Item 26 - Adoption of the City of Santa Ana Emergency Operations Plan

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City of Santa Ana Emergency Operations Plan Part I Basic Plan Extreme Cold - Climate and History The City of Santa Ana, like most of southern California, experiences a generally moderate climate and stable weather patterns. Extreme cold temperatures are rare, but do occur and can pose a threat to populations in the City. The NWS Weather Station located in Santa Ana at Orange County Fire Authority Station 75 (former Santa Ana Fire Department Station 5) has been recording weather data for more than a century. Wintertime low temperatures in the City usually average in the mid to low 50 degrees. Additionally, in the last 100 years (since 1916), the Santa Ana weather station has recorded temperatures below 32 degrees in 37 of those years, and temperatures below 40 degrees in 82 of those years. The most life -threatening consequence of cold temperatures is hypothermia, which is usually associated with extreme cold temperatures. However, even temperatures in this mid-50's range can result in hypothermia for some populations. These include persons without adequate shelter (homeless, persons in sub -standard housing, persons who cannot afford to pay utility bills) or persons with specific risk factors or vulnerabilities (described below). Exposure to wind or rain can also magnify the chilling effect of moderately cold temperatures. National Weather Service Products and Information The National Weather Service defines an Excessive Cold Event based on temperature, wind chill and microclimate factors. The NWS issues a variety of Cold Weather notices when temperatures are forecast to be unusually cold. The guidelines for these notices in Orange County utilize the same Forecast zones defined above, and are: • A Frost Advisory is issued when minimum temperature is forecast to be 33-36 degrees on clear, calm nights. • A Freeze Watch indicates conditions are favorable in the next 12 to 48 hours for a freeze event that meets or exceeds the Freeze Warning criteria. • A Freeze Warning is issued anytime minimum temperature is expected to be 28-32 degrees for a minimum of two consecutive hours at two or more locations within the zone. • A Hard Freeze Warning is issued any time minimum temperature is expected to drop below 28 degrees for a minimum of two consecutive hours at two or more locations within the zone. When coupled with rain or wind, which cause the body to lose heat more quickly, even moderately low temperatures can pose significant health risks. One of the gravest dangers of winter weather is wind chill. The wind chill is based on the rate of heat loss from exposed skin by the combined effects of wind and cold. As the wind increases, heat is carried away from the body at an accelerated rate, driving down the body temperature. Figure 62 Wind Chill Chart Wind Chill Chart -f 62