In Like a Lamb . . .
March 16, 2012
Spring weather has come early to the United States, according to meteorologists at the National Oceanic and Atmospheric Administration (NOAA). On March 14, 400 locations around the United States reported record highs. Even the 68 °F (20 °C) temperature at Duluth, Minnesota, which was far below the 80 °F (27 °C) reported in Miami, Houston, and Chicago, was 35 Farhrenheit degrees (19 Centigrade degrees) above average.
Spring 2012 is following the fourth-warmest U.S. winter since record keeping began in 1895. Unseasonably warm temperatures have resulted in such welcome developments as lower natural gas heating costs for consumers, as well as concerns among farmers that spring frosts may damage crops that produce buds this early.
Because of the early arrival of spring in the United States, the famous cherry blossoms that tourists flock to the nation's capital to see are expected to bloom early. (Courtesy Dean Brown from Nancy Palmer)
The winter of 2012, which meteorologists define as the period from Dec. 1, 2011, to Feb. 29, 2012, brought no major snowstorms to the United States. Snow cover in early March, as photographed by NASA’s Terra Earth observing satellite, was much spottier and less thick than the snow cover recorded for the same time in 2011.
The less extensive snow cover, according to NOAA scientists, has lowered the risk of spring flooding. For the first time in four years, no area in the United States was expected to experience major spring flooding, according to an agency report released on March 15. At this time in 2011, half the country was at above-average risk of flooding.
According to meteorologists, the warm spring weather may be the result of two climate patterns in effect in 2012. One is a La Nina, during which cooler-than-normal water temperatures in the eastern Pacific Ocean produce warmer-than-normal temperatures and drier conditions in much of the United States. A strong La Nina has been in effect throughout 2011 and is just beginning to dissipate. Another weather pattern affecting U.S. climate is the Arctic Oscillation (AO). That phenomenon, in which changes in air pressure affect the circulation of warm and cold air masses in the upper atmosphere, has been bottling up cold Arctic air in regions around the North Pole.
Will the warm weather continue? NOAA forecasters indicate that temperatures for the rest of March, April, and May will probably be about one Fahrenheit degree (0.6 Centigrade degree) above normal. Nevertheless, one or two extreme temperature fluctuations during that period remain possible.
Additional World Book articles:
