A major winter storm affected the mid-Atlantic from January 31 to February 2, 2021. Low pressure tracking out of the Ohio Valley weakened as it moved slowly eastward on the 31st. Meanwhile, as that low weakened, secondary low pressure began to develop off the coast of the Carolinas and tracked northward, just off the mid-Atlantic coast. The low steadily intensified as it moved up the coast in a classic ���Miller B��� storm evolution. The result was a significant and unusually long duration winter storm. Overrunning precipitation associated with the initial low over the Ohio Valley impacted the region on the 31st. A cold antecedent air mass allowed most of this precipitation to fall as snow. This produced widespread snow accumulation, though the overrunning precipitation was mostly of the light to moderate variety. Some areas experienced a lull in precipitation on the overnight of the 31st as the secondary low began to develop and a dry slot overspread a large area. In addition, a surge of warmer air both at the surface and aloft caused precipitation to change to sleet or rain in some areas, especially locations farthest south and east such as the Delmarva peninsula and southern New Jersey. However, as the secondary low strengthened, heavy precipitation developed on February 1, with intense banding and areas of extreme snowfall rates of 2 to 4 inches per hour in northern New Jersey and portions of eastern Pennsylvania. Precipitation eventually turned back to snow all the way to the coastline as colder air was drawn in from the north. The secondary low pressure nearly stalled off the mid-Atlantic coast, causing snow to continue into February 2, although by then snowfall rates were much lighter and additional accumulation was limited. Areas where precipitation remained all snow and that experienced the heavy banding saw extreme snowfall totals, with isolated amounts of near 3 feet of snow and a fairly widespread swath of in excess of 2 feet. Snow flurries even continued into February 3 around the backside of the slow moving low���s large circulation, before it finally departed and brought an end to one of the region���s most notable snow events in years.

Winter Storm in LEHIGH, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Snow began in the county on January 31. It became heavy on February 1 as intense banding developed over the Lehigh Valley. Lighter snow continued into February 2 before the storm finally departed. By the end of the event, a report was received from Coopersburg of 31.0 inches of snow. Numerous other reports of 24 to 30 inches of snow were received in the major winter storm. The Lehigh Valley International Airport recorded a storm total of 27.3 inches of snow.
A 67 year old woman with Alzheimer's died of hypothermia in Allentown when she wandered outside during the storm.

Winter Storm in MONROE, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow began across the county on January 31 and continued into the new month. Snow became heavy on February 1 as intense banding developed, with lighter snow continuing into February 2. By the end of the event, a trained spotter in Mount Pocono had amassed a storm total snowfall of 36.9 inches, which was also the highest storm total snow amount reported in this storm. A widespread 20 to 30 inches of snow fell throughout the county in one of the area's largest winter storms on record.

Winter Storm in CARBON, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow began on January 31 and continued into the new month. Snow became heavy at times on February 1 as intense banding developed, with lighter snow continuing into February 2. By the time the storm pulled away, a trained spotter in Towamensing Twp had recorded a storm total of 26.0 inches of snow, with numerous other reports of 18 to 24 inches of snow throughout the county from this long duration winter storm.

Winter Storm in NORTHAMPTON, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Snow began in the county on January 31 and continued into the new month. Snow became heavy on February 1 as intense banding developed, with Northampton County experiencing some of the heaviest snowfall rates. Some light snow continued into February 2. By the end of the storm, a report was received from Nazareth of 36.1 inches of snow. Numerous other reports of 24 to 32 inches were received in one of the largest winter storms on record for the area.

Winter Storm in BERKS, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow began in the county on January 31 and continued into the new month. Snow became heavy on February 1 as intense banding developed, with lighter snow continuing into February 2. By the end of the storm, trained spotters in both Fleetwood and Mertztown reported storm totals of 26.0 inches of snow. Numerous other reports of 18 to 24 inch storm totals were reported from this major winter storm.

Winter Storm in UPPER BUCKS, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Snow began on January 31 and continued into the new month. Snow became heavy on February 1 as intense banding developed, with lighter snow continuing into February 2. A COOP observer near Springtown measured a storm total of 32.0 inches of snow, though most reports in the area were in the range of 15 to 22 inches.

Winter Storm in LOWER BUCKS, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow began on January 31. Precipitation continued into February 1. It decreased in intensity and also mixed with sleet for a time before changing back to snow later on February 1, when it also became heavy at times. A storm total snowfall of 13.0 inches was reported by a trained spotter in Langhorne, with 8 to 14 inches of snow reported across Lower Bucks from the long duration storm.

Winter Storm in WESTERN MONTGOMERY, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 14:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Snow began on January 31. Precipitation continued into February 1. It decreased in intensity and also mixed with sleet for a time before changing back to snow later on February 1, when it also became heavy at times. Lighter snow continued into February 2. By the end of the event, a storm total snowfall of 15.0 inches was reported in Trappe. Numerous additional reports of 10 to 15 inches of snow were received.

Winter Storm in EASTERN MONTGOMERY, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Snow began on January 31. Precipitation continued into February 1. It decreased in intensity and also mixed with sleet for a time before changing back to snow later on February 1, when it also became heavy at times. Lighter snow continued into February 2. By the end of the event, a storm total snowfall of 15.1 inches was reported by a CoCoRaHS observer near Ambler. Numerous other reports of 10 to 15 inches of snow were received.

Winter Storm in WESTERN CHESTER, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow began on January 31. Precipitation continued into February 1. It decreased in intensity and also mixed with sleet for a time before changing back to snow later on February 1, when it also became heavy at times. Lighter snow continued into February 2. By the end of the event, a trained spotter in East Nantmeal Twp reported a storm total of 16.6 inches of snow. Numerous other snowfall reports of 10 to 15 inches were received from the long duration winter storm.

Winter Storm in EASTERN CHESTER, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Snow began on January 31. Precipitation continued into February 1. It decreased in intensity and also mixed with sleet for a time before changing back to snow later on February 1, when it also became heavy at times. Lighter snow continued into February 2. By the end of the event, a CoCoRaHS observer near West Chester reported a storm total snowfall of 10.2 inches. Numerous other reports of 6 to 10 inches of snow were received from the area.

Winter Storm in PHILADELPHIA, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow began on January 31. Precipitation continued into February 1. It decreased in intensity and also mixed with sleet for a time before changing back to snow later on February 1, when it also became heavy at times. Lighter snow continued into February 2. A storm total snowfall of 10.0 inches was reported by a trained spotter in Fox Chase. Several other 6 to 10 inch snowfall reports were received. Philadelphia International Airport measured 8.1 inches of snow from the long duration winter storm.

Winter Storm in DELAWARE, PENNSYLVANIA
From 01-FEB-21 00:00:00 to 02-FEB-21 13:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Snow began on January 31. Precipitation continued into February 1. It decreased in intensity and also mixed with sleet for a time before changing back to snow later on February 1, when it also became heavy at times. Lighter snow continued into February 2. A trained spotter in Villanova reported a storm total of 9.0 inches of snow. Several other reports of 6 to 9 inch storm totals were received.