Will El Niño return to Central Coast soon? Or is the ‘diva of drought’ sticking around?

The first three months of 2022 were the driest on record at Cal Poly since 1869. Cal Poly has recorded an inch of rain so far this year.

The previous most-parched start to the year was in 1972, when 1.89 inches fell.

Cal Poly has recorded 13.27 inches of rain this rainfall season, thanks to a wet December, which started July 1, 2021, and ends June 30. That is about 65% of average. The Santa Maria Airport has seen 7.5 inches or 61% of average, while the Paso Robles Airport has recorded 8.56 inches of precipitation or 74% of average.

Due to the warmer than normal temperatures and the historically dry start of 2022, the statewide snowpack water content has fallen to just 29% of average for this date.

Overall, I don’t see much improvement in these numbers as the wettest part of the rainfall season is in our rearview mirror. April only produces about an inch of rain, and unfortunately, the long-range models are not indicating any significant precipitation over the next two weeks.

Many readers have written if we’re likely to see an El Niño condition develop next rainfall season and with it typical or above-average rainfall. Regrettably, the current La Niña, “the diva of drought,” according to Bill Patzert — a retired climate scientist at NASA’s Jet Propulsion Laboratory in Pasadena — remains doggedly in place.

Since January of 2020, an La Niña or neutral condition — the infamous “El Nothing” or “El Nada” has been dwelling in Niño 3.4 — a region of sea-surface temperatures (SST) in the central equatorial area of the Pacific Ocean — as the standard for classifying El Niño (warmer-than-normal SST) and La Niña (cooler-than-normal SST) events.

The fortunetelling SST cycles in Niño 3.4 are categorized by the amount they deviate from the average SST over a three-month period.

This past week, the Climate Prediction Center projected “La Niña is favored to continue into the Northern Hemisphere summer (53% chance during June to August 2022), with a 40-50% chance of La Niña or ENSO-neutral thereafter.”

Which is not good news for precipitation.

Spring makes long-term weather predictions more difficult

Like last year, the United States National Centers for Environmental Prediction (NCEP) ensemble mean forecast is even more pessimistic. It indicates a weak or moderate La Niña condition continuing into January 2023.

With that said, these predictions are often not accurate at this time of the year. Here is why: We are in the so-called “spring predictability barrier.” In spring, the El Niño Southern Oscillation (ENSO) is often transitioning from one phase to another.

For example, a La Niña phase could be decaying and passing through a neutral condition to an El Niño condition, or vice versa. Of course, as you get closer to winter, the models become more accurate because there is less time for inaccurate oceanographic and atmospheric data to be amplified at model initialization.

Neutral or weak La Niña and El Niño conditions typically do not produce reliable seasonal rainfall predictions along the Central Coast, but a moderate, strong, or very-strong El Niño or La Niña classification does more times than not.

Overall, moderate or strong La Niña conditions typically produce lower-than-average winter rainfall. However, there have been a few La Niña years that have created well-above-average rainfall amounts.

With that said, the predicted La Niña may happen within the context of a larger climate event, a resurgence of a cool phase of the basin-wide Pacific Decadal Oscillation (PDO). The PDO is a long-term fluctuation of the Pacific Ocean that waxes and wanes between cool and warm phases approximately every five to 20 years.

During most of the 1980s and 1990s, the Pacific was locked in the oscillation’s warm phase. But conditions changed in 1999, when the cool phase, which resembles a large La Niña, has tended to dominate the Pacific Ocean.

For the past two decades, La Niña events have been more frequent than warmer El Niño occurrences.

“This multi-year Pacific Decadal Oscillation ‘cool’ trend can intensify La Niña or diminish El Niño impacts around the Pacific basin,” Patzert said. “The reemergence of this large-scale PDO pattern tells us there is much more than an isolated La Niña occurring in the Pacific Ocean.

So how do these above or below average seawater temperatures in an area so far away have such a profound effect on California’s weather?

The answer is in the winds, or should I say the upper-level winds.

During an El Niño, the warmer waters in the eastern Pacific produce a more considerable amount of evaporation. As this water vapor ascends into the atmosphere, it often condenses into thunderstorms and releases tremendous amounts of latent heat, further decreasing the atmospheric pressure.

This area of low pressure, in turn, changes the path of the southern branch of the polar jet stream, pulling it farther southward toward the Central Coast. This condition, in turn, brings the storms that produce precious rain and snow.

La Niña does just the opposite; it tends to drive the storm track further northward into the Pacific Northwest, leaving the Central Coast with fewer storms.

PG&E plans Earth Day celebration

The are only a few spots left: Join PG&E Saturday, April 23, from 9 a.m. to 1 p.m. at Montaña de Oro State Park as part of its Earth Day celebration.

Sign up at: https://bit.ly/37FCjtu.