Weather is one of the elements of the Fire Triangle conceptual model adopted by the Southern California Wildfire Hazard Center. Meteorological conditions are dominant factors dictating the evolution of wildfires. The main weather parameters controlling the rapid and oftentimes unpredictable spread of wildfires are:
the mean wind speed and direction,
wind gustiness,
air temperature, and
humidity near the surface.
As expected, high temperatures and low humidities accompanied by strong and gusty winds are the most dangerous conditions, which should be carefully monitored with a combination of weather observations and numerical model forecasts. Presently, the horizontal grid resolutions of the numerical weather prediction models from the National Centers for Environmental Prediction (NCEP) are not fine enough to resolve the complex atmospheric features of the highly variable topography of Southern California. The real-time monitoring and forecast of weather conditions are key components in the integrated assessment of the Southern California Wildfire Hazard Center. A downscaling approach is used by the center in order to provide real-time weather forecast products necessary to monitor hazardous environmental conditions for wildfire behavior. The information under the Weather component of the Fire Triangle reflects this approach and is schematically represented as:
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PSU/NCAR MM5:
Weather products from a model domain with 4 km grid spacing |
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Diagnostic Wind Model:
products for Southern California |
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Fire Weather Indexes:
generate Fire Weather Indexes over specific locations in Southern California |
Other fundamental issues in the Weather component of the Fire Triangle are the Validation of the numerical weather forecast products as well as data archiving to create Climatology atlases of the main weather elements (winds, air temperature and humidity) in Southern California with high horizontal grid resolution.
