Tuesday, July 3, 2012

What's Behind The Record Heat?

Heat is beating records around the country: the first five months of 2012 have been the hottest on record in the contiguous United States. And that's not including June, when 164 all-time high temperature records were tied or broken around the country, according to government records.
That's unusual, since the most intense heat usually comes in July and August for much of the country, said Jake Crouch, a climate scientist with National Climatic Data Center. For example, only 47 all-time high records were tied or broken in June of last year.
Also, more than 40,000 daily heat records have been broken around the country so far this year, according to the National Oceanic and Atmospheric Administration. Compare that with last year —the ninth warmest on record — when only 25,000 daily records had been set by this date.  
In other words, the heat really is that bad. And behind the records is a set of weather and climate conditions that is keeping the heat locked in over the country, with little respite in sight.
Can't stand the heat
The warm summer follows an unusually warm winter, which was the hottest and driest that the western United States has ever seen since records have been kept, said Jeff Weber, a scientist with the University Corporation for Atmospheric Research in Boulder, Colo.
The heat burning up the country right now is due in part to a persistent high pressure system, also called a heat ridge or dome, which parked itself over the mountain west, and has now shifted east into the Midwest and Southeast. The system is unfortunately stuck in place, Weber said, because of a slowdown of the North Atlantic Oscillation, a climate pattern that pulls weather patterns eastward across the country.
This "blocking" of the Atlantic has caused the jet stream, which normally ferries air from west to east across the United States, to buckle and trap heat in the Midwest and Southeast, Weber told OurAmazingPlanet.

Read more: http://www.ouramazingplanet.com/3130-record-heat-explained.html

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