By: Andrew Freedman
Published: January 8,2014
But in general, this Arctic outbreak, courtesy of a huge chunk of the polar vortex that the jet stream temporarily dislodged from the Arctic, is bringing the coldest temperatures in 20 to 30 years to many areas of the Midwest, Ohio Valley, Deep South, and the eastern seaboard.
Some of the most severe cold has affected the Midwest, from Minnesota to Illinois and east to Michigan. Chicago set a record for the 7th coldest noontime temperature since 1930, with a temperature of just -14°F at midday on Monday. But the city did not set any all-time cold records.
While the cold temperatures have been unusual and even deadly, climate data shows that intense cold such as this event is now occurring far less frequently in the continental U.S. than it used to.
Climate Central
The trend in frigid nights in St. Louis from the 1970s to the most
recent decade. The yellow line in the graph above indicates the linear
trend since 1970.
Climate Central calculated the number of nights below a specific temperature threshold for dozens of U.S. cities based on the local climatology and current weather conditions.
The calculations encompass the entire winter season, and show that overall there is a downward trend in the number of extreme cold nights like we’re currently experiencing – although there are variations in a few cities.
This trend is consistent with climate studies showing that overall, winters across the contiguous U.S. have warmed by .61°F per decade since 1970, and every region has warmed at least somewhat over that time.
Winters have also warmed over a longer period of record, but the fastest warming has taken place during the past few decades. In addition, the fastest warming has taken place at night, rather than during the day, which is consistent with climate change projections.
Climate Central
The trend in frigid nights in Minneapolis-St. Paul from the 1970s to
the most recent decade. The yellow line indicates the linear trend since
1970.
The calculations run from July through June of the following year, so that we wouldn't break up the winter season.
In Detroit in the 1970s, there were an average of 7.9 nights with temperatures below zero degrees. But now, that number is closer to 2 nights. And in Washington D.C., the number of nights with a low of 20 or below was 13.5 in the 1970s, but was closer to 8.3 in the past decade. The overnight low at Reagan National Airport on Jan. 7 was 6°F.
And in St. Louis, the 1970s featured an average of 3.8 nights with a low of 0°F or below, yet in the past decade, the average for such frigid nights fell to zero.
A Climate Central analysis released in February 2013 found that the states with the coldest winters have been warming the fastest, including states hard hit by the current cold snap. The top 5 fastest-warming states, the analysis found, were Minnesota, North Dakota, Wisconsin, Vermont and South Dakota.
Climate Central
The trend in frigid nights in Detroit from the 1970s to the most
recent decade. The yellow line indicates the linear trend since 1970
In fact, it has now been 345 consecutive months and counting where global average temperatures have been above the average for the last century (as of November, that is — numbers for December have not yet been finalized).
And there is ongoing research that suggests that rapid Arctic warming, which has been linked to human-caused global warming, may be creating more amplified weather patterns like the one that we are currently seeing, with sharp curves in the jet stream steering weather systems in unusual ways.
If that hypothesis is true, we could actually experience more extreme cold snaps, even as the planet continues to warm.
Related Content from Climate Central
- Arctic Outbreak: When the North Pole Came to Ohio
- Coldest Air in Decades Clearing Customs, Entering U.S.
- Polar Vortex in U.S. May be Example of Global Warming
Two people help a stranded motorist up
snow-covered exit ramp on I-44 Sunday, Jan. 5, 2014, in St. Louis. (AP
Photo/Jeff Roberson)
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