While Global Temperatures Remain High
December 18, 2003
The average temperature for the contiguous United States in 2003 is expected to be near 53.6° F (12.0° C). Much of 2003 was marked by near-average to cooler-than-average temperatures in the East and much higher-than-average temperatures in the western half of the nation. From January to November, 10 western states were much warmer than average, including New Mexico, which had its warmest January-November on record. Eight states east of the Mississippi River were significantly cooler than average, and every other state except Florida was near average. Temperatures in Alaska were above the 1971-2000 average in all four seasons, and 2003 is estimated to be one of the five warmest years since the beginning of Alaska statewide records in 1918.
U.S. Precipitation and Drought
The year was also marked by a sharp contrast in precipitation across the country. While drier-than-average conditions persisted throughout much of the West, all but four states east of the Mississippi were significantly wetter than average for the January-November period. Three mid-Atlantic states (North Carolina, Virginia and Maryland) had their wettest January-November on record, and 12 other states were much wetter than average. Precipitation in Virginia had already exceeded the record annual total for the state by the end of November.
Conversely, 17 states along and west of the Mississippi River were significantly drier than average. The combination of below-average precipitation and warmer-than-average temperatures contributed to persistent or worsening drought conditions.
Near year's end, moderate to extreme drought covered approximately 70 percent of 11 western states, a region where drought has persisted for the past three to five years in many locations. A major late winter storm that brought a near-record snowfall of 32 inches (81 cm) to Denver and totals exceeding 80 inches (203 cm) in higher elevation locations of the Front Range helped alleviate drought in parts of Colorado, but seasonal snowfall totals were well below average in much of the remainder of the West.
The persistent lack of adequate rain and snowfall left reservoirs throughout much of the West below average near the end of 2003, and the continuation of even moderate drought conditions has had an impact on water supplies. Lake Mead, an important reservoir in the Colorado River system, was approximately two-thirds of its total capacity near the beginning of summer, and summertime levels have been dropping since 1999 (NASA Report: http://earthobservatory.nasa.gov/Study/LakeMead/).
However, lower levels of this reservoir and others in the West, have been reported during periods of persistent drought in the 1950s and 1960s. Tree-ring records from the Upper Colorado River basin indicate that droughts like those of the 1950s and 1960s are not uncommon in that area, and droughts more persistent and intense than those in the instrumental record (20th, 21st centuries) have occurred in the past 700 years.
The dry conditions also contributed to an active wildfire season in the western states. However, the number of acres burned in the United States through the end of November was 3.8 million acres, slightly less than the eight-year annual average and much less than the nearly 7 million acres burned in 2002, according to the National Interagency Fire Center.
At the end of November, 37 percent of the contiguous United States was in moderate-to-extreme drought in an area that stretched from Wisconsin to Texas and the Pacific coast states. The most extensive national drought coverage during the past 100 years (the period of instrumental record) occurred in July 1934, when 80 percent of the contiguous United States was in moderate-to-extreme drought.
The drought statistics are based on the Palmer Drought Index, a widely used measure of drought. The Palmer Drought Index uses numerical values derived from weather and climate data to classify moisture conditions throughout the contiguous United States and includes drought categories on a scale from mild to moderate, severe and extreme.
Atlantic Hurricane Season
Sixteen named storms formed in the Atlantic basin during 2003, including Hurricane Isabel, which was the first hurricane to make landfall along the East Coast since 1999. Tropical Storms Odette and Peter formed after the traditional end of the hurricane season. Odette was the first tropical storm to have developed in the Caribbean during December. Of the16 named storms, seven became hurricanes and three were classified as major hurricanes (Category 3 or higher on the Saffir - Simpson hurricane scale). The annual average is five to six hurricanes and two to three major hurricanes.
