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2021 Multijurisdictional Local Hazard Mitigation Plan homeless for an extended period, and routine services such as telephone or power could be disrupted. Buildings may be damaged or destroyed. Because the County has never experienced a tornado more severe than an EF1, however, such severity is unlikely. Heavy Rain (Atmospheric Rivers) Heavy rain in San Mateo County can have significant impacts, including crop damage, soil erosion, and increased risk of flood. Stormwater runoff from heavy rains can also impair water quality by washing pollutants into water bodies. Soil erosion, particularly along the coast, is a significant concern for San Mateo County, and is further explored in the landslide and flood hazard profiles. The largest impacts from atmospheric river events would be flooding associated with the abundance of rainfall. The severity of this hazard is addressed in the flood chapter of this plan, in Section 11.2.7. Thunderstorms Thunderstorms carry the same risks as heavy rain events, and depending on the type of storm, they can also serve as breeding grounds for tornados, lightning, and heavy winds, increasing risk of injury and property damage (Keller, 2008). Lightning severity is typically investigated for both property damage and life safety (injuries and fatalities). The number of reported injuries from lightning is likely to be low, and County infrastructure losses can equate to up to thousands of dollars each year. The relationship of lighting to wildfire ignitions in the County increases the significance of this hazard. There are no recorded instances of lightning appearing alone (without a storm) in San Mateo County, and any lightning damage is likely to be compounded by other storm damage. PSPS Events The total costs of a PSPS event are not limited to the amount spent by the executing utility; they also encompass the societal harm that comes from losing electricity, which is more challenging to quantify. For residential customers, costs could come from replacing spoiled food, losing air conditioning (particularly for vulnerable populations), emotional distress, etc. For commercial and industrial customers, the main cost comes from lost revenue and production, but also includes the costs of installing backup power. Hospitals may rely on backup generation, and municipal governments might have to coordinate responses without power. When choosing to de- energize, the utility is choosing to create a controlled “disaster” in lieu of risking a larger, uncontrollable line- sparked wildfire, for which they would be liable. These conflicting interests between individual customers, public safety, and fiscal solvency have forced utilities to make difficult choices beyond those typically expected for an electric company (Wharton University, 2020). 14.2.5 Warning Time Meteorologists can often predict the likelihood of a severe storm or other severe weather event. This can give several days of warning time. However, meteorologists cannot predict the exact time of onset or severity of the storm. Some storms may come on more quickly and have only a few hours of warning time. The San Francisco Bay Area Weather Forecast Office of the NWS monitors weather stations and issue watches and warnings when appropriate to alert government agencies and the public of possible or impending weather events. The watches and warnings are broadcast over NOAA weather radio and are forwarded to the local media for retransmission using the Emergency Alert System. 14-16