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2000 IN REVIEW: THE YEAR BEGAN WITH RECORD WARMTH IN THE U.S. AND ENDS WITH COLDER THAN NORMAL TEMPERATURES ACROSS MUCH OF THE COUNTRY Annual U.S. and Global Temperatures Remain Well above Average
After beginning with record winter warmth, the year 2000 is ending with colder than normal temperatures across much of the nation. Although the final temperature for the year will depend on conditions during the remaining two weeks of December, the average annual U.S. temperature in 2000 is projected to be between 54.1° and 54.2°F, the seventh to twelfth warmest year on record in 106 years. This is well above the long-term (1895-1999) average of 52.8°F. Although colder than normal temperatures have affected much of the U.S. recently, the trend to warmer temperatures which began more than a century ago continues. U.S. temperatures have risen at a rate of 0.9°F/Century over the past 100 years. Within the past 25 years, U.S. temperatures increased at a rate of 1.6°F/25 years. Heat waves and drought plagued much of the southern and western U.S. in 2000, while the Midwest and northeastern U.S. experienced prolonged periods of cooler and wetter than normal conditions. July 2000 was the coolest such month on record in Pennsylvania and West Virginia, and the second coolest in New York. Precipitation was above average in fifteen states throughout the Northeast and Midwest during the summer months (June-August). The relatively cool and wet summer conditions in the Northeast and Midwest would have been welcome in the South and West, where months of below-normal precipitation and above-normal temperatures led to severe drought and widespread wildfires. States in the Deep South endured a third straight summer of below-normal precipitation. The driest May-October on record occurred in the Deep South states (Fla., Ga., Ala., Miss., La.) leading to drought conditions as severe as any observed during the 20th century. Estimated drought-related damages throughout the South and Southern Plains are estimated in the billions. The driest July-September on record occurred in the Southern region (Texas, Okla., Kan., Ariz., La., and Miss.) before torrential rains brought flooding to many cities and made November the wettest November on record in this region which experienced extreme drought only months earlier. By August 2000, 36 percent of the nation was in severe to extreme drought, although precipitation in recent months has significantly reduced the severity of drought in many areas. The widespread drought contributed to one of the worst U.S. wildfire seasons in 50 years. More than 7 million acres of forests and grasslands were consumed by fire in 2000 with the greatest losses in western states, particularly Idaho and Montana, and estimated losses nationwide of more than $1 billion. There were fewer tornadoes in 2000 than average, while Atlantic hurricane activity was above average for the third consecutive year. Sixteen very strong to violent tornadoes (winds in excess of 158 mph) occurred between March and August 2000 in the U.S. This was much less than the 1950-1999 average of 38. Throughout the past 50 years, little trend in very strong to violent tornado activity has been observed. There were 14 named tropical storms in 2000, eight of which became hurricanes with three reaching major hurricane strength. On average, nine named storms form with seven growing to hurricane strength and two developing into major hurricanes. A tendency for greater hurricane activity has occurred over the past six years after more than two decades of generally below-average activity. Five or more major hurricanes (winds in excess of 111 mph) occurred in 1995, 1996 and 1998. Prior to 1995, five or more major Atlantic hurricanes had not occurred in one season since 1964. Data collected by NOAA's TIROS-N polar-orbiting satellites and analyzed by NASA and the Global Hydrology and Climate Center at the University of Alabama in Huntsville also indicate that temperatures in the lower half of the atmosphere (lowest 8 km) were much warmer than average over the U.S. Based on eleven months of data, satellite measurements over the U.S. indicate that 2000 ranks as the fourth warmest since records began in 1979. For the Globe: Average global surface temperatures were also much warmer than normal in 2000. The global temperature is expected to be 0.7°F above the 1880-1999 long-term average, similar to temperatures recorded in 1999. The only years warmer were 1998, 1997, 1995, and 1990. The ten warmest years on record have all occurred since 1983. During the past century, global temperatures have increased at a rate near 1.1°F/Century, but this trend has dramatically increased to a rate greater than 3.0°F/Century during the past 25 years. A strong La Niña at the beginning of 2000 weakened during July and August, but was still evident at year's end. Cooler than normal temperatures throughout the eastern equatorial Pacific held down temperatures in the tropics. But temperatures in the non-tropical Northern Hemisphere continued to average near record levels. Temperatures north of 20°N were the second warmest on record during the December 1999 – November 2000 period. Annual anomalies in excess of 2°F were widespread across Canada, Scandinavia, and much of Eastern Europe and the Balkans. Global precipitation was also above-average in 2000. It is estimated that 2000 will end as one of the ten wettest years on record. Precipitation in the Tropics was heavily influenced by La Niña throughout much of the year, with above average precipitation in Indonesia and the western tropical Pacific, while drier than normal conditions were common in the central tropical Pacific. La Niña also contributed to above normal precipitation in northeast South America and southern Africa and enhanced monsoonal precipitation in southern Asia. Below normal precipitation across equatorial areas of east Africa and the Gulf coast of the U.S. is also attributable to La Niña conditions. Relevant Web Sites |
