Fire Weather Products in the National Blend of Models v3.1

The National Blend of Models (NBM) is a nationally consistent and skillful suite of calibrated forecast guidance based on a blend of both NWS and non-NWS numerical weather prediction model data and post-processed model guidance. The goal of the NBM is to create highly accurate, skillful and consistent gridded forecasts that cover the CONUS, OCONUS, and Oceanic domains. NBM v1.0 was first implemented in January 2016 and subsequent versions have been implemented on a yearly cadence. The next NBM upgrade, NBM v3.1, is scheduled to be implemented in September 2018 at the NOAA Center for Weather and Climate Prediction (NCWCP). NBM v3.1 contains additional forecast elements to support various NWS Service Programs, including fire weather guidance (smoke grids) to assist in Impact-Based Decision Support Services (IDSS). This fire weather guidance will be used by WFO forecasters to support the wildland fire community in predicting the potential of fire onset and/or spread, and determining the ideal timing for prescribed burns. The NBM v3.1 fire weather grids are the first attempt to create nationally consistent fire weather and smoke guidance for this purpose. NBM v3.1 will generate gridded guidance for the following fire weather elements: (1) Mixing Height, calculated using a modified Stull Method (Stull 1991), (2) Transport Wind Speed, (3) Transport Wind Direction, (4) Ventilation Rate, (5) 6-h maximum Haines Index (Haines 1988), and (6) 6-h maximum Fosberg Fire Weather Index (Fosberg 1978). These six new elements will be produced for the CONUS (2.5-km resolution), Alaska (3 km), Hawaii (2.5 km), and Puerto Rico (1.25 km) domains. This guidance will run hourly, with hourly projections 1-36 hours, 3-hourly 39-192 hours, and 6-hourly 198-270 hours. NBM also produces Relative Humidity (RH), Max RH, and Min RH grids to support fire weather applications.