Fluctuations in us freezing rain days

Freezing rain occurrences during a 50-year period, 1949/1950-1998/1999, derived from carefully examined records of 161 first-order stations distributed across the United States, were assessed for temporal fluctuations and trends. Classification of station fluctuations based on five 10-year periods revealed five unique distribution types in areas east of the Rockies. One of these five distributions, for stations located in the western Great Plains, experienced its greatest 10-year value at the end of the 50-year period. The other four regional distributions experienced their highest 10-year value in either of the first two 10-year periods. Nationally, the 10-year period when the greatest number of stations experienced their maximum value was 1949/1950-1958/1959, while the period when the greatest number of stations experienced their minimum value fell near the end of the 50-year record (1979/1980-1988/1989). The 50-year linear trends defined one region, the western Great Plains, with increasing values, while three areas of decreasing trend were identified; the Great Lakes, the eastern Ohio River valley, and southern New England. These analyses also indicate the need to examine and consider such time-space changes in the frequency of climate variables at various spatial scales when assessing weather risks and developing climate change scenarios. [PUBLICATION ABSTRACT]