Polar Vortex Is Back: Coldest of the Cold En Route to U.S. (Wind maps and world circulation) [View all]
The polar vortex is back, and for many suffering through an already frigid winter, the Arctic air barreling into the lower 48 states may be the coldest of the cold yet.
Temperatures may plunge well below zero in the Upper Midwest, and could potentially last as long as three days in some areas. Cities such as Chicago, Minneapolis, and Madison are already enduring extreme cold, with two consecutive days of subzero high temperatures expected. In addition, a rare snow and ice storm is slated to develop along the Gulf Coast on Tuesday and Wednesday. Computer model projections show the potential for more than 6 inches of snow to fall in parts of the Southeast, particularly in Southeast South Carolina, Georgia, and North Carolina, areas that are not accustomed to such heavy snowfall and ice.
Visualization of surface winds (lines and black arrows) and temperatures (shaded colors) on Monday morning, as the latest Arctic blast swept from the Midwest to the South and East.
Credit: earth.nullschool.net.
The frigid temperatures in the Central and Eastern U.S. come courtesy of a jet stream pattern that has kept the door to the Arctic, which is the Northern Hemisphere’s freezer, wide open, allowing dangerously cold air to repeatedly move southward into the lower 48 states in distinct waves.
As happened in early January, the now infamous polar vortex has something to do with the latest cold snap, with its southernmost extent clipping the northern tier of the U.S.
The persistence of the cold during January has set the month on course to be the second coldest winter month in the contiguous U.S. since December 2000, coming up about a degree shy of the monthly average temperature in January 2011, according to Ryan Maue of WeatherBell Analytics, a private weather forecasting firm.
Visualization of wind speed and direction in the lower stratosphere, looking from the top of the Northern Hemisphere down. The polar vortex is highlighted within the black rectangle, with its circulation extending south above the U.S.
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http://www.climatecentral.org/news/polar-vortex-is-back-coldest-of-cold-en-route-to-us-17003
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