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.
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.
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.
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 HRPT satellite image, 27 June 2000
Heat signatures (red) and smoke (light blue) are visible from large fires burning to
the west and southwest of Fairbanks, Alaska. Additional fires may be obscured
by clouds. (Source: NESDIS/OSEI)
Fire and Aviation Management Morning Report (27 June 2000) Alaska CLEAR: This 1,000 acre (404 ha) lightning caused fire is 20 miles (32 km) southwest of Nenana, Alaska burning on lands protected by the Alaska State Division of Forestry, Fairbanks Area. The fire is burning in black spruce and high winds are hampering containment efforts. Nevada ROCK CREEK: This 800 acre (323 ha) fire is 15 miles (24 km) north of Gerlach, Nevada. Habitat for bighorn sheep, cutthroat trout, wild horses, and wild burros is threatened. Two residences and several National Historical Registry buildings are also threatened. 90 % of the work is completed to contain this fire. There are 29 people working on the fire. Oregon 5TH AVE: This 2,400 acre (971 ha) fire is burning ten miles (16 km) north of Vale, Oregon on public lands administered by the Bureau of Land Management. Local rural fire departments are assisting in protecting 11 threatened structures. There are 45 people working on the fire.
HARPHAM: This 1,800 acre (728 ha) fire is burning on public lands administered by the Bureau of Land Management, three miles (5 km) southeast of Maupin, Oregon. 100 % of the work has been completed to contain the fire. This will be the last report unless new activity is reported. Florida MUSE COMMAND: This 1,000 acre (404 ha) fire is burning on lands protected by the Florida State Division of Forestry east of St. Cloud, Florida, in Osceola County. 70 % of the work has been done to contain the fire. There are 15 people working on the fire.
National Interagency Fire Center (NIFC) Wildland Fire Update (27 June 2000)
The nation’s wildland firefighting resources are at full strength and ready to respond to activity as seasonal weather conditions throughout the West increase fire danger. Very high to extreme fire conditions were reported from Alaska, Oregon, Washington, California, Idaho, Nevada, Arizona, New Mexico, Colorado, Wyoming, Florida and Mississippi. Moderate activity is occurring and there are currently five large fires burning in Alaska, California, Florida and Nevada for a total of 3,400 acres (1,376 ha).
Large Wildland Fires in the United States, 26 June 2000.
(Source: National Interagency Fire Center)
Tab.1. Five-Year Wildland Fire Comparison Statistics Year-to-Date for the United States (27 June 2000)
(Source: National Interagency Fire Center (NIFC)
As of 26 June 2000Number of Wildland FiresArea burntAcresHectars 2000 48,232 1,344,133 543,951 1999 46,615 1,124,732 455,162 1998 29,582 689,358 278,973 1997 32,129 625,833 253,265 1996 67,689 2,312,868 935,984
NIFC Incident Management Situation Report (27 June 2000) Current Situation:
New large fires were reported in the Southern California, Northern California and Western Great Basin Areas. Initial attack was moderate in California, Nevada, Alaska, and Florida, and minimal elsewhere. Containment goals were reached on large fires in the Northwest and Western Great Basin Areas. The National Interagency Coordination Center mobilized an airtanker, an air attack plane, engines, radio equipment, crews, and miscellaneous overhead. Very high to extreme fire indices were reported in Alaska, Oregon, Washington, California, Idaho, Nevada, Arizona, New Mexico, Colorado, Wyoming, Florida, and Mississippi. Outlook:
For the western United States there will be scattered thundershowers from the Sierra Nevada’s across the southern Great Basin to Colorado and western Wyoming. Arizona and New Mexico will also have scattered thundershowers. The rest of the western states will be sunny and warm. Temperatures will be in the 80’s and 90’s (26-37°C) at higher elevations and up to 110 (43°C) in the southern deserts. Minimum relative humidities will be up to 40 percent along the coast, and 10 to 25 percent east of the Cascades and in the Great Basin.
Florida will be partly cloudy with scattered thunderstorms. High temperatures will be in the mid 80’s to mid 90’s. Winds will be south to southeast at 5 to 15 mph (8-24 km/h). Minimum relative humidities will be 45 to 55 percent.
Alaska’s interior will be mostly cloudy with a few showers and thundershowers. High temperatures will be from the mid 60’s to the mid 70’s (18-24°C). Winds will be southwest at 5 to 15 mph (8-24 km/h). Relative humidities will be 25 to 40 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).
