Over the past three months, seawater temperatures along the California coastline have reached near record warm levels. Scripps Institution of Oceanography has been following the predicted fall/winter El Niño event and its CDIP Waverider buoys, like the one at Diablo Canyon, has confirmed the recent extreme high temperatures in the Eastern Pacific Ocean.
Not only have these warm seawater temperatures allowed the development of numerous Eastern Pacific hurricanes, they have also brought in species of fish not normally seen along the California coastline.
A 50-pound wahoo was caught 12 miles off Dana Point last week. This may have been the first wahoo ever caught off the California coast. This fish is usually found south of Baja California down to the equator. Wahoo is called ono in Hawaii.
Along the San Luis Obispo County coastline, the greatest occurrence of humpback whales that I have ever seen have been gorging themselves on bait balls composed of anchovies, sardines and smelt.
These oceanographic conditions point to a likely El Niño episode this winter. These events tend to produce a greater amount of evaporation and convection out over the ocean, which can force the jet stream further southward, directing Pacific storms toward California. However, another large-scale ocean water temperature cycle in the Pacific could provide another important clue on what this winter will bring.
This large-scale cycle is the Pacific Decadal Oscillation (PDO). It was discovered by Steven Hare, a fisheries biologist who noticed it while studying salmon runs in 1997. The phases of the PDO are called warm or cool phases. Unlike El Niño and La Niña events, which last only about a year or so, the PDO stays in one phase for a much longer period. The cool phase is characterized by lower-than-normal sea-surface temperatures in the north and eastern Pacific.
In the warm, or, positive phase, which lasted from 1977 through 1998 and again from 2002 through 2007, the Eastern Pacific became warmer. Since 2008 through the end of 2013, the PDO has been mostly in the cool phase.
However, this past January saw the PDO gradually change to a positive phase. Since March, the phase has shifted solidly to positive. Since 1950, a positive phase of the PDO combined with El Niño usually produces normal to above-normal rainfall along the Central Coast.
Of course, these are long-range forecasts and there are no guarantees, only time will tell the story. Nevertheless, as I told the Templeton Rotary Club, San Luis Obispo Rams and San Luis Obispo Farm Bureau last week, I never felt more confident in a prediction of normal to above-normal precipitation this rain season.
This leads to the question, when can San Luis Obispo expect its first rain? Overall, rain is most likely around Feb. 15, with precipitation occurring 33 percent of the time. The first rains of the season usually occur in October or November. On Thursday at 4 p.m., call in to “The Dave Congalton Show” on KVEC 920 AM radio and make your prediction. It has to rain at least one-tenth of an inch over a 24-hour period as measured at the Cal Poly Irrigation Training and Research Center to win.
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