December 2001 Drought Report

• severe drought affected about 15 percent of the contiguous United States as of the end of December 2001;
• the coverage of the current drought peaked in August 2000 at about 36% of the contiguous U.S., which was as extensive as the major droughts of the last 40 years, but not as large as the "dust bowl" droughts of the 1930's and 1950's;
• the total drought area decreased to about 10 percent by November 2000, but has shown a general increasing trend for much of the period since then, with a slight drop recently (see graph below left);
• on a broad scale, the last two decades were characterized by unusual wetness with short periods of extensive droughts, whereas the 1930's and 1950's were characterized by prolonged periods of extensive droughts with little wetness (see graph below right);
• although different parts of the U.S. have experienced unusually wet conditions during the last 27 months, there continues to be little change in the overall national wetness picture;
• the percentage of the nation severely wet has held steady at about three to eleven percent during this period (see graph below left);
• a file containing the national monthly percent area severely dry and wet from 1900 to present is available;
• 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.

• 53rd driest (out of 107 years) for December 2001,
• 50th wettest for October - December 2001,
• 52nd driest for July - December 2001,
• 39th driest for January - December 2001.

• the Palmer Indices and Standardized Precipitation Index,
• the runoff and soil moisture conditions as calculated by the National Weather Service,
• the percent of normal precipitation map for December,
  
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• the percent of average precipitation map for the hydrologic year thus far (October 1, 2001 - January 2, 2002), and the percent of average basin snow water content map for early January, for the SNOTEL stations in the western mountains provided by the USDA Water and Climate Center,
• maps showing the departure from normal of the number of days with precipitation for December and the longest consecutive number of days with no precipitation for December,

Western U.S. Drought

A moist Pacific flow continued to bring wet winter storms to a large part of the western U.S. during December, ending short-term meteorological drought over much of the Pacific Northwest and West regions. The Pacific Northwest had the 18th wettest October-December on record during 2001, bringing well above normal water content to the mountain snowpack. However, long-term drought remained, with many reservoirs still well below normal in the region and 2001 closing as the 27th driest year on record (see graph to right below). Highlights:

• Declared drought emergencies continued in three western states (Washington, Oregon, and Idaho).
• Conditions improved in Idaho with above-normal 3-month precipitation, mountain snowpack, and modeled soil moisture. But the drought is far from over, as reservoir levels are still low with combined storage for Idaho's 21 reservoirs and lakes at third lowest since 1958. The Salmon Falls Reservoir (south of Twin Falls in central Idaho) level is the lowest since December 1962.
• December precipitation brought short-term relief to western Texas, however severe long-term moisture deficits persisted.

• Maine had the driest year in 2001 and also the driest rank for several seasons (see table below).
• The persistent lack of precipitation resulted in a rapid increase in drought severity, giving the state the worst Palmer Drought Index on record by the end of the year.
• The drought in Maine has resulted in record low well levels and streamflows at many places with uncounted wells going dry, and Governor King urgently requested citizens to conserve water. By mid - December, some public water utilities had imposed conservation measures, and several were asking for voluntary action by consumers.

• Low streamflows and lack of precipitation have caused many South Carolina lake levels to continuously drop.
• Ground water levels have also significantly fallen. Since the drought began in 1998, the annual mean water level in a shallow sand monitoring well in Aiken County has dropped approximately 2 feet (0.61 meter).
• According to the S.C. Forestry Commission, the drought contributed to the second worst southern pine beetle outbreak since records began in the early 1960s, with timber losses due to the beetles estimated at $76 million during 2001.
• The Forestry Commission also noted that 2001 had the worst fall fire season since 1991, with 2,308 fires burning 12,565 acres (5085 hectares) from September through December. This is double the average number of fires and four times the number of acres normally burned during the four-month fall season.

For additional information on the 2001 wildfire season please see the National Interagency Fire Center web site or the U.S. Forest Service Fire and Aviation web site.

NCDC's Drought Recovery Page shows the precipitation required to end or ameliorate droughts and the probability of receiving the required precipitation.

Additional climate monitoring graphics can be found at the Climate Prediction Center's monitoring pages:

• Weekly, Monthly, 3-Month, 12-Month Monitoring
• El Nino, Drought, Snow Cover, and Degree Day Monitoring
• Weekly Drought Monitoring
• Soil Moisture Monitoring