What are the leading influences on North America winter 2018-19 climate? Typical of climate patterns of recent years ENSO has a diminished role despite presence of an El Nino likely to gain strength. The lead modes of climate influence are the warmer than normal Pacific Ocean in the tropics and northern latitudes near the Dateline and the warmer than normal Norwegian Sea. The accumulative effect of an inactive sun may also be helping to induce increased cold risk.
Except for March every month of 2018 so far has produced an exceptional positive phase of the North Atlantic oscillation. Implied is residence of a strong polar vortex in the higher latitudes biased toward northeast Canada and Greenland much of this year. That pattern is about to change abruptly as a high latitide/high pressure ridge evolves over Greenland which will affect northern hemisphere mid-latitude climate the last third of November.
El Nino warming of the East Pacific is with us but the atmosphere is not reacting. The result? Near-record snow cover across North America and an incoming cold U.S. pattern. Why is the coupling of the atmosphere to El Nino warming NOT occurring?
An intra-seasonal migrating tropical feature known as the Madden Julian oscillation representative of a massive area of tropical thunderstorm activity was tapped by a low pressure system south of France on November 2 making the attendant storm much stronger and causing widespread damage including 17 deaths across Italy.