April 2010 Wildfires Report

Large Fire Maps:
[ April 9  |  April 20    |  April 30   ]

April brought an increase in the number of fires and acreage burned during the month, with dry conditions widespread across the eastern half of the country and parts of the Southwest. Above normal precipitation was present for much of the West Coast, southern Florida, and western Texas where large fires did not occur for the month. Below average temperatures for the West helped limit the spread of wildfires. See the national temperature and precipitation state of the climate report for additional information. At the end of March, fires were present in southern Plains. By the second week of April 95 large fires were active across the Ohio and Tennessee River Valleys, the Southeast, southern Plains, Northeast, southern Florida, and northern Minnesota. The fires were associated with above–normal temperatures and below–normal precipitation for those regions. By April 20^th, wildfire activity calmed down significantly with only nine large fires active in the Carolinas, Oklahoma, Mississippi, and Minnesota. Cool and wet conditions the last week of April decreased the number of large fires to two, one in Montana and one in Minnesota.

According to statistics from the National Interagency Fire Center (NIFC), by the end of April, the number of nationwide fires to–date was 20,625 which burned approximately 329,227 acres (133,233 hectares), with an average of 16.0 (6.5 hectares) acres per fire. Between March 26^th and April 30^th, approximately 188,610 acres (76,328 hectares) burned across the United States, which is 126,924 acres (51,364 hectares) below the 2000–2009 average of 315,534 acres (127,692 hectares). A total of 12,090 new wildfires were reported for the month, which is 2,077 fires above the 2000–2009 average of 10,013. This ranks April 2010 as the second highest month in terms of number of fires since 2000. The average acreage burned per fire was 15.6 acres (6.3 hectares) per fire, which is 16.3 acres (6.6 hectares) below the 2000–2009 average of 31.9 acres (12.9 hectares). This ranks April 2010 as the second lowest acres burned per fire since 2000. The location of the fires—in the eastern parts of the country versus the western regions—played a role in this statistic. Fires east of the Mississippi River tend to be smaller than fires further west.

According to the U.S. Drought Monitor, during April, drought conditions worsened for the Great Lakes, Ohio River Valley, and portions of the Southeast. Severe drought in northern Wisconsin expanded into the arrowhead of Minnesota and the Upper Peninsula of Michigan. Moderate drought conditions were declared in portions of New York, Pennsylvania, Kentucky, and Louisiana. The eastern half of the country had dry and warm conditions during the month which contributed to the expansion of the drought. Drought remained generally unchanged for most of the West, where temperatures were near– to below–normal with above–normal precipitation for the month. The additional precipitation was not enough to alleviate the on–going drought there. Abnormally dry conditions remained across a large portion of central Alaska, while the extreme–to–exceptional drought continued for the leeward Hawaiian Islands.

According to the U.S. Forest Service (USFS Wildland Fire Assessment System, on April 1^st, very high fire danger was present for the Carolinas, the Ohio River Valley, eastern Montana, most of the Mississippi River basin, and the western Great Lakes. Extreme fire danger was present for western Texas and Oklahoma. By mid–month, rain for the Southern Plains eliminated the extreme fire danger in Texas and Oklahoma, while conditions worsened in most of the Southwest, Great Basin, and parts of the Northeast. By month’s end, most of the fire danger in the middle of the country was non-existent, while high to very high fire danger was present in parts of the Southwest, the Carolinas, the Ohio River Valley, Great Lakes, and interior Northeast.

According to the USFS Wildland Fire Assessment System, at the beginning of the month, small fuel moistures (10–hour and 100–hour) were low for the majority of the country, with the exception of the West Coast, Northeast, and central Rockies. Extremely low small fuel moistures were present for the Southwest including parts of Texas, New Mexico, and Arizona. Small fuel moistures were also low for a significant portion of central Alaska. Large fuel moistures (1000–hour) for the beginning of April were low for most of the country, with the driest large fuels in Texas, New Mexico, Arizona, and Nevada. By mid–month, small fuels moistened across central Texas, and dried for the Northeast and the central Rockies. At the end of April, small fuels were dry for the majority of the country except for parts of the Northern Rockies, the Pacific Northwest coast, and California’s Central Valley. The driest small fuels were in the Southwest. Large fuel moistures changed little during the month, with conditions worsening for western Arizona, southern Nevada, and southeastern California, as well as the western Great Lakes. Check out the USFS site for definitions of the different dead fuel moisture classifications .

According to the USFS Wildland Fire Assessment System, at the beginning of the month, the only moderate–to–high Keetch–Byram Drought Index (KBDI) values were present in central Washington, Arizona, and the Great Basin. While, the KBDI was low for the eastern two–thirds of the country. Moderate–to–high values were present for central Washington, Nevada, Utah, and southern Arizona. By month’s end higher KBDI values were appearing across the Gulf Coast, with improving values across Washington. At the end of April KDBI values continued to increase across the Gulf Coast, with deteriorating conditions along the Southeast coast. The KBDI remained high for Nevada, northern Utah, southern Arizona, and central New Mexico.

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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