Polar vortex splits in two in winter, sucks up methane and carries it at high altitude to other regions of North America

Because the density of methane is slightly more than half of that of the air (Engineering Toolbox, 2011), it must rise upwards into the middle troposphere along a gradual curve the trend of which will be determined by Corioli's force as the cold heavy surface Arctic air spirals out in a clockwise fashion from the northern latitudes (NSIDC, 2011b). Above 5 km in the mid to upper Arctic troposphere and stratosphere (ca 30 km height), there is a perpetual anticlockwise (cyclonic) massive vortex circulation, which is asymmetric often breaking into two units separated by a low pressure trough above the E of North America (NSIDC 2011a).

In winter the giant anticlockwise spiraling stratospheric vortex generated over the central Arctic ocean may become irregularly shaped, breaking into two separate spirals (the vortexes are like two giant tornadoes) centered over the northern Siberian Arctic offshore shelf (which is the region of present day massive methane leakage from disassociating submarine methane hydrates) and the Beaufort Sea - Northern Canada and the United States. The Arctic Ocean floor sourced methane must be sucked up into the stratosphere by these two giant tornado systems that are rotating anticlockwise in sympathy with the Earth. The high altitude methane is subsequently carried SW over Russia, Europe and into the Atlantic by the variably shaped anticlockwise rotating stratospheric vortex at some 30 km altitude, while a second vortex developed over Canada will similarly carry methane over the continental United States.

See this animation on NASA 2011 (6.59 MB download):
http://earthobservatory.nasa.gov/images/imagerecords/36000/36972/npole_gmao_200901-02.mov
At the time this Polar stratospheric vortex developed in late January to early February in 2009, Arctic stratospheric wind and temperature patterns changed dramatically, as illustrated by the images and text at
Stratosphere Influences Winter Weather.

From: http://arctic-news.blogspot.com/p/seismic-activity.html