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″ diameter. Responds quickly to weather changes. Computed from observation time temperature, humidity and cloudiness.
10-hr: 1/4 to 1″ 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″ 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 ” 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.
According to the Fire and Aviation Management Morning Report (19 June 2000), current wildfires are burning in: Colorado HIGH MEADOW: This 10,500 acre (4,249 ha) fire is burning on Colorado State Forest Service protected lands 35 miles (56 km) southwest of Denver, near Bailey, Colorado. 50% of the work has been completed for containment of the fire. There are 744 people working on the fire. The number of structures lost has been revised to 58.
BOBCAT: This 10,599 acre (4,290 ha) fire is burning on the Arapaho-Roosevelt National Forest, 12 miles (19 km) west of Loveland, Colorado. 90% of the work has been completed for containment of this fire. 821 people are working on the fire. Nevada HOGAN: This 1,200 acre (486 ha) fire is burning on Bureau of Land Management lands managed by the Elko Field Office, Elko Field Office, 35 miles (56 km) west of Wendover, Utah. 0% of the work has been completed for containment of this fire. 250 people are working on the fire. It is burning in a wilderness study area. Utah BULLION: This 1,000 acre (404 ha) lightening-caused fire is burning on Bureau of Land Management lands managed by the Salt Lake Field Office, 60 miles (96 km) southeast of Wendover, UT. 70% of the work has been completed for containment of this fire. 11 people are working on the fire. California BERRYESSA: This 4,860 acre (1,967 ha) fire is burning 36 miles (57 km) west of Sacramento on land protected by the California Department of Forestry. Two summer homes and six outbuildings have been destroyed. 90% of the work to contain the fire has been done. 648 people are working on this fire. Florida CAMPGROUND: This 700 acre (283 ha) fire is burning on Florida State Division of Forestry administered land near Lakeland, Florida. 36 people are working on this fire. 95% of the work has been done toward containment of the fire.
LOUISE: This complex of 4 fires totals 4,000 acres (1,618 ha) is burning on Florida State Division of Forestry administered land in Alachua County near Gainesville, Florida. 10 people are working on this fire. 95% of the work has been done toward containment. New Mexico LA CUEVA: This 650 acre (263 ha) fire is burning on the Gila National Forest, one and a half mile north of Mora, New Mexico. There 93 people working on the fire. 100% of the work has been done to contain this fire, and this will be the last report unless conditions change.
SALIZ: This 1,001 acre (405 ha) fire is burning on the Gila National Forest, 15 miles (24 km) southwest of Reserve, New Mexico. There are 426 people working on the fire. 100% of the work has been done to contain this fire, and this will be the last report unless conditions change.
VIVEASH: This 28,283 acre (11,446 ha) fire is burning on the Santa Fe National Forest, five miles northwest of Pecos, New Mexico. 80% of the work has been done to contain the fire. There are 328 people working on the fire.
POT MOUNTAIN: This 750 acre (303 ha) fire is burning on Bureau of Land Management lands 30 miles (48 km) northwest of Taos, New Mexico. 90% of the work has been done to contain the fire. There are 28 people working on the fire.
National Interagency Fire Center (NIFC) Wildland Fire Update (19 June 2000)
Good progress was made on large fires during the weekend, and according to an official at the National Interagency Fire Center, current wildland fire activity across the country seems to be normal for this time of year. Fire conditions remain extreme, however, in several areas of the country leading to the potential for increased activity if ignitions sources are present. The number of fires and acres year to date is still well above the 10-year average as fire conditions throughout the Southwest and Southeast led to extreme fire activity early in the season.
Almost 200 new fires were reported from nearly every region of the country yesterday, and there are currently 10 large fires burning in California, Colorado, Florida, Nevada, New Mexico and Utah for a total of 62,167 acres (25,158 ha). So far this year 46,229 wildland fires have burned more than 1.2 million acres (485,622 ha) which is almost half a million acres more than the 10-year average.
Southeast Idaho is expecting strong winds today, and eastern Colorado is bracing for strong winds, low humidities and dry lightning. States throughout the Great Basin will experience cooler and breezy conditions. Florida will be partly sunny with showers and thunderstorms. California will be sunny, hot and dry, with temperatures ranging from the 70s (21-26°C) along the coast to 105 (40°C) in the deserts.
