July 2010 Wildfires Report

Large Fire Maps:
[ July 2  |  July 15  |  July 30 ]

During July, the number of acres burned by wildfires and the number of individual wildfires were below normal, attributable in part to the much–above–average precipitation that fell across the U.S. during the month. Temperatures averaged for the entire U.S were also above average. The eastern half of the country was dominated by above–normal temperatures, while the West was more of a mixed picture. Arizona temperatures were much warmer than average, while Texas, Montana, and Idaho had below–average temperatures. Precipitation during the month predominatly fell across the center third of the country, with the western and eastern thirds generally experiencing below–average precipitation amounts during July. See the national temperature and precipitation State of the Climate report for additional information. Large fire activity was mostly confined to states with near– to below–average precipitation. At the beginning of July, large wildfires were occuring mostly in the western United States, with 17 fires active — six in Alaska; three in Colorado; two in New Mexico, Arizona, and Idaho; and one in both Nevada and Florida. By mid–July the number of large fires decreased to 11 — three in Alaska; two in California and Washington; and one in Montana, Idaho, Arizona, and New Mexico. A dry finish to July created favorable conditions for large fires. By July 30^th, 22 large fires were burning across the United States with seven fires in California; three in Nevada; two in Montana, Alaska, and Florida; and one each in Washington, Oregon, Idaho, Colorado, and New Jersey.

A wildfire in Idaho spread rapidly from being a small fire to covering 170 square miles (440 square km) in less than 24 hours. The fire began on the lands of the Idaho National Laboratory near Idaho Falls on July 13^th. Strong winds and dry conditions fueled the rapid fire growth. The fire was a particular danger due to the nuclear fuel research which occurs at the Idaho National Laboratory, but fortunately no significant damages were sustained to the facility. The fire was contained on July 15^th, but not before charring 109,305 acres (44,234 hectares).

Three large fires the last week of July prompted Governor Schwarzenegger to declare a state emergency in California, allowing the allocation of state resources to fight the fires. The Bull fire and West fire occurred in Kern County. Combined both fires burned 17,700 acres (6,961 hectares) and destroyed nearly 40 homes and numerous other structures. The Crown fire burned 14,000 acres (5,666 hectares) in Los Angeles County. 2,300 evacuations were ordered as all three fires spread rapidly. By the end of the month the fires were mostly contained, as weather conditions became more favorable for firefighters.

According to statistics from the National Interagency Fire Center (NIFC), at the end of July, the number of nationwide fires year–to–date was 36,826 which burned 1,978,537 acres (800,686 hectares) with an average of 54 acres (22 hectares) per fire. Between July 1^st and July 29^th, approximately 491,856 acres (199,047 hectares) burned across the U.S., which is 71 percent below the 2000-2009 average and marked the second least July acreage burned since 2000. A total of 7,015 new fires were reported during the month, which is 26 percent below the 2000-2009 average and the third lowest number of new July fires reported since records began in 2000. The average number of acres burned per fire was 70 (28 hectares) during July and is 66 percent below the 2000-2009 average and the second least acres burned per fire in the 11-year period of record.

Despite the U.S. experiencing its 11^th wettest July, drought conditions changed little during the month, according to the U.S. Drought Monitor. In the West, the severe drought in western Wyoming improved one category to moderate drought, while severe and moderate drought expanded in northern Arizona. In central Alaska, beneficial rainfall ended the on-going moderate drought there, and in Hawaii there was little drought relief. In the central part of the country, an active storm pattern brought very wet conditions from Texas to the Canadian border. This alleviated the severe drought in northern Texas and shrank the drought footprint in the western Great Lakes. The moisture did not stretch far east, as the drought in the lower Mississippi River Valley experienced no improvement. In the Mid-Atlantic and Southeast, drought conditions worsened with moderate drought developing in Alabama, the Carolinas, Delaware, Pennsylvania, and New Jersey. Severe drought developed along coastal Virginia and Maryland.

According to the U.S. Forest Service (USFS) Wildland Fire Assessment System, at the beginning of July, high fire danger was confined to the interior west, with very high and extreme fire danger in the Great Basin, southern California, and northern Arizona. By the middle of July, the extreme fire danger in the Great Basin had decreased. Very high fire danger was present for most of the Rockies from the Canadian border to the Mexican border. Very high fire danger was also reported in the arrow head of Minnesota. At the end of July, the very high fire danger lessened across the eastern Rockies, but expanded across Nevada. High fire danger was also present across southern Georgia.

According to the USFS Wildland Fire Assessment System, on July 1^st the driest fuels of all sizes were present across the West. Small and medium sized fuels (10-hour and 100-hour fuel moistures) were present across the central and northern plains stretching into the Mid-Atlantic. Dry large fuels (1,000-hour fuel moistures) were confined to the Southwest. On July 15^th, small fuels moistened across the central Plains where precipitation had fallen. The dry fuels across the Mid-Atlantic stretched northward into New England and southward across the Southeast and the Gulf Coast. Very dry small fuels were present along and west of the Rocky Mountains. The low 100-hour fuel moistures across the eastern U.S. moistened significantly, limiting the dry 100-hour and 1,000-hour fuel moistures to the interior West. At the end of July the dry small fuels persisted across the Eastern U.S., while the 10-hour fuel moistures increased significantly across the Northern Plains and Western Great Lakes where precipitation was widespread. Small fuel dryness increased across the Southern Plains and Gulf Coast. Dry larger fuels (100-hour and 1,000-hour fuel moistures) continued to be present only in the interior West. In Alaska, small fuels (10-hour fueld moistures) became progressively drier through the month across the northern half of the state, while the 100-hour and 1,000-hour fuel moistures remained high.

According to the USFS Wildland Fire Assessment System, at the beginning of the month, high Keetch–Byram Drought Index (KBDI) values were widespread across the southern half of the United States. High KBDI values stretched from Long Island in New York, along the mid-Atlantic coast to the Southeast and the Gulf Coast, into the southern Plains, Southern Rockies, and the Great Basin. The highest KBDI values were present across Northern Louisiana, which has been suffering from drought for the past several months. By mid-July, the high KBDI values spread further along the Gulf Coast, Southeast, and mid-Atlantic where conditions were continued to be dry. At the end of July, the high KBDI values persisted in the East, and increased across the western states of Arizona, Nevada, and California. The highest KBDI values continued to be located in the Lower Mississippi River Valley, where little precipitation fell and hot temperatures persisted throughout July.

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Additional Links

• NOAA Fire Products
• U.S. Drought Monitor
• National Interagency Fire Center
• U.S. Forest Service Active Fire Mapping Program
• Wildland Fire Assessment System
• Alaska Interagency Coordination Center
• Canadian Interagency Forest Fire Center