Winter 1985 cold wave  The winter 1985 cold wave was a meteorological event, the result of the shifting of the polar vortex farther south than is normally seen. Blocked from its normal movement, polar air from the north pushed into nearly every section of the central and eastern half of the United States and Canada, shattering record lows in a number of areas. The event was preceded by unusually warm weather in the eastern U.S. in December 1984, suggesting that there was a build-up of cold air that was suddenly released from the Arctic, a meteorological event known as a mobile polar high, a weather process identified by Professor Marcel Leroux. From Sunday, January 20, to Tuesday, January 22, 1985, the polar vortex, coupled with a large ridge of high pressure, moved polar air into the United States as far south as Arizona, Texas, and northern Florida. Unlike most cold-air systems, a pattern of self-modification did not immediately occur; i.e., seasonable temperatures were absent for a number of days, a rarity in forecasting. The Arctic air mass started moving into the United States on the evening of January 19 and the morning of January 20. In Chicago, a record low of , combined with winds to produce a wind chill of . Louis saw a low of , and Pittsburgh had a low of , the coldest morning since 1899. In Cincinnati, the morning temperature of tied for the fourth-lowest minimum temperature in the city's history, outdone by a cold mass the year before and a blizzard in 1977. Cleveland fell to , which was at the time a record. Memphis recorded a low of , setting a record low for that day. The coldest temperature in the contiguous states on January 21 was , in the unlikely locations of Akron, Ohio, and Knoxville, Tennessee. As the cold air mass moved southeastward, it modified only slightly, resulting in frigid air for most of the middle and upper Eastern Seaboard starting on the morning of January 21. New York City's Central Park recorded a low of , breaking that date's record. Washington National Airport set a record of for the morning of January 21 and a record low for the prior date of . Farther south, Roanoke, Virginia, set a record low of , and the campus of the University of Tennessee at Knoxville, Tennessee, recorded a record low of . Tennessee's state capital, Nashville, dropped to , while all-time records were set well into interior sections of the deep South, such as in Charlotte; in Macon, Georgia; and in Jacksonville, Florida.