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National Fire Hazard/Potential Maps

The broad area component of the Wildland Fire Assessment System (WFAS-MAPS) is generating National Maps of selected fire weather and fire danger components of the National Fire Danger Rating System (NFDRS). NFDRS computations are based on once-daily, mid-afternoon observations (2 p.m. LST) from the Fire Weather Network which is comprised of some 1500 weather stations throughout the Conterminous United States and Alaska. These observations are reported to the Weather Information Management System (WIMS) where they are processed by NFDRS algorithms. Many of the stations are seasonal and do not report during the off season. WFAS queries WIMS each afternoon and generates maps from the day's weather observations. Each afternoon Fire Weather Forecasters from the National Weather Service also view these local observations and issue trend forecasts for fire weather forecast zones. WIMS processes these forecasts into next-day index forecasts.

• Lightning Ignition Efficiency - Ignition efficiency is calculated by algorithm, using the NFDRS 100 hour fuel moisture and specialized fuel type maps for the western United States to indicate probability of ignition, given occurrence of lightning.
• The experimental fire potential index map uses satellite derived Relative Greenness, an NFDR fuel model map (both 1 km resolution), and an interpolated 10-hour timelag map as inputs to weight the relative influence of live and dead vegetation to fire potential. The scale ranges from 0 (low) to 100 (high). Complete description of the fire potential index.
  • Observed Experimental Fire Potential
  • Forecast Experimental Fire Potential
• Live Moisture Map - portrays experimental live vegetation moisture with values ranging from 50 to 250 percent of dry weight.
• Keetch-Byram Drought Index - 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.
• Visual Greenness - portrays vegetation greenness compared to a very green reference such as an alfalfa field or a golf course. The resulting image is similar to what you would expect to see from the air. Normally dry areas will never show as green as normally wetter areas.