March 11, 2016

For the third winter in a row, temperatures were well above normal for much of Alaska, leaving Alaskans to wonder, where's winter?

February 24, 2015

A stalled atmospheric set-up has made Boston and surrounding areas in the Northeast the most popular truck stop for storms travelling the atmospheric highway known as the jet stream. And stop they have, like a caravan of tractor-trailers idling in a rest stop parking lot.

September 16, 2014

Temperature extremes have been pretty unusual across the United States so far in 2014. Looking back over this time period quickly reveals at least part of what was going on: the polar jet stream got into a serious rut.

August 29, 2014

Never in the historical record have such large areas of the country experienced such radically different temperature extremes as they have so far in 2014.

February 26, 2014

Persistent cold temperatures in the Midwest this winter almost completely frozen over many of the Great Lakes. The Great Lakes Environmental Research Laboratory (GLERL) reported that 88 percent of the Great Lakes were frozen as of mid-February.

January 20, 2014

The Arctic Oscillation describes simultaneous, geographically “choreographed” shifts in multiple features of the polar vortex: air pressure, temperature, and the location and strength of the jet stream. They all follow the hemisphere-wide oscillation of atmospheric mass back and forth between the Arctic and the middle latitudes, sort of like water sloshing in a bowl.

January 10, 2014

A few days of unusually cold weather in the U.S. and Canada aren't a sign that a century-or-more trend of rising global surface temperatures has reversed itself. In fact, the cold wasn't even all that widespread for the Northern Hemisphere.

January 8, 2014

Meteorologists have known for years that the pattern of the polar vortex determines how much cold air escapes from the Arctic and makes its way to the U.S. during the winter. Climate scientists are wondering if a warmer Arctic could explain its odd behavior in recent years.

April 5, 2011

Natural climate phenomena—the North Atlantic Oscillation & La Niña—can explain much of this winter's temperature patterns across North America.