WARMEST
APRIL ON RECORD IN U.S.
Drought Persists Across South and Southwest
May
16, 2006 � The contiguous United States experienced its warmest
April ever based on records dating back to 1895, according to scientists
at the NOAA National
Climatic Data Center in Asheville, N.C. Drier-than-average conditions
and severe drought persisted across large portions of the southern and
southwestern United States. April also was marked by a series of tornado
outbreaks during the first half of the month impacting large parts of
the Midwest and central Plains, into the Deep South. The global surface
temperature was the seventh warmest April on record. (Click
NOAA illustration for larger view of warmest April on record. Please
credit “NOAA.”)
U.S.
Temperature
The average temperature for the contiguous United States for April (based
on preliminary data) was the warmest in the 1895-2006 period of record,
breaking the previous record for the month, set in 1981. April was 4.5
degrees F (2.5 degrees C) above the 20th century (1901-2000) average.
The anomalous warmth was particularly concentrated over the south-central
United States. Texas and Oklahoma had their warmest April on record,
while New Mexico, Kansas, Arkansas, Missouri and Tennessee recorded
their second warmest. Twelve other states recorded one of their top
five warmest Aprils on record. None of the 48 contiguous states was
cooler-than average. However, temperatures across Alaska were cooler
than average during April, with a statewide temperature of 0.85 degrees
F (0.47 degrees C) below the 1971-2000 mean. The record warm temperature
led to below normal residential energy demand for the U.S., as measured
by the nation's Residential Energy Demand Temperature Index. Using this
index, NOAA scientists determined that the nation's residential energy
demand was approximately 12 percent less than what would have occurred
under average climate conditions for the month. (Click NOAA
image for larger view of April 2006 statewide temperature rankings.
Please credit “NOAA.”)
U.S.
Precipitation
Precipitation was near average for the contiguous United States, ranking
45th wettest in the 1895-2006 record. Wetter-than-normal conditions
occurred in 12 states, mostly across the western and north central United
States. California, Nevada, Idaho and Montana experienced one of their
top 10 wettest Aprils on record, continuing a pattern of wetter-than-normal
conditions that has persisted in that part of the country for much of
the past six months. Heavy rain and snow at the start of the month contributed
to flooding in coastal and valley areas of northern and central California,
with some locations accumulating more than eight inches above normal
monthly precipitation. (Click NOAA image for larger view of
April 2006 statewide precipitation rankings. Please credit “NOAA.”)
A beneficial,
late-season heavy snowfall blanketed the Black Hills of South Dakota
and surrounding areas April 18-20. Most of the affected area received
12 to 24 inches of snow. More than 60 inches fell in Lead, S.D. High
elevations in California continued to have well above normal spring
snowpack with some places more than 200 percent of the 1951-2000 average
at the end of April. Unusually warm temperatures and rapid snow melt
in Wyoming reduced early May snowpack levels there to well below average.
Ten states
were drier than normal, primarily in the southwestern and southeastern
United States. Only Colorado experienced well below normal precipitation,
recording its 11th driest April. Precipitation deficits in the Southeast
followed a record dry March for the region and led to a continuation
or worsening of conditions in the region.
At the
end of April, moderate-to-extreme drought
(as defined by a widely used measure of drought—the Palmer Drought
Index) affected 31 percent of the contiguous U.S., an increase of 5
percent from March. Drought persisted across much of the south central
and southwestern United States, stretching into the western High Plains
and Missouri Valley. Drought and abnormally dry conditions also extended
from parts of the Northeast to Florida and Gulf coastal areas, according
to the U.S. Drought Monitor. Parts of the Upper Peninsula of Michigan
and northern Wisconsin also were in moderate drought. Exceptional drought
developed during April in southeastern Arizona and southwestern New
Mexico, and persisted in southern Texas.
Four tornado
outbreaks occurred in the eastern Plains and Midwest in April. On April
2, 86 tornadoes were reported in the region bordered by Arkansas, Iowa,
Indiana and Tennessee in association with a strong cold front. Tennessee
was particularly hard hit, with 23 confirmed fatalities. An April 7
outbreak of 91 reported tornadoes occurred in the Tennessee valley,
killing nine in the suburbs of Nashville. Twenty tornadoes were reported
on April 13, mostly in eastern Iowa. One person was killed, and there
was significant damage in Iowa City. A final large outbreak of 24 reported
tornadoes hit east central Illinois on April 16 with no deaths reported.
Globe
The average global temperature anomaly for combined land and ocean surfaces
for April (based on preliminary data) was 0.88 degrees F (0.49 degrees
C) above the 20th century mean. This was the seventh warmest April since
1880 (the beginning of reliable instrumental records). The warmest April
was in 1998 with an anomaly of 1.26 degrees F (0.70 degrees C) above
the mean. Land surface temperatures were eighth warmest on record for
April with above average temperatures over the majority of North America,
Europe and Scandinavia. Cooler-than-average temperatures occurred from
central Russia to the Far East.
Heavy rain
events and associated flooding occurred throughout April in Yemen, Colombia,
Eastern Europe, northeastern Australia, Indonesia and northern Argentina.
Flooding and landslides caused significant loss of life and property
damage in many of these locations. Precipitation estimates for northwestern
Colombia from March 1 to April 16 exceeded 27 inches (700 mm). In Eastern
Europe in mid-April, the Danube River reached its highest level in 111
years. Cyclone Monica became the strongest tropical cyclone of 2006.
It reached Category 5 on the Australian scale, with 135 knots (155 mph)
sustained winds before weakening as it crossed over northeastern Australia.
The tropical cyclone season in the Australian region has been near average
with the development of 12 storms, two more than average. Although final
assessments of tropical cyclone strength are continuing, it is thought
that 25 percent of these storms reached Category 5 strength on the Australian
scale.
NOAA, an
agency of the U.S. Department of
Commerce, is dedicated to enhancing economic security and national
safety through the prediction and research of weather and climate-related
events and providing environmental stewardship of the nation's coastal
and marine resources.
Through the emerging Global Earth Observation System of Systems (GEOSS),
NOAA is working with its federal partners, 61 countries and the European
Commission to develop a global network that is as integrated as the
planet it observes, predicts and protects.
Relevant Web Sites
Climate
of 2006—April in Historical Perspective
NOAA National Climatic
Data Center
NOAA
Drought Information Center
Media
Contact:
John Leslie, NOAA
Satellite and Information Service, (301) 817-4410
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