GFMC: Forest Fires in the United States, 26 February 2001

Forest Fires in the United States

26 February 2001

The Operational Significant Event Imagery (OSEI)
reports on 25 February 2001- according to the Associated Press – of two wildfires burning in Florida. The first, having led to the closing of a stretch of Interstate 4 this week, has scorched 10,500 acres so far. The second, probably a spotfire ignited by a wind-blown spark is situated just south of the first one and has grown to 300 acres. Because of heavy cloudiness over Florida, heat signatures from the fires are not visible in satellite imagery so far.
Please check the OSEI Website in the near future.

Environmental News Network:
Florida fire season just beginning
The state is coming off its driest year in over a century, according to National Oceanic and Atmospheric Administration records. Recent freezes also have helped make the state a virtual tinder box.
Fire conditions are worse than in 1998, when blazes burned 500,000 acres statewide. Since Jan. 1, more than 83,000 acres have burned.
For further information see the article posted on 22 January 2001 at the ENN website.

The Florida Division of Forestry gives the following summary of the recent Fire Weather & Fire Danger Information:
“Combining our current rainfall deficits with normal, or below normal rainfall amounts could lead to another potentially severe fire season in 2001. The strong likelihood for a freeze will only adds to this potential. At this point central Florida appears to be the area most likely to experience a severe fire season. This area is currently the hardest hit by drought with little prospect for improvement over the next few months. Despite the end of La Niña, fire potential is likely to remain high for the next several months until a prolonged period of normal to above normal rainfall develops to help ease the drought conditions.”
For further information see: Wildfire Season Forecast of the Florida Division of Forestry

For further information you may also see to the U.S. Drought Monitor.

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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Fire danger maps for the United States for 25 February 2001 (observation time) and 26 February 2001 (forecast)

Dead fuel moisture responds solely to ambient environmental conditions and is critical in determining fire potential. Dead fuel moistures are classed by timelag. A fuel’s timelag is proportional to its diameter and is loosely defined as the time it takes a fuel particle to reach 2/3’s of its way to equilibrium with its local environment. Dead fuels in NFDRS have four timelag classes:
1-hr: Fine flashy fuels, less than 1/4″ (< 0.63 cm) diameter. Responds quickly to weather changes. Computed from observation time temperature, humidity and cloudiness.
10-hr: 1/4 to 1″ (0.63 to 2.54 cm) diameters. Computed from observation time temperature, humidty, and cloudiness, or may be a standard set of “10-Hr Fuel Sticks” that are weighed as part of the fire weather observation.
100-hr: 1 to 3″ (2.54 to 7.62 cm) diameter. Computed from 24 hour average boundary condition composed of day length, hours of rain, and daily temperature/humidity ranges.
1000-hr: 3 to 6″ (7.62 to 15.24 cm) diameter. Computed from a 7-day average boundary condition composed of day length, hours of rain, and daily temperature/humidity ranges.

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10-HR Fuel Moisture

100-HR Fuel Moisture

1000-HR Fuel Moisture

Fuel moisture maps for conterminous US, 25 February 2001

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.
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.

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Keetch-Byram Drought Index Maps for conterminous US, 25 February 2001

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

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30 and 90-day temperature and precipitation forecast maps (February and February to April 2001)
(Source: National Weather Service)

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