November 13–21, 2014 North American winter storm

November 13–21, 2014 North American winter storm

Satellite image of the winter storm on November 17
Type	Extratropical cyclone Winter storm
Formed	November 13, 2014
Dissipated	November 26, 2014
Lowest pressure	961 mb (28.38 inHg)
Maximum snowfall or ice accretion	88 in (223.52 cm)
Areas affected	Pacific Northwest Central United States Eastern United States Northern Mexico Eastern Canada Southern Greenland Iceland
Part of the 2014–15 North American winter

From November 13–21, 2014, a potent winter storm and particularly severe lake-effect snowstorm (given the code name Knife by local governments and colloquially nicknamed "Snowvember") affected the United States, originating from the Pacific Northwest on November 13, which brought copious amounts of lake-effect snow to the Central US and New England from November 15 until November 21, when the system departed the East Coast of the United States. The snowstorm elicited an enormous response from emergency crews and the National Guard, requiring more manpower than any other snowstorm in the history of New York state as it buried cars and stranded thousands of people in their homes in Western New York. Eight months after the storm, the snow's remnants still remained in Buffalo, New York.

The winter storm was associated with the November 2014 North American cold wave. On November 13, an extratropical disturbance developed just off the shore of southern Oregon, at the end of an occluded front. Early on November 14, the system fully moved ashore in the Pacific Northwest, and began bringing snowfall to the region. The winter storm quickly moved southeastward and then northeastward, triggering large amounts of lake-effect snow near the Great Lakes beginning on November 16. On November 16, Lake Erie had a water temperature of 48 °F (9 °C). On November 17, the system reached New England, triggering large amounts of lake-effect snow there as well. The air crossing over the lake by the evening of November 17 was −14 °C (7 °F) at 850 hectopascals at the eastern end of the lake and even colder at its western end; this lapse rate was nearly double that of the dry adiabatic lapse rate and resulted in a very unstable atmosphere at the lower levels. The surface and lower-level winds were also well-aligned with the fetch of Lake Erie, favoring the formation of a long, intense band of lake-effect snow, and varied little over the next several days, keeping the band in place over the same areas for an extended period. The event was briefly interrupted by a low-pressure system with general snowfall passing through on November 20, before reverting to the same synoptic setup as before.