January 11, 2017

Lake effect snows like the events that buried parts of Michigan and New York in mid-December might actually become more common as the U.S. climate warms, at least for a while. This post explains the paradox.

December 29, 2016

As cold air filtered into the United States over the Great Lakes, the lake effect snow machine turned on burying nearby locations.

September 16, 2016

The Northwest Passage across the Canadian Arctic opened once again in 2016 as sea ice reached its second lowest extent on record.

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.