SAN FRANCISCO (KPIX 5) — You can now call it “The Strongest El Niño In Modern History”.
There are several different ways to measure the strength of El Niño, and we hit a milestone on one of those measuring sticks Monday morning. Looking only at the weekly departure from normal ocean temperatures, ENSO Region 3.4 – the one that means the most to winter weather in California – just hit an all-time high. The ocean temperature in that part of the equatorial Pacific has risen to 3.0 degrees Celsius warmer than average. That’s higher than the peak values for both the 1997-98 event (+2.8 degrees C) and the 1982-83 event (+2.7 degrees C).
El Niño is significant for winter weather in California because it impacts the subtropical jet stream, often directing the wettest of wintertime storms toward us rather than away from us. Historical data shows that the stronger El Niño events have a more profound impact.
Although we don’t know exactly what this will mean for our winter here in the Bay Area, if it’s anything like the other two “very strong” El Niño events, it’ll be rather wet after Christmas. It’s a small sample size, but the average January/February rainfall in those two events exceed 20 inches of rain. That’s more than double what is average for those two months. The latest long-range computer forecast models are indeed calling for above-average precipitation starting in January.
If history repeats itself, it will likely get much wetter in and around San Francisco just after we turn the page to 2016.