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2025 Hazard Mitigation Plan <br />Kittitas Gounty, Washington ffit-%#l <br />Excessive Heat Outlook <br />lssued when the potential exists for an excessive heat event in the next three (3) to <br />seven (7) days. An Outlook provides information to those who need considerable <br />lead time to oreoare for the event. <br />Heat Advisory <br />lssued within 12 hours of the onset of extremely dangerous heat conditions. <br />Generally, an advisory is issued when the heat index values are expected to reach <br />100"F or higher for at least two (2) days, and nighttime air temperatures will not drop <br />below 75'F. <br />Excessive Heat Watch <br />lssued when conditions are favorable for an excessive heat event in the next 24 to <br />72 hours. Generally, a watch is issued when the risk of a heat wave has increased, <br />but its occurrence and timinq is still uncertain <br />Excessive Heat Warning <br />lssued within 12 hours of the onset of extremely dangerous heat conditions. <br />Generally, a warning is issued when the heat index values are expected to reach <br />105'F or higher for at least two (2) days and nighttime air temperatures will not drop <br />below 75'F. <br />DefinitionType <br />Table 4-102. NWS Excessive Heat Advisories <br />A cold wave is likely to accompany winter weather events. However, extreme cold temperatures can <br />occur due to varying atmospheric conditions and may not always coincide with obvious cold weather <br />events (e.9., winter storms, ice storms). When significant cold temperatures are expected, the NWS <br />Pendleton, Oregon Area Forecast Office issues wind chill, freeze and frost advisories, watches, and <br />warnings. Table 4-103 outlines the cold weather products issued by the local NWS Forecast Office. 205 <br />Table 4-103. NWS Cold Weather Advisories <br />4.6.7.4. Probability and Frequency <br />The probability of occurrence for severe weather occurring in Kittitas County is dependent on the type of <br />severe weather. For example, severe weather events in Kittitas County are often related to strong winds <br />associated with winter storms and thunderstorms. Each hazard probability of occurrence is listed below. <br />205 NationalWeather Service. (n.d.).Wind ChillWarning vs. Watch. Retrieved from <br />https ://www.weather.qov/safetv/cold-wind-chill-warninq. <br />lssued when low wind chill index values are expected but will not reach local warning <br />criteria. Extremely cold air and strong winds will combine to generate low wind chill <br />readinos. <br />Wind ChillAdvisory <br />Wind ChillWatch lssued when there is the potential for a combination of extremely cold air and strong <br />winds to create danqerouslv low wind chill index values. <br />Wind ChillWarning <br />lssued for a combination of very cold air and strong winds that will create dangerously <br />low wind chill index values. This level of wind chill will result in frostbite and lead to <br />hvpothermia if precautions are not taken. <br />Frost Advisory lssued when areas of frost are expected or occurring, posing a threat to sensitive <br />veqetation. <br />Freeze Watch <br />lssued when there is a potential for significant, widespread freezing temperatures <br />within the next 24 and 36 hours. A freeze watch is issued in the autumn until the end <br />of the qrowinq season and in the sprinq at the start of the growing season, <br />lssued when temperatures are forecasted to go below 32'F for an extended period <br />of time. This temperature threshold kills some types of commercial crops and <br />residential plants. <br />Freeze Warning <br />Hard Freeze Warning lssued when temperatures are expected to be below 28"F for an extended period of <br />time, killinq most types of commercial crops and residential plants. <br />DefinitionType <br />Chapter 4: Hazard ldentification and Risk Assessment 162