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<br /> <br /> <br />Community Wildfire Protection Plan 35 September 2018 <br />4.2.3.1 Likelihood <br />The model output which best represents wildfire likelihood in Kittitas County is the burn probability <br />output from the FSim modeling done for the Pacific Northwest Region (Oregon and Washington <br />boundaries) risk assessment. It represents a true annual burn probability that considers all possible <br />weather scenarios. This provides a long-term perspective on the relative likelihood of fire for any <br />location in the county in any given year. <br />To produce a map of relative likelihood for the county, the average burn probability for each <br />catchment was calculated, and those averages were classified into four classes of low, moderate, <br />high, and very high. The classes are relative to the distribution of catchment averages only within <br />Kittitas County and are based on quartiles. Therefore, the high and very high classes represent all <br />catchments with an average burn probability value above the county median. The average burn <br />probabilities for watersheds range from 0 to 0.025, with a mean of 0.01. This means, on average, any <br />specific location (i.e., 180-meter pixel) has about a 1 in 100 chance of burning in any given year. <br />4.2.3.2 Susceptibility and Risk <br />Information about susceptibility (or vulnerability) of specific assets is more difficult to map. Neither <br />the Pyrologix nor the PNRS work in Kittitas County provides enough information to adequately <br />represent the susceptibility of communities to wildfire. While the Pyrologix analysis included some <br />datasets that could address community-level susceptibility (e.g., distance to roads, fire stations, water <br />sources, golf courses, etc.), their assessment did not integrate this information with likelihood and <br />intensity data into standard, accepted metrics of risk. The PNRS analysis for the Pacific Northwest <br />Region Quantitative Risk Assessment report did develop abstract estimates of susceptibility (known <br />as response functions) for a variety of natural resources and built assets, but the focus of that <br />assessment was on setting land management and wildfire management priorities on national forest <br />lands. The response function for communities developed in that analysis estimated negative impacts <br />to communities at all levels of fire intensity, but these impacts are vaguely defined and not specific <br />for different types of structures. While information from both assessments provides some insights <br />into wildfire risk, neither facilitates a thorough mapping of risk across the county. <br />Moving forward, susceptibility could be evaluated at multiple scales to facilitate calculation of <br />wildfire risk metrics in and around developed areas in the county. At a community or neighborhood <br />scale, factors similar to those used in the Pyrologix assessment could be used to develop <br />community-level susceptibility ratings. The rating areas could be watersheds, like the catchments <br />used here, but may be more meaningful if they represent specific community or neighborhood <br />boundaries used for planning and fire response purposes. Within each rating area, factors such as <br />ingress/egress, distance to nearest fire station (or average response time), local water supply (e.g., <br />streams, lakes, cisterns), and structure density could inform integrated ratings of community <br />susceptibility to wildfire of different intensities.