Examining National Weather Service Spot Forecasts for Prescribed and Wildland Fires

Fire management utilizes National Weather Service (NWS) spot forecasts to help plan prescribed and wildland fires. Fire management officials request spot forecasts from NWS Weather Forecast Offices (WFO's) to provide detailed guidance as to atmospheric conditions in the vicinity of prescribed and wildland fires. NWS spot forecasts were gathered and analyzed from 2010-2013. Part I of this research project examined surface temperature, wind, and relative humidity variables and was completed by Matt Lammers from the University of Utah. Part II examines mixing height, Haines Index, and transport winds from these spot forecasts. NWS spot forecasts that were issued for a location within 50 km of an upper sounding location and valid for the current day or planned ignition time were examined. Mixing height was calculated from the 0000 UTC sounding via the Stull, Holzworth, and Richardson Number methods. Haines Index was calculated at low, mid, and high elevation based on the elevation thresholds of the sounding and spot forecast locations. Transport winds were determined by averaging the wind speed and direction through the mixed layer from the 0000 UTC sounding.

Error, accuracy, and bias statistics are calculated for all of the qualifying NWS spot forecasts. The results are categorized by fire type and region for each of the examined forecast parameters. The results will be used in conjunction with Part I's results to provide a review and possible implementation of NWS spot forecast verification techniques to the NWS Performance Branch.