Forest Fires in the United States: 25 May 2000

Forest Fires in the United States

25 May 2000

Heat signatures (red) are visible from several fires burning in south Florida. A smoke plume (light blue) can also be seen south of Melbourne.

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Fig. 1. NOAA-14 POES AVHRR HRPT multichannel color composite for Florida, 24 May 2000.
(Source: NOAA/OSEI).

Wildland Fire Update for the United States on 24 May 2000 (National Interagency Fire Center (NIFC))
The national response level decreased today as large fires in New Mexico, Florida, Texas, and Oregon near or reach containment. One new large fire was reported from Wisconsin on 23 May, but was contained in the morning of 24 May 2000.

The Wildland Fire Assessment System (WFAS) is a contribution of “The Fire Behavior Research Work Unit”, Missoula (Montana USA). The broad area component of the Wildland Fire Assessment System (WFAS) generates maps of selected fire weather and fire danger components. Fire Danger (Potential) is a normalized adjective rating class across different fuel models and station locations. It is based on information provided by local station managers about the primary fuel model, fire danger index selected to reflect staffing level, and climatological class breakpoints. Low danger (class 1) is green and extreme potential (class 5) is red.

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Fig. 2.-4. Fire Danger Forecast Maps of the United States and Alaska for 24 May (observation time) and 25 May 2000 (forecast).
(Source: Fire Behavior Research Work Unit, Missoula)

The Keetch-Byram Drought Index (KBDI) is a soil/duff drought index that ranges from 0 (no drought) to 800 (extreme drought) and is based on a soil capacity of 8 inches of water. Factors in the index are maximum daily temperature, daily precipitation, antecedent precipitation, and annual precipitation. KBDI = 0 – 200: Soil moisture and large class fuel moistures are high and do not contribute much to fire intensity. Typical of spring dormant season following winter precipitation. KBDI = 200 – 400: Typical of late spring, early growing season. Lower litter and duff layers are drying and beginning to contribute to fire intensity. KBDI = 400 – 600: Typical of late summer, early fall. Lower litter and duff layers actively contribute to fire intensity and will burn actively. KBDI = 600 – 800: Often associated with more severe drought with increased wildfire occurrence. Intense, deep burning fires with significant downwind spotting can be expected. Live fuels can also be expected to burn actively at these levels.

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Fig. 5. Keetch-Byram Drought Index Map of the United States, 24 May 2000
(Source: Fire Behavior Research Work Unit, Missoula)

For further information on the Keetch-Byram Drought Index (KBDI) by Florida’s Division of Forestry / Forest Protection Bureau please refer to Keetch-Byram Drought Index Revisited: Prescribed Fire Applications.

Incident Management Situation Report (24 May 2000)
Current Situation:
One new large fire was reported in the Eastern Area. Crews are approaching containment goals on the remaining large fire in the Southwest Area. Mobilization of resources through the National Interagency Coordination Center was minimal. Very high to extreme fire indices were reported in New Mexico, Arizona, Texas, Utah, California, Colorado, Kansas, and Oklahoma.
A fire weather watch is posted in the Florida panhandle for unstable air, gusty winds and low afternoon relative humidities.
Florida will be partly cloudy with a slight chance of afternoon thunderstorms. High temperatures will be 85 to 95. Winds will be west to southwest at 10 to 15 mph. Minimum afternoon relative humidities will be 35 to 45 percent, and up to 55 percent along the coastlines.
New Mexico will be partly cloudy and breezy with a slight chance of afternoon thunderstorms over the mountains. High temperatures will be 75 to 85 at high altitudes and 90 to 100 in the deserts. Winds will be west to southwest at 15 to 25 mph. Minimum afternoon relative humidities will be 10 to 20 percent.
Arizona will be partly cloudy and very warm. Isolated afternoon thunderstorms may develop over the mountains. High temperatures will be 75 to 90 in mountainous areas and 105 to 115 in the southern deserts. Minimum relative humidities will be 10 to 20 percent in the mountains and 5 to 15 percent at lower elevations.
West Texas will be sunny and hot. High temperatures will be 95 to 105. Winds will be west to southwest at 10 to 20 mph. Afternoon relative humidities will be 10 to 15 percent.

Long-range, 30-day weather forecasts are predicting above-normal temperatures and below-normal precipitation for the southern tier of states from southern California to Florida and throughout the Midwest (see 30 and 90-day forecast maps).

Tab.1. Five-Year Wildland Fire Comparison Statistics Year-to-Date for the United States (22 May 2000)
(Source: National Interagency Fire Center (NIFC)

As of 05/22/00 Number of Wildland Fires Area burnt Acres Hectars 2000 39,865 1,027,072 415,641 1999 38,769 715,714 289,639 1998 20,550 383,148 155,054 1997 25,747 415,500 168,146 1996 54,611 1,419,290 574,366

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Fig. 6. 30 and 90-day temperature and precipitation forecast maps (June and June to August 2000)
(Source: National Weather Service, Boise, Idaho)

The four month period of January through April this year was the warmest such period on record in the United States, the National Oceanic and Atmospheric Administration (NOAA) said Friday. This was the warmest January through April in 106 years of record keeping, according to statistics calculated by NOAA’s scientists working from the world’s largest statistical weather database. The American southwest has been struck by a rash of wildfires in recent weeks, with one blaze sweeping the north rim of the Grand Canyon and another threatening the nation’s largest nuclear weapons lab in Los Alamos, New Mexico. Set deliberately to clear underbrush, the fires spread quickly through the ultra-dry forests.
(Year to Date: Hot and Dry – Forecast: Hot and Dry by ENVIRONMENT NEWS SERVICE (ENS)).

Remarks on Prescribed Burning
At this time of the year prescribed burning operations are conducted routinely.
Fire is an important natural tool for ecosystem management. It can reduce dense vegetation improving wildlife habitat and lessening the potential for large, wildfire disasters. Land managers are directed to prepare a prescribed fire/burn plan for every area of public land that can burn. Some areas require total suppression while others will benefit from a wildland fire. Those areas that will benefit from a fire can be treated by a prescribed fire.
Especially, for the moment, in the southern and southeastern regions of the United States prescribed fire activities will be carried out in the following weeks and months. In this case, fire signals on satellite images can be traced back to this kind of land management activities.

In the Prescribed Fire Position Paper of the Forest Protection Bureau by the Division of Forestry in Florida, prescribed fire activity is described as a land management application that is essential to the practice of forestry, management of wildlife, preservation of endangered plant and animal species, improvement of range conditions and reduction of wildfire damage in the wildland/urban interface areas. While there is general public and landowner concern with increased smoke, reduced air quality, and liability; the general public and landowners benefit significantly from the reduction of devastating wildfire, improved wildlife habitat and forage, preservation of endangered and threatened plant and animal species, and improved management of forest resources. The prospect of severe reductions in the utilization of this management tool is of major concern to Florida’s natural resource managers and conservationists due to the subsequent loss of derived public and private benefits. They suggest the need for legislative attention.

Another report on nation-wide prescribed burning in the U.S.A. was published in  International Forest Fire News No.19 (September 1998).

A set of photographic documents on prescribed burning techniques and objectives in the Southeast can be visited in our photo archive.

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