According to NOAA's National Hurricane Center, several factors contributed to the very active season including the absence of El Niño conditions in the Pacific and the persistence of conditions associated with the continuation of a multi-decadal period of enhanced activity that began in 1995. With the exception of 2002 and 1997, years that were both affected by El Niño, at least three major hurricanes have developed in every season since 1995. However, no significant long-term trend in hurricane strength or frequency has been observed in the Atlantic Basin.
Data collected from weather and climate stations, satellites, ships, buoys and floats indicate that the 2003 average global temperature will likely be the third-warmest on record, slightly lower than 2002 and cooler than the record warm year of 1998. The 10 warmest years have all occurred since 1991. The year began with a moderate El Niño in the equatorial Pacific, but the episode ended by April, and near neutral conditions persisted across the equatorial Pacific the remainder of the year.
During the past century, global surface temperatures have increased at a rate near 1.0° F/Century (0.6° C/Century), but the trend has been three times larger since 1976, with some of the largest temperature increases occurring in the high latitudes. In 2003, warmer temperatures and shifts in atmospheric circulation patterns contributed to a second straight year of extremely low Arctic sea ice extent in September, according to the National Snow and Ice Data Center. However, Northern Hemisphere sea ice extent was more than that observed in September 2002.
Data collected by NOAA's polar orbiting satellites and analyzed for NOAA by the University of Alabama in Huntsville and Remote Sensing Systems in Santa Rosa, Calif., also indicate that temperatures centered in the middle troposphere at altitudes from two to six miles are on pace to make 2003 the third-warmest year for the globe. The average lower troposphere temperature (surface to about five miles) for 2003 will also likely be the third warmest since the beginning of annual satellite measurements in 1979.
Through the end of November, temperatures for the year were as much as 3° F (1.7° C) above average across large parts of Asia, Europe and the western United States. Warmer-than-average temperatures also covered much of South America, Australia, Canada and parts of Africa, while widespread areas of cooler-than-average temperatures occurred in the eastern United States, western Asia, and coastal areas of Australia.
A record summer heat wave contributed to the large year-to-date anomalies in Europe. The all-time maximum temperature record in the United Kingdom was broken on Aug. 10, when the mercury reached 100.6° F (38.1° C) at Gravesend-Broadness (Kent). France had its warmest summer on record. According to news reports, more than 14,000 people died of heat-related causes during the peak of the heat wave in late July and August.
Temperatures also soared across southern Asia in late May and June. During a 20-day heat wave, maximum temperatures reached as high as 113-122° F (45-50° C), and more than 1,500 deaths occurred in India, according to news reports.
Conversely, extremely cold winter temperatures occurred across Asia in January. Temperatures in northwestern Russia were as low as -50° F (-45° C), and thousands of deaths were attributed to extremely cold conditions in India and Bangladesh during the month, according to published reports. Moscow received snowfall in June for the first time since 1963. In the Peruvian highlands, temperatures dropped below -5° F (-20° C) during the Southern Hemisphere winter month of July, which led to the reported deaths of more than 200 people.
In Argentina, Santa Fe was reportedly hit by its worst flooding in centuries due to several days of heavy rainfall in April and May, which caused major rivers to overflow their banks. Heavy rains associated with Typhoon Maemi in September triggered landslides and flooding that were responsible for more than 130 deaths and the evacuation of more than 25,000 people from their homes in South Korea.
Normal-to-above-normal rainfall in the Sahel led to ideal growing conditions in much of this region of Africa. Rainfall in Zimbabwe and Mozambique brought some drought relief during the austral spring (September-November), but drought persisted in parts of those countries as well as South Africa and Botswana near years-end.
NOAA's Satellites and Information Service is the nation's primary source of space-based and surface-based meteorological and climate data. NOAA Satellites and Information Service operates the nation's environmental satellites, which are used for weather forecasting, climate monitoring and other environmental applications such as fire detection, ozone monitoring and sea surface temperature measurements.
NOAA Satellites and Information Service also operates three data centers, which house global data bases in climatology, oceanography, solid earth geophysics, marine geology and geophysics, solar-terrestrial physics, and paleoclimatology.
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