middle of the morning. In the Philadelphia northwest suburbs, precipitation started as rain. As temperatures dropped overnight and precipitation intensity increased, precipitation fell as either sleet or freezing rain. Toward morning on the 16th, precipitation changed back to plain rain or plain rain mixed with sleet at times. The steady precipitation ended in the middle of the morning.
Representative snowfall included 5.3 inches in Tobyhanna (Monroe County), 5.0 inches in Albrightsville (Carbon County), 4.6 inches in East Stroudsburg, 4.5 inches in Summit Hill (Carbon County) and Pocono Summit (Monroe County), 4.0 inches in Saylorsburg (Monore County), 3.9 inches in Lehighton (Carbon County), 3.0 inches in Palmerton (Carbon County), 1.8 inches in Moorestown (Northampton County), 1.0 inch in Martins Creek (Northampton County), 0.8 inches in Schnecksville (Lehigh County) and 0.5 inches at the Lehigh Valley International Airport. Ice accumulations included 0.20 inches in Forks Township (Northampton County).
The wintry weather was caused by a series of low pressure systems that developed along a frontal boundary in the southeastern United States on the morning of the 15th. The lows consolidated into one just east of Wilmington, North Carolina overnight on the 15th and then moved northeast. By 7 a.m. EST on the 18th, the low was located around one hundred miles east of the New Jersey coast. The northeasterly flow around that storm track prevented warmer air at the surface (and in the Poconos aloft also) from ever moving farther north than Philadelphia and its immediate suburbs.

Winter Weather in MONROE, PENNSYLVANIA
From 15-JAN-13 23:00:00 to 16-JAN-13 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in CARBON, PENNSYLVANIA
From 15-JAN-13 23:00:00 to 16-JAN-13 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in UPPER BUCKS, PENNSYLVANIA
From 16-JAN-13 00:00:00 to 16-JAN-13 18:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Winter Weather in LOWER BUCKS, PENNSYLVANIA
From 16-JAN-13 00:00:00 to 16-JAN-13 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Winter Weather in WESTERN CHESTER, PENNSYLVANIA
From 16-JAN-13 01:00:00 to 16-JAN-13 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Winter Weather in WESTERN MONTGOMERY, PENNSYLVANIA
From 16-JAN-13 00:00:00 to 16-JAN-13 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Winter Weather in LEHIGH, PENNSYLVANIA
From 15-JAN-13 22:00:00 to 16-JAN-13 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in NORTHAMPTON, PENNSYLVANIA
From 15-JAN-13 22:00:00 to 16-JAN-13 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in BERKS, PENNSYLVANIA
From 16-JAN-13 01:00:00 to 16-JAN-13 05:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS