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Verification of Spot Fire Weather Forecasts

Author(s): John D. Horel, Timothy J. Brown
Year Published: 2015

Software was developed to evaluate National Weather Service (NWS) spot forecasts. Fire management officials request spot forecasts from the NWS to provide detailed guidance as to atmospheric conditions in the vicinity of planned prescribed burns as well as wildfires that do not have incident meteorologists on site. A multi-year set of spot forecasts of maximum temperature, minimum relative humidity, and maximum wind speed were compared to nearby surface observations as well as gridded values from the NWS National Digital Forecast Database (NDFD). Based on spot forecasts nationwide, their skill is higher than that available from the NDFD, with the greatest improvement for maximum temperature (8-10% improvement) and less so for maximum wind speed (2% improvement). Verification using nearby soundings of mixing height, transport wind and Haines Index forecasts indicated that mixing height forecasts exhibited larger errors and tended to be biased towards overforecasting compared to forecasts of transport wind speeds and Haines Index values.

An overarching recommendation of this study is to leave the decisions as to what to verify and how to verify the forecasts in the hands of the forecasters and end users by developing flexible methods to explore the multidimensional nature of the forecasts. Based on qualitative, in-depth interviews with fire practitioners and NWS forecasters, improving accuracy and utilization of spot forecasts requires improving communication between NWS Forecast Offices and fire personnel in the field. In addition, study participants recommended considering to provide forecast uncertainty and forecaster confidence in spot weather forecasts to open the opportunity for fire practitioners to use this information in risk analysis. A number of specific recommendations that would increase the usefulness of spot forecasts include: (1) increase the consistency of the information provided by the spot forecasts, (e.g., isolate quantitative numerical values separately from qualitative alphabetical descriptors); 2) assemble a sizable sample of focused prescribed fire and wildfire case studies to evaluate and verify the forecasts in greater depth; 3) improve the spot request process by allowing the requestor to provide information pertinent for verification (e.g., requested forecast wind level a numerical parameter adjustable by the end user within the request form as well as potential nearby observation locations to compare to the forecast).

A noteworthy aspect of this research has been to facilitate transfer from research to operations of the techniques and web-based tools used to undertake the spot forecast verification (see http://meso1.chpc.utah.edu/jfsp/). Approaches used in this study to verify spot forecasts are being migrated to the operational environment of the NWS Performance and Evaluation Branch.

Citation: Horel, John D.; Brown, Tim J. 2015. Verification of spot fire weather forecasts - Final Report to the Joint Fire Science Program. JFSP Project No. 12-1-05-3. Salt Lake City, UT: University of Utah. 8 p.
Topic(s): Fire Behavior, Weather, Smoke & Air Quality, Smoke & Populations
Ecosystem(s): None
Document Type: Technical Report or White Paper
NRFSN number: 15563
FRAMES RCS number: 21108
Record updated: May 31, 2018