El Niño explainer: How warmer ocean currents could impact Bay Area weather this winter
SAN FRANCISCO -- The National Oceanic and Atmospheric Administration (NOAA) is predicting above average ocean temperatures this winter due to strong El Niño conditions, meaning there is a potential for stronger winter storms in the Bay Area as well.
KPIX Chief Meteorologist Paul Heggen offered up analysis of how the region could be affected in the next few months.
Typically, El Niño can go either way for Northern California. There is no question that El Niño conditions will be in effect with abnormally warm ocean surface temperatures this winter. That is already happening, with elevated water temperatures currently being measured just west of South America, stretching far into the Pacific.
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That is the fingerprint of El Niño. And it is not just the raised temperature of ocean water; it is the effect it has on the atmosphere above those warm oceans. It displaces the typical weather patterns. Heggen said it is like adding a new boulder to a stream: it affects things further downstream.
El Niño conditions rearrange how the jet stream behaves around the rest of the world, particularly over our part of North America.
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As far as the weather typically associated with El Niño conditions during the winter months around the Bay Area, the impacts could go either way. The Bay Area is on the northern edge of the part of North America that usually sees a wetter-than-average weather pattern.
Typically, El Niño winters have a far greater impact on Southern California and the southern U.S. in general as the subtropical jet stream gets stronger. However, this year's outlook does not include a significant chance of wetter than normal conditions for Southern California. It does have an increased chance for wetter than average conditions for the Bay Area,
This is partially due to El Niño's influence, but there were also abnormally warm temperatures elsewhere in the Pacific, the Atlantic, and the Indian Ocean building up, largely due to the impact of climate change. That is altering the typical El Niño pattern, displacing the band of wetter weather a bit farther north.
This does not mean a repeat of last year's barrage of bomb cyclones and atmospheric rivers. Rather, it is a relatively modest signal toward wetter than average conditions. Locals should keep in mind that just 1/100th of an inch would qualify as above average.
So the end result could be significantly above or just barely above typical wintertime precipitation across the Bay Area. It will bear watching as the situation evolves over the coming months.
