State of the Climate
Drought
October 2007

National Oceanic and Atmospheric Administration

National Climatic Data Center

Use the form below to access monthly reports.

« September 2007
Drought Report

November 2007 »
Drought Report

Report:

Year: Month:

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 October 2007, a decrease of about 11 percent compared to last month. By contrast, about 15 percent of the contiguous U.S. fell in the severely to extremely wet categories.
About 27 percent of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of October.
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 graphic, severe to extreme drought graphic).

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).
Based on the U.S. Drought Monitor, at the end of October, moderate to exceptional drought affected about 67 percent of the Southeast, 57 percent of the West, and 35 percent of the contiguous U.S.

Detailed Drought Discussion

During October 2007, beneficial rain fell across parts of the Southeast, but the rain missed a large part of the core drought area. Meanwhile, the southern Plains to Southwest was drier than normal. Long-term drought conditions continued across much of the Southeast and West, with spotty patches of drought in other parts of the country.

Most of the stations in Alaska were drier than normal during the month. October was dry for most of the Hawaiian Islands, continuing a dry pattern that has lasted several months. The northwestern portion of Puerto Rico was drier than normal during October, but above-normal rainfall occurred over the southeastern sections which have seen persistently below-normal conditions for several months.

A subtropical high pressure system has been responsible for blocking rainfall across much of the Southeast during the spring and summer and now into the fall. Significant moisture deficits have built up over the last several months (3 months, 6 months, 9 months, 12 months), reaching record and near-record levels for some states.

About 42 percent of the western U.S. (Rockies westward) fell in the moderate to extreme drought category, and about a third fell in the severe to extreme category (as defined by the Palmer Drought Index) by the end of this month.

The persistent dryness has depleted soil moisture, ravaged pastures, and dried up streams. Soil moisture (both modeled and observed) and streamflow (both modeled and observed) were most severely affected in the three core drought areas: the Southeast, upper Great Lakes, and West.

Map showing 9-Month Standardized Precipitation Index

A more detailed drought discussion can be found below.

SOUTHEAST DROUGHT
As summarized by the Southeast Regional Climate Center, drought persisted across much of the Southeast during October, particularly in an arc stretching from western Virginia through the western Carolinas to northern Georgia and northeast Alabama. There was some relief on October 24-26 when an upper-level low pressure system to the west brought 2 to 6 inches of rain over much of the area. As a result, the area in the D4 (Exceptional Drought on the U.S. Drought Monitor) category, which had been increasing early in the month, decreased slightly. At month's end, slightly less then a third of the region was still in Exceptional Drought, although more than half was covered either by Extreme or Exceptional Drought conditions. Only the northeastern and the southern parts of the region saw an overall improvement as the month progressed. For rainfall year-to-date values, many stations were hovering around the second or third driest on record. For example, so far (as of November 7) in 2007 Atlanta has received a total of 26.11 inches of rain, the third driest year-to-date on record, behind 1931 (23.61") and 1954 (24.68"). And the official National Weather Service forecast suggests that, during the next few months, the drought conditions will at least persist, and possibly intensify, for all areas of the Southeast.

Some specifics:

Several deep wells, ponds, and springs in the Southeast have dried up.
Streams were at record or near record low levels, with some at flow levels half the previous record low.
Reservoirs that supply water to major urban centers continued to drop, with some areas (such as Atlanta, GA and several communities in NC) having as little as three months of water supply remaining. Many cities in the region have instituted mandatory water restrictions. In North Carolina, Gov. Easley has said, "If we do not get significant rain, some areas face the once unthinkable possibility of water rationing and potentially running out of water entirely." Low water levels in Lake Lanier, which services Atlanta, prompted a meeting between the governors of Georgia, Alabama, and Florida, and other interests, to modify water management practices for the water in Lake Lanier.

NORTHEAST DROUGHT
Governor Rell issued a drought advisory for the state of Connecticut on October 5. The officials in several Connecticut towns enacted emergency rules encouraging water conservation.

Delaware's Governor Minner requested drought disaster relief from the USDA in September and, in mid-October, issued a statewide drought watch urging residents to voluntarily conserve water.

OTHER AREAS
According to a University of Nebraska report, levels in Lake Mead (in the Southwest U.S.) continued to fall. The October 2007 Lake Mead level was at 1111.1 feet, which is 15 feet lower than this time last year, the lowest October level since 1964, and the fourth lowest October level in 70 years of record.

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