State of the Climate
Drought
April 2007

National Oceanic and Atmospheric Administration

National Climatic Data Center

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Drought Report

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Contents Of This Report:

National Drought Overview
Detailed Drought Discussion
State/Regional/National Moisture Status
Pre-Instrumental Perspective

National Overview

Based on the Palmer Drought Index, severe to extreme drought affected about 18 percent of the contiguous United States as of the end of April 2007, about the same as last month. By contrast, about 11 percent of the contiguous U.S. fell in the severely to extremely wet categories.
About 30 percent of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of April .
On a broad scale, the previous two decades (1980s and 1990s) were characterized by unusual wetness with short periods of extensive droughts, whereas the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness (moderate to extreme drought, severe to extreme drought).

A file containing the national monthly percent area severely dry and wet from 1900 to present is available for the severe to extreme and moderate to extreme categories.
Historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page in files having names that start with "drd964x" and ending with "txt" (without the quotes).

Detailed Drought Discussion

At the end of April extreme drought was concentrated in the Southwest, the western High Plains, northern Minnesota, and the Southeast. Drought and abnormal dryness covered a broad swath from the Southwest through the northwestern Plains into the upper Midwest, as well as another area in most of the Southeast (May 1 Drought Monitor). Conditions in southern California and southwestern Arizona continued to deteriorate.

Storm systems throughout the month brought much needed precipitation to the Plains and upper Midwest and eliminated the drought conditions that had persisted for many months.

In the Southwest, Southeast and upper Midwest, soil moisture was low. At the end of the month vegetation was stressed over a large part of the country. Streamflow was low in a wide area of the Southeast.

Map showing Standardized Precipitation Index

Fires consumed over 50,000 acres in the Everglades in Florida in April. Low water levels in southern Florida delayed construction activities, caused increased silt in the intake of water supply systems, affected sales of landscape and horticulture materials, and led to more severe water usage restrictions. Alligators are being seen more frequently as they move in search of wetter habitat.

In central California water deliveries are being postponed, and farmers were affected by poor pastures and water shortages. Governor Arnold Schwarzenegger warned the state to plan for drought because the winter was extraordinarily dry. He also urged residents to conserve water.

Twenty-one counties in southeastern Georgia are in a state of emergency due to extreme fire danger from drought. A wildfire in the southeast part of the state was the largest in the history of Georgia.

Large ships on Lake Superior carried lighter loads to avoid striking the bottom of the lake. Recreational boats and sailboats had difficulty on Lake Superior because of low water levels. The water became so shallow that rowers in the Duluth, Minnesota Rowing Club could touch the bottom with their oars.

Impacts in drought-stricken areas have been collected and summarized by county at the National Drought Mitigation Center's Drought Impact Reporter.

State/Regional/National Moisture Status

A detailed review of drought and moisture conditions is available for all contiguous U.S. states, the nine standard regions, and the nation (contiguous U.S.):

STATES:

Alabama	Arizona	Arkansas	California	Colorado	Connecticut
Delaware	Florida	Georgia	Idaho	Illinois	Indiana
Iowa	Kansas	Kentucky	Louisiana	Maine	Maryland
Massachusetts	Michigan	Minnesota	Mississippi	Missouri	Montana
Nebraska	Nevada	New Hampshire	New Jersey	New Mexico	New York
North Carolina	North Dakota	Ohio	Oklahoma	Oregon	Pennsylvania
Rhode Island	South Carolina	South Dakota	Tennessee	Texas	Utah
Vermont	Virginia	Washington	West Virginia	Wisconsin	Wyoming

REGIONS:

Northeast Region	East North Central Region	Central Region
Southeast Region	West North Central Region	South Region
Southwest Region	Northwest Region	West Region