New Alaska Wildfire Smoke Forecast in Time for Fire Season
A new wildfire smoke forecast product for Alaska, developed by the Air Resources Laboratory (ARL), began its experimental testing phase by the National Weather Service (NWS) on May 27th. Forecasts products are posted daily on the National Digital Guidance Database web page. This new product expands the existing Continental United States (CONUS) smoke forecast over Alaska using a finer 12-km resolution North American Mesoscale (NAM) model rather than the coarser resolution Global Forecasting System (GFS) model. The accuracy of the forecasts will be evaluated during the experimental testing phase over the 2008 fire season.
The current operational smoke transport and dispersion forecasts from agricultural burns and wild fires have been produced by NOAA over the CONUS for the last year. ARL’s HYSPLIT dispersion model is run over the entire country once-a-day using the daily 0600 UTC NAM and GFS meteorological forecast. Hourly average output maps of primary PM2.5 air concentration are produced using actual fire locations identified from satellite observations during the previous day. The dispersion simulation consists of two parts, a 24 h analysis simulation run for the previous day and a 48 h forecast simulation. In the operational forecast, fire locations outside of the NAM domain such as Alaska and Central America, use the coarser resolution global model data for their meteorological forecast. In this new experimental version, an independent smoke forecast is run for the Alaska region using a special extract of the NAM forecast. The use of a NAM extract permits a much faster calculation because most of the over-ocean grid points can be excluded thereby speeding up the calculation.
The new wildfire smoke forecast product allows the NWS to provide higher spatial resolution forecasts for Alaska that are comparable to the rest of the CONUS. These higher resolution forecasts are important for capturing the terrain complexity near major population centers in Alaska.