A modest low pressure system developed along the Gulf Coast on the 16th, with secondary development occurring off the Carolinas by the afternoon. An Arctic air mass was in place over New England as a strong high pressure anchored itself in the Saint Lawrence River Valley. Low pressure occluded early on the 17th and slowly tracked south of New England through the day. An intense band of heavy snow moved north into New Hampshire early in the morning on the 17th and remained nearly stationary into the afternoon. Snowfall rates of 4 to 6 inches per hour and total amounts pushing 3 to 4 feet were observed at the peak of the event. Dry air and a deamplifying upper trough limited the northward push of heavy snow, leaving a sharp gradient on the poleward edge of accumulating snowfall. Despite roughly 12 hours of snowfall, some observed amounts challenged 24 hour state snowfall records.

Winter Storm in NORTHERN GRAFTON, NEW HAMPSHIRE
From 17-DEC-20 04:00:00 to 17-DEC-20 15:00:00 (EST-5)
Reported by: Trained Spotter

Snow began before sunrise on the 17th. The heaviest snowfall moved into areas south of Franconia Notch by mid morning. Snowfall rates exceeded inch per hour in the heaviest snow, but dry air to the north and weakening lift with increasing latitude left a sharp gradient in storm totals north of the notches. Snowfall totals ranged from 12 to 18 inches in the southern White Mountains westward to the Connecticut River, but only 3 to 6 inches north of the notches to Littleton.

Winter Storm in NORTHERN CARROLL, NEW HAMPSHIRE
From 17-DEC-20 04:00:00 to 17-DEC-20 15:00:00 (EST-5)
Reported by: Trained Spotter

Snow began before sunrise on the 17th. The heaviest snowfall moved into areas south of Crawford Notch by mid morning. Snowfall rates exceeded inch per hour in the heaviest snow, but dry air to the north and weakening lift with increasing latitude left a sharp gradient in storm totals across the White Mountains. Snowfall totals ranged from 12 to 18 inches in the southern White Mountains, but only 4 to 6 inches moving north on Route 16.

Winter Storm in SOUTHERN GRAFTON, NEW HAMPSHIRE
From 17-DEC-20 01:00:00 to 17-DEC-20 14:00:00 (EST-5)
Reported by: Trained Spotter

Snow began after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved into the area. As the band became nearly stationary over southern portions of Grafton County snowfall rates between 4 and 6 inches per hour were observed. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals were generally between 18 and 24 inches, with locally higher amounts approaching 3 feet in far southern Grafton County.

Winter Storm in STRAFFORD, NEW HAMPSHIRE
From 17-DEC-20 02:00:00 to 17-DEC-20 15:00:00 (EST-5)
Reported by: Trained Spotter

Snow began early in the morning on the 17th. Snow quickly became heavy as an intense band of snow moved into the area. As the band became nearly stationary snowfall rates in excess of 4 inches per hour were observed. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals ranged between 8 near Great Bay to nearly 30 inches in the Moose Mountains.

Winter Storm in CHESHIRE, NEW HAMPSHIRE
From 17-DEC-20 00:00:00 to 17-DEC-20 13:00:00 (EST-5)
Reported by: Trained Spotter

Snow began just after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved through the area. While the band became stationary north of the area, as it moved through snowfall rates of 3 to 4 inches per hour were observed. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals ranged from 12 to 24 inches.

Winter Storm in WESTERN AND CENTRAL HILLSBOROUGH, NEW HAMPSHIRE
From 17-DEC-20 00:00:00 to 17-DEC-20 14:00:00 (EST-5)
Reported by: Trained Spotter

Snow began just after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved through the area. While the band became stationary north of the area, as it moved through snowfall rates of 3 to 4 inches per hour were observed. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals ranged from 12 inches near the Massachusetts border to 24 inches north of the Monadnocks.

