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Showers move into the Bay Area as the risk of lightning persists

NO LATER THAN August 17, 6:30 a.m. Light rain was falling in San Francisco Bay Wednesday morning as monsoon moisture entered the region, bringing a risk of thunderstorms and dry lightning.

“There are showers moving through our forecast area right now,” Brooke Bingaman, a National Weather Service forecaster, said at 6:15 a.m. “We’re starting to see lightning and it’s cloud-to-cloud lightning. There were a few cloud-to-surface collisions over the ocean.”

While real raindrops are falling on the Bay Area, the rainfall has been light. Showers are scattered and move quickly, so rainfall totals are low. Palo Alto, for example, measured about 0.03 inches of rain at 6:30 a.m.

A Berkeley resident reported it rained for 15 minutes just before 8 a.m.

Bingaman said the showers were moving south to north and would enter the San Francisco area later this morning and then into the North Bay.

There is about a 15% chance of lightning hitting the ground.

The rainfall comes a day after the Bay Area experienced well above average temperatures, with mercury topping 100 degrees in the interior valleys. In the East Bay, Livermore hit a high of 107, breaking the previous record of 105 on the day in 1951.

Wednesday’s temperatures will still be warm and above normal, but a few degrees cooler than they were on Tuesday. Due to the heat, California’s power grid operator issued a statewide flex alert Asking residents to voluntarily conserve power today, 4-9 p.m., as energy demand is expected to increase and available power sources will tighten due to high temperatures.


There is a slight chance of lightning in the San Francisco Bay Area Tuesday evening and Wednesday morning. In this file photo, lightning pours over the San Francisco-Oakland Bay Bridge as a storm passes over Oakland, Calif., Sunday, Aug. 16, 2020.

Noah Berger/Associated Press

August 17, 4:28 p.m. Forecasters in the San Francisco Bay Area warned of the possibility of dry lightning Tuesday night and Wednesday morning amid a spell of warm weather.

The National Weather Service released a weather update Tuesday afternoon, saying monsoon humidity rising northward could trigger thunderstorms that are more likely to bring lightning than rain.

While the risk of thunderstorms is low at 15%, Meteorological Service meteorologist Crystal Oudit told SFGATE the stakes are high in hot weather and dry summer conditions.

“Even though it is a low probability, it is a high impact situation as a strike could cause a forest fire,” Oudit said over the phone.

Oudit said central California, including Monterey and San Benito counties, would see a chance of thunderstorms Tuesday evening, while the Bay Area would be more likely to be hit early Wednesday morning.

The weather update marked a shift in the forecast, as meteorologists this morning said weather patterns showed there was no chance of thunderstorms developing over the San Francisco Bay Area. Forecasters said if a stray thunderstorm forms, it will occur over the Pacific Ocean. It is not uncommon for forecasts to shift and change.

The thunderstorm warning comes on the same day that two years ago saw a barrage of lightning across northern California that triggered hundreds wildfires in northern California, including the SCU, LNU and CZU Lightning Complex fires in the Bay Area.

The Weather Service said it was not issuing a red flag warning today of a severe fire risk because the risk of lightning is so low.

The even bigger weather story today is the heat, as inland areas of the Bay Area soar into the triple digits with a ridge of high pressure across the region. From 3:30 p.m., Oakland has been 87, Santa Rosa 97, Livermore 105, Concord 102 and Vacaville 106.

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