East's early cold: 'Greenland Block' lets Arctic air slip to Deep South
The depth of this winter's chill will depend on the 'Greenland Block' – a high-pressure bulldozer that holds up warmer winds from the equator and steers Arctic air toward the Deep South.
The kids funneling into Atlanta's Toomer Elementary School Tuesday morning had just one thing to say from under their pulled-down hats: BRRRR!
Already producing one of the earliest hard freezes in recent years, the Arctic cold snap that's toe-chilling the East Coast is a variant of last year's deep chill that hit the South in January, stunning hundreds of Florida sea turtles midswim and causing iguanas to drop out of palm trees.
In essence, the high-pressure system is holding up warmer winds from the equator and steering Arctic air down its flanks, creating a dramatic zig-zag pattern in rivers of air that normally flow more parallel to the equator.
That, in turns, creates more regional phenomena like the "Alberta clipper" cold front, which blew into the Deep South over the weekend. The Greenland Block, in other words, is the X factor that will determine the depth and extent of this year's winter for millions of Americans.
"For the foreseeable future, many residents of the Eastern US will be living in a world so cold (and windy!) as temperatures are likely to be frozen in time as if the depths of January," writes Foots Forecast, a consortium of high school amateur meteorologists.
The deep freeze has already hit many Americans. This weekend, the Drudge Report featured a story about bundled-up Atlantans lining up for heating assistance, with some likening the scene to Depression-era soup lines. Schools are closed Tuesday in six western North Carolina counties.
Normally balmy Fort Lauderdale, Fla., broke a 169-year-old record Tuesday, when temperatures dipped into the low 40s and wind chills dropped the "real feel" of the bite into the 20s.
Florida orange and strawberry growers, who faced million-dollar losses after an unusual cold spell in January, are concerned, with some now busy spraying their up-and-coming crops with water, which forms an icy shell that protects the fruit. Some Florida farmers lost 30 percent of their crop to the January deep-freeze.
Global warming experts have warned that 2010 could become one of warmest years on record. And Vaughn Smith, a National Weather Service meteorologist in Peachtree City, Ga., says the long-term prognosis for much of the South is a wetter and warmer winter than last year. (To put everything in context, if you see "sneaux" in New Orleans on Wednesday, it's fake stuff shipped in for a winter event at Loyola University.)
Though global warming has its share of skeptics, weather variability like the current East Coast freeze may be a result of a broader warming trend, many scientists contend.
The early cold snap "shows that the climate is becoming more dynamic, and thus large shifts in the wind patterns are possible – in this case, sub-tropical air being trapped further south than usual," Mark Maslin, a professor at University College London, told Britain's Telegraph.
Indeed, the Greenland Block isn't just freezing nosehairs in the US, but is also largely responsible for the massive early snowfall in Britain and record cold temperatures sweeping across Scandinavia.
"As the trough digs south, arctic air is no longer locked in the ... well ... arctic," explains weather.com. "It is free to spill away from the cold dungeon."