NCEI added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.
The data presented in this
drought report are preliminary. Ranks, anomalies, and percent areas
may change as more complete data are received and
National Drought Overview
*This drought statistic is 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.
|The most extensive
national drought coverage during the past 100 years (the period of
widespread reliable instrumental records) occurred in July
80 percent of the contiguous U.S. was in moderate to extreme
drought. Although the current drought and others of the 20th
century have been widespread and of lengthy duration, tree ring
records indicate that the severity of these droughts was likely
surpassed by other droughts including that of the 1570s and 1580s
over much of the western U.S. and northern Mexico.
Regional Drought Overview
|At its peak
last year, the 2004 drought affected about
two-thirds of the West (Rocky Mountains to West Coast).
Abundant rain and record snowpacks from winter storms beginning in
September 2004 brought relief to the
Southwest, with only about
19 percent of the West affected by moderate to extreme drought
by the end of January 2005.
|While the West was
experiencing wet conditions, the drought focus shifted to the
middle part of the country. Starting in the spring,
unusually dry weather settled in over the Midwest
throughout the spring,
winter, and part
across much of
Texas. Especially hard-hit were
northern Illinois and the
Arklatex region (southwestern Arkansas, southeastern Oklahoma,
northeastern Texas), both of which experienced the driest year in
the 111-year record.
streams, reservoirs, and stock ponds, depleted soil moisture
pastures and rangeland, and numerous
wildfires prompted governors and the USDA to declare drought
disasters in parts or all of several states (Arkansas, Illinois,
Iowa, Kansas, Missouri, Texas, and Wisconsin). National corn,
soybean, and wheat crop yields were below last year's records, but
still above average. By the end of the year, a band
of moderate to extreme drought stretched almost continuously
from the Texas Gulf coast to Upper Michigan.
|Parts of the Northeast
experienced short-term dryness during early
summer, with dryness returning to much of the Eastern Seaboard
and Pacific Northwest during the late
summer to early fall. Three states (Georgia, Maryland, South
Carolina) had the
driest September in the 111-year record, and six states
(Delaware, Maryland, Oregon, South Carolina, New Jersey, Virginia)
had the tenth driest, or drier,
|The year ended with a very
dry month from the Southwest across the southern Plains to the
Ohio Valley and eastern Great Lakes. Several states from the
Southwest to Lower Mississippi Delta had the
tenth driest, or drier, December, including
Arkansas with the driest December in the 111-year record.
marked a turnaround in moisture conditions for the
Southwest, where 12 months ago the weather was unusually
wet. An examination of USDA snowcourse/snotel station data in
Arizona revealed that 31 of 33 sites, or 94% of them, were snow
free at the end of the year, the
most snow-free locations in at least the past 40 years.
December capped a three-month
period of exceptionally dry weather for the
southern Plains, with
Arkansas and the
Arklatex experiencing the driest
October-December on record. Dry, windy, and warmer-than-normal
weather contributed to the outbreak of numerous
grassfires in Oklahoma, Texas, Arkansas, and New Mexico.
Pre-instrumental Drought Perspective
|Tree ring records
provide a useful paleoclimatic index that extends our historical
perspective of droughts centuries beyond the approximately 100-year
instrumental record. Several paleoclimatic studies have shown that
droughts as severe or worse, both in magnitude and duration, than
the major 20th century droughts have occurred in the U.S. during
the last thousand years. The following paleodrought reports have
been prepared by the NOAA/NCDC Paleoclimatology
Monitoring branches during 2005:
Citing This Report
NOAA National Centers for Environmental Information, State of the Climate: Drought for Annual 2005, published online January 2006, retrieved on September 2, 2015 from http://www.ncdc.noaa.gov/sotc/drought/200513.