"Wavenumber 6 Pattern" Promises To Bring Record Melt To Greenland, Snow To Northeast US This Week
During the course of the next 10 days or more, the weather pattern across the Northern Hemisphere will feature an undulating, wavy jet stream that will be stuck in place, with storms backed up like cars on an interstate highway at rush hour.
Large dips in the jet stream, which is the narrow current of fast-flowing air at high altitudes that plays a crucial role in creating and steering weather systems, will lead to prolonged periods of cool, wet weather across the West and East Coasts of the U.S. Snow is even possible in parts of the Northeast U.S. during the second week of May. (Seriously.)
At the same time, unseasonably mild weather is projected to envelop Greenland and parts of Canada, potentially initiating an early start to the ice melt season there and melting remaining snow cover in Alberta and Nunavut.
And this is just part of the story. Extremes will also occur further east, across Europe, Russia, and eastern Asia.
EDIT
http://mashable.com/2017/05/03/extreme-weather-pattern-early-may-wavenumber-6/#OTQjtTFogmqJ