NIFC Wildland Fire Potential Assessment (8 June to 6 July 2000): ALASKA – Potential: normal. Temperatures have been below normal and precipitation has been above normal for the last six weeks. May was the second coolest in the past 35 years, and green-up was a week or more later than usual. Currently south-central Alaska has the greatest fire potential. Thunderstorm activity should increase later this month and cause a normal amount of fire activity in the interior. NORTHWEST – Potential: Below normal to normal. Temperatures and precipitation have been normal for the past month. Live fuel moistures are above average and have been measured at 121% in central Oregon to 131% in eastern Washington. 1000 hour dead fuel moistures have been above normal in most of the area and generally are being measured from 28% in the west to 17% in the eastern regions. Low potential for fire occurrence and severity is expected for most of the area. In the lower elevations of eastern Washington and Oregon, predicted warmer and drier than normal weather conditions will lead to a normal potential for fires. CALIFORNIA – Potential: Normal to above normal. Precipitation has been below normal and temperatures have been above normal in southern California. In the north both temperature and precipitation have been normal. Some moderate drought conditions still exist in southern California. 1000 hour fuel moistures are normal for this time of year throughout the area. Precipitation received in June will be critical to determining the rest of the season for northern California. The May pattern of less marine influence on southern California will likely continue through June, promoting the likeliness of above average temperatures and low humidities. NORTHERN ROCKIES – Potential: Normal. Precipitation has been below normal and temperatures have been above normal during the last month in most of the area except for northern Idaho, where both have been normal. Live fuel moisture is below normal east of the Continental Divide. 1000 hour dead fuel moisture is running 9 to 12 percent below normal and is measured at 13 to 21%. Eastern and central Montana are experiencing moderate to severe drought conditions, but wetting rains at the end of May have brought some relief. If normal June rains occur, fire occurrence will be average. GREAT BASIN – Potential: Normal to above normal. Temperatures have been above normal during the past month while precipitation has been normal to below normal through the area. Snowpack is 45 to 80 percent of normal in the higher elevations, and most areas are reporting that they are two to three weeks ahead of normal fire season, because of the mild winter. Frost-killed fuels are a concern in eastern Utah. Fine fuel carryover from the past several years is contributing to increased risk of fire activity in Nevada. 1000 hr fuel moistures were measured at 10 to 25% throughout the Great Basin and are 10% below normal in Nevada. Moderate to severe drought conditions are being reported in both southern Nevada and southern Utah. SOUTHWEST – Potential: Above normal. Precipitation has been below normal everywhere except in southeastern Arizona, where it has been normal. Temperatures have been above normal in all parts of the region, as much as 5 to 8 degrees Fahrenheit. Long range forecasts call for above normal temperatures to persist during this month. Long range outlook indicates above normal precipitation for Arizona and New Mexico. 1000 hour fuel moistures are below normal in the central and southern regions and normal in the north. Live fuel moisture is in the 50 to 90 percent range everywhere except the northern portions of both state where live fuel moistures are measured in the 70 to 110 percent ranges. PDI indicates that moderate to severe drought conditions continue throughout all of Arizona and all except the northeast part of New Mexico. ROCKY MOUNTAIN – Potential: Normal to above normal. Precipitation has been normal to below normal and temperatures have been normal to above normal in the past month. Live fuel moistures have been normal except in southern and western Colorado, where they have been up to 40 percent below normal. 1000 hour fuel moistures are below normal for this time of year at 7 to 12% in the west and 10 to 14% in the east. Fire activity is expected to be above normal in southwestern Colorado and in southwestern Wyoming. Due to the anticipated weather pattern where waves of moisture move through about once a week, fire events should be of high intensity but relatively short duration. EASTERN – Potential: Normal to above normal. Temperatures and precipitation have been normal in most of the Eastern Area, except in the Upper Great Lakes region, where precipitation has been below normal. 1000 hr fuels are being measured in the 19 to 25% ranges, approximately 3% below normal for this time of year. Moderate to severe drought conditions exist in the central Midwest and the upper Great Lakes region. Green-up and increased precipitation over the past two weeks have significantly reduced fire danger everywhere except in the Upper Great Lakes area. SOUTHERN -Potential: Normal to above normal. Temperatures have been above normal and precipitation has been normal to below normal through most of the area last month. Approximately one third of the area has a soil moisture deficit of six inches or more. Long-term precipitation anomalies are substantial over most of the region. Southern Louisiana, Georgia, western South Carolina, and central Florida all report extreme drought conditions. 1000 hour fuel moistures are being measured at 7% in parts of Florida and around 20% in the rest of the area.
Temperatures and Precipitation reflect conditions over the past four to six weeks. The long range forecast is for the next 30 days. Above and below normal is indicated above in the narrative, areas not mentioned fall in the climatology category which means there are equal chances of being below normal(33.3%), normal (33.3%) or above normal (33.3%).
Map describing the wildland fire potential (8 June – 6 July 2000) for areas throughout the country.
(Source: National Interagency Fire Center)
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.