Threat of Bay Area dry lightning lessens as hot spell begins to fade

""It's a bit of a miracle," National Weather Service meteorologist Rick Canepa said early Wednesday. "The instability that we expected aloft is interacting with the low pressure off the shore. That's where the coldest air is, and it's a very weak low pressure out there. As a result, it's keeping the volatility over the coastal ocean." Translation: The expected dry lightning and potential for wildfires it creates may be replaced by lightning that's accompanied by soaking rain."

"Or the Bay Area may just get a hint of rain without any of the electricity. It's all a bit too complex at the moment to look too far ahead because of Tropical Storm Mario off Mexico's Pacific Coast, Canepa said. That remnants from that storm are mixing with the dynamic cooling from the low pressure off the coast. "That high water vapor content and cooling could produce more storms," Canepa said. "The wet kind.""

Hot conditions are ending while atmospheric instability interacts with a weak offshore low, confining much of the volatility over the coastal ocean. Expected dry lightning that elevates wildfire ignition risk may instead occur with soaking rain or produce only light rain without thunderstorms. Remnants of Tropical Storm Mario are mixing with dynamic cooling from the offshore low, increasing atmospheric moisture and raising the potential for wet storms. Initial concerns about dry lightning and new ignitions are tempered but not eliminated. Forecast models are being updated hourly; rain is predicted for Santa Cruz Monday and elsewhere by Tuesday as models clarify the pattern.

Read at The Mercury News