The National Predictive Services (NPS) has asked the USFS Rocky Mountain Center for Fire- Weather Intelligence (RMC) managed by the WFM RD&A Unit of the USFS Rocky Mountain Research Station (RMRS) to assist with the development of a system of statistical models for predicting the ignition probability & growth potential of significant fires on a national grid based on weather forecasts. The development of this gridded system of predictive equations is planned to proceed in 3 stages. Phase 1 (Oct. 2017 – Dec. 2018) was aimed at developing and partial validation of a high-resolution spatial model for forecasting the probabilities of lightning flashes as a function of 3-D fields of atmospheric parameters stretching from the surface to the tropopause. Lightning is expected to be a strong predictor of fire activity in many parts of the Western US and Alaska. There are 3 main reasons for expending resources on the development of a state-of-the-art system of lightning-forecast equations: >/p>

a. Lightning has been an increasing cause for wildfires in recent years worldwide. Although historically lightning only accounts for about 15% of wildfire occurrences in the USA, lightning-ignited fires burn by far the most territory (~60% of total fire acreage).

b. There is a need for high-resolution operational lightning forecasts of superior skill out to 7-10 days based on long-term climatology that can be harnessed to predict ignition probabilities for naturally occurring wildfires.

c. A gridded Lightning Forecast Model is a prerequisite for the successful development of a new & improved “7-Day Fire-Potential Outlook Products” for Predictive Services.