Winter Storm in Southern Carroll, New Hampshire

Snow began in the afternoon and quickly became moderate to heavy in the late afternoon. By late evening warmer air aloft changed precipitation to a mix of snow and sleet. Southeast flow allowed some upslope enhancement of precipitation in the higher terrain of the southern White Mountains. The mix continued into the early morning hours when precipitation quickly ended from west to east. Combined snow and sleet accumulations ranged from 5 to 7 inches.

Early on the 12th surface low pressure formed over the southern Plains, lifting north and strengthening into the Great Lakes. By the evening of the 12th low pressure had deepened to around 995 mb. A warm front extended to the east of low pressure, held in place by a 1038 mb high pressure centered over Quebec. The strong low pressure in the Great Lakes and the exit region of a greater than 100 knot jet streak over the Canadian Maritimes was supporting strong and broad warm air advection over the Northeast. With cold and dry air in place precipitation initially began as snow across northern New England. Secondary low pressure developed off the Mid Atlantic coast and strengthened south of Long Island, ensuring that low level cold air remained in place. Aloft warmer air surged northward, eventually changing precipitation to sleet and freezing rain over much of New Hampshire. Early on the morning of the 13th dry air aloft brought a quick end to precipitation from west to east.