The National Weather Service has issued a red-flag warning for high-elevation areas in the Bay Area due to the risk of dry lightning sparking fires by the end of the weekend.
Places that are at least 2,000 feet above sea level have a pronounced risk, according to the NWS, which identified parts of the South Bay, East Bay, Peninsula and North Bay — as well as San Benito and Monterey counties — as the focus of the red-flag attention.
A Red Flag Warning has been issued due to the threat of dry lightning starting late Sunday morning and lasting through Monday afternoon.
— NWS Bay Area (@NWSBayArea) July 17, 2021
“The areas we’re most concerned are areas with driest fuels,” said NWS meteorologist Drew Peterson, referring to the spots at risk. “Lower elevations are near normal.”
That’s largely why Peterson and other forecasters are preaching vigilance and watchfulness — keeping an eye out for spot fires and similar activity — but are stressing that it shouldn’t evoke fears of a repeat of last August when dry-lightning sparked an array of massive wildfires throughout the greater Bay Area.
According to the NWS, the areas covered under the red-flag warning include the North Bay Mountains, the East Bay Hills, the Diablo Range, and the Santa Cruz Mountains. The warning is in effect at 5 p.m. Sunday through 5 p.m. Monday.
Farther south, the weather service’s warning goes into effect at 11 a.m. Sunday and lasts through 5 p.m. Monday for the Santa Lucia Mountains in Monterey County, and elevated areas in San Benito County.
Parts of Napa and eastward regions extending through Sacramento and the Central Valley are being subject to a fire-weather watch as well.
Peterson said the chances of a dry-lightning strike in the greater Bay Area is hovering between 15 and 40 percent. He recommends that as a precaution, residents in places covered by the red-flag warning have a go-bag ready for potential evacuation orders.
The catalyst for this weekend’s warnings is a cyclical surge of monsoonal moisture that forms about every three years when a high-pressure system builds over the Four Corners area, where Arizona, Colorado, New Mexico and Utah meet. The system rotates clockwise over the Gulf of Mexico, northern Mexico, Arizona, New Mexico and southern Texas, and sometimes there’s enough moisture for it to reach into California.
Working in the Bay Area’s favor is the marine layer that’s been hanging around the coast for most of the past several weeks, combined with cooler temperatures, which should significantly slow the spread of any fires started by any thunderstorms.
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Author: Robert Salonga