The winter the Arctic shifted south
Last week, Chicagoans were treated to one of that city's worst blizzards of all time. Featuring several rounds of thundersnow - a relatively rare phenomena that has been in abundant supply this winter, making appearances in D.C., New York, Boston, and now Chicago - winds gusting to between 50 and 70 miles per hour, and upwards of 20 inches of snowfall, the storm paralyzed one of the most battle tested cities for dealing with wintry onslaughts.
The eerie sight of hundreds of stranded and abandoned cars along Lakeshore Drive, a scene straight out of the global warming disaster movie "The Day After Tomorrow," must've made New York City mayor Michael Bloomberg, whose administration was roundly criticized for botching cleanup efforts after the "Boxing Day Blizzard" in December, feel satisfied that it's not just the Big Apple that can be snarled by a snowstorm.
True, the massive storm system that brought snow, strong winds, and icy conditions to areas from New Mexico to Maine, largely spared the D.C. area from its most significant impacts, disappointing snow lovers - as have other major storms this year (well except for that one...).
However, between this blizzard, and the parade of east coast snowstorms that have dropped so much snow on the northeast that local news coverage in southern New England of late has been dominated by reports of roof collapses, this is certainly shaping up to be a winter to remember.
Yet for a key region of the globe, it's actually proving to be a remarkably warm winter so far, which, believe it or not, may help explain why it's been so cold and snowy in the U.S.
Many cities, including Boston, Hartford, New York, and Philadelphia have already surpassed their typical annual snowfall totals, and officials in several cities and towns in southern New England are contemplating dumping additional snow directly into waterways, despite the environmental damage that may cause.
The snowstorms have also been accompanied by outbreaks of very cold air. According to statistics compiled by HAMweather, between January 30 and Feb. 5, 489 low temperature records were set in the U.S., along with 792 records for the lowest high temperature. These records include a frigid -36 degree low temperature at Steamboat Springs, Colorado on Feb. 3 (I wouldn't advise skiing in such conditions), -42 F in Havre City Montana, and -21 F near Hamilton, Missouri. Other records were set from Texas to Massachusetts.
Such cold weather records dwarfed warm records during the same period, which goes against a long-running trend.
There's a reason the weather has felt more typical of the Arctic than of the lower-48: the Arctic conditions have been on an extended sojourn here, having left the far north sometime in December. The Arctic itself was relatively mild in January. In fact, the National Snow and Ice Data Center announced that Arctic sea ice extent during January reached the lowest level on record for the month, with unusually low ice extent noted in Hudson Bay, Hudson Strait, and Davis Strait.
"Normally, these areas freeze over by late November, but this year Hudson Bay did not completely freeze over until mid-January," NSIDC reported. "The Labrador Sea remains largely ice free."
According to NSIDC, Arctic air temperatures and sea ice conditions were significantly affected by the configuration of a natural climate pattern known as the Arctic Oscillation, or AO. The AO, which is closely related to the North Atlantic Oscillation or NAO, refers to opposing pressure patterns in middle and high northern latitudes.
When the AO is in a "negative phase," there is a region with relatively high pressure located over the polar region, and lower pressure at the midlatiudes. In a "positive phase", the pattern is reversed, with lower pressure in the polar region, and higher pressure in the midlatitudes.
The AO, as well as the NAO, significantly influence the extent to which cold air gets pushed south into North America and Europe, as well as the predominant storm track.
As this web page details, "In the positive phase, frigid winter air does not extend as far into the middle of North America as it would during the negative phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual. Weather patterns in the negative phase are in general "opposite" to those of the positive phase..."
Ah, if only we were in Nunavut
During much of this winter so far, with the exception of late January and early February, the AO and the NAO were in an extremely negative phase. This helped drive cold air into the U.S. and favored a storm track up the northeastern coastline. While these storms taunted D.C. snow-lovers and plastered New York and Boston with heavy snow, they swept mild air into Greenland and parts of northeastern Canada. An unusually strong blocking pattern was also in place over Greenland, which helped maintain this storm track week after week.
To put this picture into even sharper focus, let's take a look at Coral Harbour, located at the northwest corner of Hudson Bay in the province of Nunavut. On a typical mid-January day, the town drops to a low of -34°C (-29.2°F) and reaches a high of just -26°C (-14.8°F). Compare that to what Coral Harbour actually experienced in the first twelve days of January 2011, as reported by Environment Canada.
- After New Year's Day, the town went 11 days without getting down to its average daily high.
- On the 6th of the month, the low temperature was -3.7°C (25.3°F). That's a remarkable 30°C (54°F) above average. [emphasis added]
- On both the 5th and 6th, Coral Harbor inched above the freezing mark. Before this year, temperatures above 0°C (32°F) had never been recorded in the entire three months of January, February, and March.
(Conditions in Coral Harbour have since cooled down considerably, related to the flipping of the Arctic Oscillation back into a positive phase).
Climate scientists are studying the interaction between the diminishing sea ice cover in the Arctic and changes to air circulation patterns in the northern hemisphere. Although this is far from an open and shut case, some studies show there may be a connection between the diminishing sea ice cover, which allows more heat to escape into the atmosphere, may be altering wintertime weather patterns in such a way that harsh winters are becoming more likely in parts of the U.S. and Europe.
If additional studies bolster this finding, and such trends continue, it would have to be one of the most paradoxical manifestations of climate change. Here we have an Arctic region that is being literally transformed by warming and melting ice, and yet in the northern midlatitudes, that translates to colder and snowier winters? How strange.
Then again, stranger things have happened. Just ask residents of Coral Harbour, Nunavut.
The views expressed here are the author's alone and do not represent any position of the Washington Post, its news staff or the Capital Weather Gang.
| February 7, 2011; 10:20 AM ET
Categories: Climate Change, Freedman, Latest, News & Notes, Science
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