Heavy precipitation overspread the Mid-Atlantic and New England early on December 26. This bout of strengthening occurred as the associated upper-level trough at the 500-millibar levelВ вЂ“ several miles into the atmosphereВ вЂ“ assumed a negative tilt from northwest to southeast. In 12 hours, barometric pressure fell 12 hPa to 996В hPa (29.4В inHg) while the nor'easter accelerated from Georgia to the coast of New Jersey. The low turned toward the northeast by early on December 26 to follow the temperature gradient along the East Coast, at which time the storm underwent the first of two periods of rapid intensification. Precipitation soon blossomed, with heavy snow falling over the Appalachian Mountains by late on December 25. A southerly low-level jet (a localized wind stream in the lower levels of the atmosphere) developed by midday over Mississippi and Alabama, and drifted eastward.

It moved generally eastward over the next day as it crossed the Deep South. The nor'easter originated in a weak area of surface low pressure that formed over northern Texas by December 25. Map of the developing low-pressure system north of the Gulf of Mexico on December 25 Meteorological history The high-pressure area slowly retreated as the storm approached. On December 25 and 26, extensive cold air damming and frontogenesis occurred along the U.S. Д«efore the cyclone's arrival, a 1,033 hPa (30.5 inHg) high-pressure area situated north of New England funneled very cold air into the region the в€’22В вЏ (в€’30В вЊ) air temperature at Albany, New York, on December 25 still holds the record for the city's coldest December temperature. Many of the same areas would be impacted again just days later. A significant storm on December 22вЂ“23 dropped 8 to 24В in (20 to 60В cm) of snow in eastern New York and northern New England, as well as significant freezing rain in southern and eastern New England. December 1969 was a month of active weather throughout the Northeast, with frequent light to moderate snow events preceding the late-month nor'easter. NAO values dropped significantly in the wake of the nor'easter, signaling abnormally cold temperatures during January 1970. North Atlantic Oscillation (NAO) values ranged from weakly negative to weakly positive in the period leading up to the storm, trending more consistently negative in the days surrounding its genesis. The winter of 1969вЂ“1970 continued a long-term El NiГ±o from the previous winter, which featured two significant storms in the Northeastern United States, including the 'Lindsay storm' in February. Wind gusts to 100В mph (160В km/h) and strong waves battered the coastline. In eastern New England, ice jams, poor drainage, and several inches of rain caused flooding that forced people from their homes and submerged roadways. Montreal received 27.5В in (70В cm) of snow in that city's biggest snowstorm on record at the time officials blamed the storm for 15 deaths in Quebec. Throughout the region, the snow and ice-in some cases further weighted by heavy rainfall-caused roofs to cave in. Several inches of glaze ice, accompanied by gale-force winds, caused damage comparable to the aftermath of the 1938 New England hurricane. In central New England, a severe freezing rain event occurred along the boundary between cold air to the west and warmer air to the east. At least 20 fatalities were attributed to the storm in New York and New England. Drifts up to 30В ft (9.1В m) high blocked roadways, isolating some communities and forcing emergency workers to rely on snowmobiles for transportation. Where precipitation remained as snow, accumulations reached 40 inches (100В cm) or more, crippling travel. Warm onshore winds, caused by a storm track close to the shore, allowed precipitation to change to sleet and rain in central and eastern New England. On December 26 and 27, the storm's forward movement slowed to a drift, causing very heavy snow over Upstate New York, Vermont, and southern Quebec. Upon reaching the Eastern Seaboard, the cyclone turned northeastward and intensified into a powerful nor'easter. The storm developed over Texas by December 25 and advanced eastward, spawning over a dozen tornadoes in Louisiana, Georgia, and Florida. The multi-faceted storm system included a tornado outbreak, record snow accumulations, a damaging ice storm, and flooding rains. The December 1969 nor'easter was a strong winter storm that mainly affected the Northeastern United States and southern Quebec between December 25 and December 28, 1969.

Surface weather analysis of the nor'easter, with its track highlighted in red

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