Fig.7. Large Wildland Fires in the United States, 19 June 2000.
(National Interagency Fire Center)
Tab.1. Five-Year Wildland Fire Comparison Statistics Year-to-Date for the United States (19 June 2000)
(Source: National Interagency Fire Center (NIFC)
As of 19 June 2000Number of Wildland FiresArea burntAcresHectars 2000 46,229 1,265,057 511,950 1999 45,240 1,043,065 422,113 1998 27,522 627,441 253,916 1997 30,583 478,778 193,754 1996 62,009 1,890,927 765,231
NIFC Incident Management Situation Report (19 June 2000) Current Situation:
New large fires were reported in the Western Great Basin, Eastern Great Basin and Southern Areas. Initial attack activity was moderate in the Great Basin, Southwest, California, and Southern Areas. Containment goals were reached on three Southwest Area fires. The National Interagency Coordination Center mobilized airtankers, a lead plane, infrared aircraft, engines, crews, and miscellaneous overhead. Very high to extreme fire indices were reported in Arizona, New Mexico, Nevada, Utah, Colorado, California, Kansas, Florida, Georgia, and Mississippi. Outlook:
A RED FLAG WARNING IS POSTED FOR SOUTHEAST IDAHO FOR STRONG WINDS
A FIRE WEATHER WATCH IS POSTED FOR EASTERN COLORADO FOR STRONG WINDS, LOW RELATIVE HUMIDITIES AND DRY LIGHTNING
A trough moving southeast through the Great Basin will bring cooler and breezy conditions. In Nevada, skies will clear today. Utah, Arizona, New Mexico, and Colorado will be partly cloudy with scattered showers and thunderstorms. Some thunderstorms in eastern Colorado could be dry. Temperatures will be in the high 70’s (25°C) in the mountains and up to the 100’s in the lower elevation deserts. Winds will be southwest to northwest at 15 to 25 mph (24-40 km/h) with gusts up to 40 mph (64 km/h). Minimum relative humidities will be 10 to 20 percent in Arizona and New Mexico, and 15 to 30 percent in Utah and Colorado.
Florida will be partly sunny with showers and thunderstorms likely. High temperatures will be from the mid 80’s to the low 90’s (29-34°C). Winds will be southeast to southwest at 5 to 15 mph (8-24 km/h). Minimum relative humidities will be 45 to 55 percent.
California will be sunny, hot and dry. High temperatures will range from the 70’s (21-26°C) along the coast to 105 (40°C) in the deserts. Winds will be southwest to northwest at 10 to 20 mph (16-32 km/h). Minimum relative humidities will be 10 to 20 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%).
Fig.9. Map describing the wildland fire potential (8 June – 6 July 2000) for areas throughout the country.
(Source: National Interagency Fire Center)
20,000 scorched acres reseeded around Los Alamos
(article posted by Environment News Service, 15 June 2000)
LOS ALAMOS, New Mexico – The U.S. Department of Agriculture (USDA) has seeded 20,000 acres of the most sensitive land burned in the Los Alamos area by the Cerro Grande Fire last month. “Our goal is to restore vegetation destroyed by the fire and take other needed emergency erosion control measures,” said Agriculture Secretary Dan Glickman. “We want to get ground cover growing quickly to help protect the land.” The aerial seeding was a cooperative effort. Under the Emergency Watershed Protection program, USDA’s Natural Resources Conservation Service provided $1.2 million in technical and financial assistance, including 750,000 pounds of native grass and small grain seeds. The U.S. Forest Service provided a helicopter and five planes for the seeding.
The effects of the Cerro Grande Fire, which burned 47,650 acres, have increased the potential for storm flow runoff and flooding, particularly in severely burned watersheds. In addition to the aerial seeding effort, more than 250 volunteers from the community worked in other fire stricken areas over the Memorial Day weekend to break up hydrophobic soil, burned so severely that it will no longer absorb water. Volunteer crews are joining several hundred firefighters in rehabilitation activities, including raking, seeding, mulching, placement of log erosion barriers, hazard tree removal and road rehabilitation. Engineers and conservationists are available to provide technical assistance to local residents on erosion control measures and types of vegetation that can be used to reduce soil erosion and flooding in the aftermath of the fires.
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.