CALIFORNIA—The National Weather Service issued a Flash Flood Watch for Sonoma County that will last until 4 p.m. Thursday, January 28.
“The National Weather Service in San Francisco has expanded the Flash Flood Watch to include a portion of western California, including the following area, North Bay Interior Valleys,” the advisory reads.
Experts at the NWS stated that light to moderate rainfall is expected for the Walbridge section of the Lake Napa Unit (LNU) Lightning Complex, which could promote flash floods and debris flows.
“Rain rates and intensities are expected to increase as a secondary boundary sets up over the burn area by mid to late evening,” the advisory states. “Moderate to heavy rainfall is expected to accompany embedded thunderstorms that develop along the boundary this evening through Thursday, January 28 [in the] afternoon. Residents near the Walbridge portion of the LNU Lightning Complex burn area should prepare for potential flooding impacts. Be sure to stay up to date with information from local authorities,” the advisory adds.
The National Weather Service indicated that a flash flood and debris flow are the aftereffects of a wildfire. “Rainfall that is normally absorbed by vegetation can run off almost instantly. This causes creeks and drainage areas to flood much sooner during a storm, and with more water, than normal.”
Another problem that a wildfire can leave behind is “highly erodible” soil which can become a “powerful force of rushing water, soil, and rock, both within the burned area and downstream, can destroy culverts, bridges, roadways, and structures, and can cause injury or death if care is not taken,” the National Weather Service explained on their website.
In case of an evacuation, FloodSmart.gov advises that residents in zones like that of Sonoma County and the Bay Area, should an emergency kit that contains safe, drinking water, canned food, any necessary medicines, flashlights, radio, and blankets.
The County of Sonoma advises its residents to tune the radio to stations 740 AM, 106.9 FM, 91 FM, 100.1 FM, or 89.1 FM for Bilingual/Spanish in order to hear their emergency management alerts.
Know where all evacuation routes are and do not wait to leave when it is necessary, “If possible, leave before local officials issue an evacuation order for your area. Even a slight delay in starting your evacuation will result in significantly longer travel times as traffic congestion worsens,” said Flood Smart.
Go to the County of Sonoma, California’s website, https://socoemergency.org/emergency/maps/, to access their evacuation maps, any recent road closures, and delays.