Winter Storm in EASTERN HILLSBOROUGH, NEW HAMPSHIRE
From 17-DEC-20 00:00:00 to 17-DEC-20 14:00:00 (EST-5)
Reported by: Trained Spotter

Snow began just after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved through the area. While the band became stationary north of the area, as it moved through snowfall rates of 3 to 4 inches per hour were observed. During mid morning hours an area of persistent subsidence between two more intense areas of lift produced lower snowfall rates and accumulations. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals ranged from 8 to 14 inches.

Winter Storm in INTERIOR ROCKINGHAM, NEW HAMPSHIRE
From 17-DEC-20 00:00:00 to 17-DEC-20 15:00:00 (EST-5)
Reported by: Trained Spotter

Snow began just after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved through the area. While the band became stationary north of the area, as it moved through snowfall rates of 3 to 4 inches per hour were observed. During mid morning hours an area of persistent subsidence between two more intense areas of lift produced lower snowfall rates and accumulations. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals ranged from 8 to 15 inches.

Winter Storm in COASTAL ROCKINGHAM, NEW HAMPSHIRE
From 17-DEC-20 00:00:00 to 17-DEC-20 15:00:00 (EST-5)
Reported by: Trained Spotter

Snow began just after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved through the area. While the band became stationary north of the Seacoast, as it moved through snowfall rates of 3 to 4 inches per hour were observed. During mid morning hours an area of persistent subsidence between two more intense areas of lift produced lower snowfall rates and accumulations. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals ranged from 8 to 12 inches.

Winter Storm in SULLIVAN, NEW HAMPSHIRE
From 17-DEC-20 00:00:00 to 17-DEC-20 14:00:00 (EST-5)
Reported by: Trained Spotter

Snow began just after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved into the area. As the band became nearly stationary snowfall rates of 4 to 6 inches per hour for several hours were observed, leading to extremely dangerous travel conditions. Lightning strikes were also observed during the most intense snowfall. A weakening trough aloft quickly brought an end to snow by mid afternoon. The high snow ratio of the storm allowed snowfall totals to generally exceeded 24 inches across Sullivan County. There were several reports in excess of 40 inches, breaking the county snowfall record and challenging the state record for a 24 hour snowfall.

Winter Storm in MERRIMACK, NEW HAMPSHIRE
From 17-DEC-20 01:00:00 to 17-DEC-20 14:00:00 (EST-5)
Reported by: Trained Spotter

Snow began just after midnight on the 17th. Snow quickly became heavy as an intense band of snow moved into the area. As the band became nearly stationary snowfall rates of 4 to 6 inches per hour for several hours were observed, leading to extremely dangerous travel conditions. Lightning strikes were also observed during the most intense snowfall. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals were generally between 18 and 24 inches, with locally 3 to 4 feet under the center of the snowband due to high snow ratios. There were several reports in excess of 40 inches, breaking the county snow record and challenging the state record for a 24 hour snowfall.

Winter Storm in BELKNAP, NEW HAMPSHIRE
From 17-DEC-20 02:00:00 to 17-DEC-20 14:00:00 (EST-5)
Reported by: Trained Spotter

Snow began early in the morning on the 17th. Snow quickly became heavy as an intense band of snow moved into the area. As the band became nearly stationary snowfall rates of 4 to 6 inches per hour for several hours were observed, leading to extremely dangerous travel conditions. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals were generally between 18 and 24 inches, with locally up to 3 feet under the center of the snowband due to high snow ratios.  The 24hr county snowfall record was broken.

Winter Storm in SOUTHERN CARROLL, NEW HAMPSHIRE
From 17-DEC-20 03:00:00 to 17-DEC-20 15:00:00 (EST-5)
Reported by: Trained Spotter

Snow began before sunrise on the 17th. Snow quickly became heavy as an intense band of snow moved into the area. As the band became nearly stationary over the Ossipee Mountains towards Lake Winnipesaukee snowfall rates approaching 4 inches per hour were observed, leading to dangerous travel conditions. A weakening trough aloft quickly brought an end to snow by mid afternoon. Snowfall totals were generally between 18 and 24 inches, with locally higher amounts approaching 30 inches in far southern Carroll County due to the high snow ratios.