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Meteorological Synopsis

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The evolution of a record-breaking snowstorm across the Southeast United States first began with the progression of a strong cold front across the region on December 21–22.[1] Behind this front, an abnormally strong 1054 mb (31.13 inHg) surface area of high pressure slid southward across the Great Plains.[2] In the upper levels of the atmosphere, cross polar flow—expansive troughiness that extends from Siberia across the North Pole and into the East Coast of the United States—became established.[1] The combination of these two events led to a record-breaking arctic outbreak across much of the United States in late December. Temperatures ranged from near freezing as far south as Florida and the Gulf Coast, to teens and twenties across the Southeast, to well below zero across the Midwest.[1][2] Although weather forecast offices across the Carolinas were monitoring the progress of an upper-level disturbance near the Colorado–New Mexico border headed southeast, initial indications were that the strong arctic high would prevent precipitation and only frigid temperatures would be observed.[1]

By late on December 22, the upper-level disturbance tracked across central Texas and acted to amplify the larger upper-level trough across the East Coast of the United States. Southwesterly winds became established across portions of the Southeast, leading to an expansive mass of rainfall across central Florida and wintry precipitation across the Florida Panhandle and coastal sections of Georgia and Florida. A surface area of low pressure developed along the cold front (which had since stalled out across the western Atlantic and into the Gulf of Mexico) early on December 23 and steadily intensified. By early the next morning, the upper-level disturbance became oriented in a northwest to southeast fashion. This, coupled with the intensifying surface low, strengthened easterly winds off the Atlantic Ocean and enhanced convergence, leading to a large area of heavy snowfall along the coastline of North Carolina.[3] As the surface low progressed north or northeast, it remained south of the 32°N 75°W benchmark (about 215 mi (345 km) southeast of Cape Fear, North Carolina) that most significant Carolinas snowstorms pass near. Nonetheless, heavy snowfall continued to fall across most of eastern North Carolina, although a narrow zone of warm air around the northern half of the surface low precipitated a changeover to sleet and rain across the Outer Banks at the end of the event. As the system moved away from the United States coastline late on December 24, associated precipitation began to wind down, leaving record-breaking snowfall and unparalleled arctic air in its wake.[1]

References

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  1. ^ a b c d e Tim Armstrong (December 7, 2014). Christmas Coastal Snowstorm: December 22-24, 1989 (Report). National Weather Service Weather Forecast Office in Wilmington, North Carolina. Retrieved January 7, 2017.
  2. ^ a b 20 Years Ago: The December 1989 Arctic Outbreak across the North Country (PDF) (Report). National Weather Service Weather Forecast Office in Burlington, Vermont. Retrieved January 7, 2017.
  3. ^ Chris Collins. Christmas Snowstorm December 23, 1989 (Report). National Weather Service Weather Forecast Office in Morehead City, North Carolina. Retrieved January 7, 2017.