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.
Fire danger maps for the United States for 29 April 2001 (observation time) and 30 April 2001 (forecast) WAFS
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.
10-HR Fuel Moisture
100-HR Fuel Moisture
1000-HR Fuel Moisture
Fuel moisture maps for conterminous US, 29 April 2001 WAFS
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.
Keetch-Byram Drought Index Maps for conterminous US, 29 April 2001 WAFS
Operational Significant Event Imagery (OSEI)
The following significant events were identified by Satellite Analysis Branch meteorologists and reviewed by the OSEI support team:
NESDIS/OSEI NOAA-14 POES AVHRR LAC satellite image, 26 April 2001.
Heat signatures (red) and smoke (light blue haze) are visible from fires burning in Florida.
(See summary of the recent Fire Weather & Fire Danger Information of Florida´s Division of Forestry below.)
The Florida Division of Forestry gives the following summary of the recent Fire Weather & Fire Danger Information (updated March, 2001):
“Combining our current rainfall deficits with forecasts of below normal rainfall sets the stage for another severe fire season in 2001. To date the state has had over 1,400 fires for more than 100,000 acres. This is not encouraging when historically the majority of acres burn in May and June. Central and southwest Florida appear to be the areas most likely to experience severe wildfire conditions. This area is currently the hardest hit by drought with little prospect for improvement over the next few months.”
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.
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).
30 and 90-day temperature and precipitation forecast maps (May and May to July 2001)
(Source: National Weather Service)