Forest Fires in the United States: 26 April 2000

Forest Fires in the United States

26 April 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. 1. & 2. Fire Danger Forecast Maps of the United States for 25 April (observation time) and 26 April (forecast) 2000
(Source: Fire Behavior Research Work Unit, Missoula)

Keetch-Byram Drought Index (KBDI) by Florida’s Division of Forestry / Forest Protection Bureau
John Keetch and George Byram developed the K/B index at the Southern Forest Fire Laboratory to evaluate the effects of long-term drying on litter and duff and subsequently, on fire activity (1968). The index is based on a measurement of 8 inches (20 cm) of available moisture in the upper soil layers that can be used by vegetation for evapotranspiration. The index measure is in hundredths (0.01) of an inch of water and has a range of 0 through 800, with 0 being saturated and 800 representing the worst drought condition. The index indicates deficit inches of available water in the soil. A K/B reading of 250 means there is a deficit of 2.5 inches (64 mm) of ground water available to the vegetation. As drought progresses, there is more available fuel that can contribute to fire intensity.
For further information on the KBDI please refer to Keetch-Byram Drought Index Revisited: Prescribed Fire Applications.

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Fig.3. Keetch-Byram Drought Index Map of Florida, 25 April 2000
(Source: Florida Division of Forestry)

According to the Incident Management Situation Report three categories of fires are distinguished, such as:
1. Fires*
2. Prescribed Fires
3. Wildland Fire Use Fires**

*  This classification corresponds to the category “wildland fires” as defined by the National Interagency Fire Center (NIFC)
** A brief excursion to wildland fire terminology:

Wildland Fires: Fires occurring on any tpye of vegetation, regardless of ignition sources, damages or benefits.
Wildfire: Any uncontrolled wildland fire which (1) may require suppression response, or (2) any uncontrolled wildland fire which meets management objectives and is declared as a Wildland Fire Use Fire (see below) or syn. Prescribed Natural Fire or Prescribed Fire.
Prescribed Fire: Occasionally also called management-ignited fire, or prescribed burning, is a controlled application of fire to vegetation in either their natural or modified state, under specified environmental conditions which allow the fire to be confined to a predetermined area and at the same time to produce the intensity of heat and rate of spread required to attain planned resource management objectives.
Wildland Fire Use Fire: Naturally ignited fire which is managed to achieve resource benefits under close supervision (syn. Prescribed Natural Fire)

Incident Management Situation Report (25 April 2000):

Current Situation:
Initial attack activity and new large fires were reported in the Eastern and Southern Areas yesterday. Numerous units in Arizona and New Mexico reported very high to extreme fire danger. Other states with very high to extreme fire indices included Oklahoma, Texas, Michigan, Wisconsin, and Georgia.
Outlook:
Arizona, New Mexico, and west Texas will be sunny today with high temperatures ranging from around 70 in the mountains to 100 in the southern deserts. Winds will be 5 to 15 mph throughout the region.
Missouri will be sunny in the eastern part, with increasing clouds in the west. Scattered showers will be developing in the southwest portion of the state this afternoon. High temperatures will be in the 60’s. Winds will be northeast to southeast at 5 to 15 mph.

Detailed information and data about fires, prescribed fires, wildland fire use fire and burned areas (24 April 2000) for all geographic areas of the United States can begathered from the Incident Management Situation Report.

Wildland Fire Update (19 April 2000)
The National Interagency Fire Center (NIFC) provides new data of the current wildland fire season in the United States. These data were analysed after different geographic regions. Further, a  five-year wildland fire comparison statistic shows the number and the area of wildland fires from 1996 to 2000.

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Fig.4. Geographic areas and coordination centers
(modified map from National Interagency Fire Center (NIFC)).

Fire suppression forces have battled hundreds of fires during the past 10 days including several large fires in Arizona, New Mexico, Florida, Missouri, Colorado, Kentucky and North Carolina. Severe fire conditions exist in several states throughout the Southwest, Southern Area and the Midwest as unseasonably warm, dry weather persists. Several wildland fires have either destroyed or threatened homes in these areas. Land managers encourage homeowners near the wildlands to take precautions in protecting their homes from wildfires.
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 Fig.5. 30 and 90-day forecast maps).

Tab.1. Five-Year Wildland Fire Comparison Statistics Year-to-Date for the United States (19 April 2000)
(Source: National Interagency Fire Center (NIFC))

As of 04/19/00 Number of Wildland Fires Area burnt Acres Hectars 2000 25,909 664,995 269,114 1999 27,051 422,798 171,100 1998 13,213 229,251 92,775 1997 17,947 312,329 126,395 1996 43,030 1,097,711 444,228

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Fig.5. 30 and 90-day temperature and precipitation forecast maps (April and April to June 2000)
(Source: National Weather Service, Boise, Idaho)

The rest of spring and summer will be warmer than normal in most of the United States, and many Midwest and Great Plains areas will continue to suffer dry days, according to the latest seasonal forecast from the National Weather Service.
The Weather Service also predicts that La Niña, which has dominated global weather patterns for the past two years, will linger until August, when Pacific Ocean temperatures will slowly return to normal.
“La Niña leaves states high and dry” is an article published by the the Environmental News Network (ENN) on 24 April 2000.

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Fig. 6. The National Weather Service predicts many states will experience drier than normal conditions this year
Source: NOAA

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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