November 2014 North American cold wave

November 2014 North American cold wave

A temperature map of the frigid conditions on November 17, 2014.
Formed	November 8, 2014
Dissipated	November 23, 2014
Lowest pressure	920 hPa (27 inHg) (2014 Bering Sea cyclone)
Damage	Unknown
Areas affected	Canada Contiguous United States Northern Mexico
Part of the 2014–15 North American winter

The November 2014 North American cold wave was an extreme weather event that occurred across most of Canada and the contiguous United States, including parts of the Western United States up to western California. One of the first events of the winter, the cold wave was caused by the northward movement of an extremely powerful bomb cyclone associated with Typhoon Nuri's remnant, which shifted the jet stream far northward, creating an omega block pattern. This allowed a piece of the polar vortex to advance southward into the Central and Eastern United States, bringing record-cold temperatures to much of the region. In contrast, Alaska experienced above-average temperatures.

This was the worst cold wave that the North American region had experienced since an earlier cold wave in early 2014. The cold wave was expected to last for a few weeks, extending at least until American Thanksgiving. Although the Omega Block broke down on November 20, due to a powerful storm moving into the Gulf of Alaska, frigid conditions continued to persist across much of the United States. There was also concern among some meteorologists that another cold wave or abnormally cold trend might persist throughout the winter of 2014–15, the chances of which were "above average." On November 23, a warming trend primarily in the Eastern United States brought an end to the cold wave; however, below-average temperatures were forecast to return to the Midwest by November 24. Despite the development of a second cold wave, it ended on December 6, when a ridge of high pressure brought above-average temperatures to the region, especially in the Central United States.

On November 8, the northward movement of a cyclone associated with Typhoon Nuri shifted the jet stream far to the north, creating an omega block pattern, which allowed a fragment of the polar vortex to descend from Arctic region into lower Canada and the Eastern United States, affecting up to 200 million people with colder-than-normal temperatures and early snowstorms. Although the Omega block broke down on November 20, a powerful storm brought more frigid temperatures. The wave ended on December 6 when an area of high pressure moved in.