NOAA03-052 CONTACT: John Leslie
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May 15, 2003
NOAA REPORTS DROUGHT CONDITIONS IMPROVING IN PARTS OF U.S.
WITH WETTER-THAN-AVERAGE FEBRUARY-APRIL
Above-average precipitation throughout much of the United States during the
past three months led to improving drought conditions in many areas, according to
scientists at the National Oceanic and Atmospheric Administration's (NOAA) National
Climatic Data Center (NCDC) in Asheville, N.C. NOAA is part of the Commerce
Department.
Twenty-four percent of the contiguous United States was in moderate-to-extreme
drought in April, down from 37 percent in January and 50 percent during the summer of
2002, based on a widely used measure of drought severity, the Palmer Drought Index.
NCDC researchers said precipitation averaged across the contiguous United
States was 0.5 inch (12.7 mm) above the 1895-2003 long-term mean for the February
through April three-month period, based on preliminary data. Twenty seven states were
significantly wetter than average and 11 states were significantly drier than average.
Wetter-than-average conditions were prevalent in the Mid-Atlantic, Southeast and in
most states of the western United States. Near-average to drier-than-average
conditions stretched from Maine to the Upper Midwest and southwest to Texas.
The precipitation helped alleviate extremely dry conditions in many areas, but the
rain and snowfall were not sufficient to end the drought in many parts of the West,
where severe drought has occurred for much of the past three to five years. In
Colorado, which had its driest year on record in 2002, a single snow storm in March
brought a near-record snowfall of 32 inches to Denver Stapleton Airport and totals
exceeding 80 inches in higher-elevation locations to the west.
Snow pack, an important source of water for western states, was near or above
average at the end of April in much of the front range of the Rocky Mountains from
Montana to Colorado and the Sierra Mountains, but snow pack remained below average
in large parts of the West. Reservoir storage was also below average in every western
state except Washington at the end of April, and river flows remained below average in
a large part of the western two-thirds of the nation.
In Montana, where conditions in parts of the state during the summer of 2002
were similar to those experienced during the Dust Bowl years of the 1930's, above
average precipitation during the past several months led to a marked improvement in
drought conditions. However, according to the U.S. Drought Monitor, severe drought
continued to affect a large part of the state at the end of April.
Based on the Palmer Drought Index, the percent of the West in moderate to
extreme drought decreased from 81 percent in November 2002 to 44 percent in April.
The most widespread drought in the instrumental record occurred in July of 1934, when
97 percent of the West and 80 percent of the contiguous United States were in
moderate to extreme drought. The percent of the contiguous United States in moderate
to extreme drought fell to 24 percent in April.
Temperatures during the February-April 2003 period were near average to
slightly warmer than average across most of the country. The Northeast was the only
region with significantly cooler-than-average temperatures. For the contiguous United
States as a whole the February-April temperature was 43.3 F (6.3 C), slightly warmer
than the 1895-2003 mean. In Alaska the three-month period was 6.0 F (3.3 C) warmer
than the 1971-2000 average. During the past 25 years, temperatures in Alaska have
averaged 3.2 F (1.8 C) warmer than during the preceding 50 years.
El Nino
The moderate El Nino episode that began in 2002 weakened during the
February-April period, while the average global temperature for combined land and
ocean surfaces (based on preliminary data) during April was 0.9 F (0.5 C) above the
1880-2002 long-term mean. This was the fourth warmest April but 0.4 F (0.2 C) cooler
than the record warm April which occurred near the end of the 1997-98 El Ni¤o
episode. The land-surface temperature average was the seventh warmest on record for
April (1.4 F above average), and the global ocean-surface temperature was 0.7 F above
average, approximately 0.2 F cooler than April 1998. The year-to-date global average
for combined land and ocean surfaces was the third warmest on record.
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http://www.ncdc.noaa.gov/oa/climate/research/2003/apr/apr03.html.
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