Cold Waves: Introduction
Winters across Kentucky are typically mild, but not all winters are typical. Occasionally, cold weather persists for an extended period. The average temperature for Kentucky over the month of January in 1977 was 18.4°F, compared to an average of 31.8°F for the period 1901-2000. In other cases, cold waves last for only a few days. After recording Kentucky's record low temperature of -37°F on January 19, 1994, Shelbyville saw a return of seasonable weather within a week. Weather patterns affecting Kentucky during winter are strongly influenced by the path of the jet stream across North America. The jet stream separates cold air pushing southward from the polar region and warm air flowing northward from the tropical region. Upper level winds of the jet stream average about 75 miles per hour, but wind speeds of 300 miles per hour are possible. Winds strengthen during the winter months when the position of the jet stream migrates southward. While the jet stream flows generally from west to east, its path meanders. A common winter pattern shows an upper-air ridge in western North America, as the jet stream drives northward, and a trough in the eastern region, as it dips farther south. When the jet stream dips farther south than normal, it can bring unusually cold weather to Kentucky. Residents living in cold winter climates develop an awareness of the potential hazards of frigid weather. Communities and activities are often planned in ways to minimize risks and impacts. In milder climates, the infrequent insurgence of frigid conditions can have a significant impact on life and property, simply because communities and individuals are less prepared to deal with extreme conditions. Mitigation efforts can reduce the impacts of cold waves when they hit.
|