What’s causing all the blustery winds on the Central Coast this spring?

I have received countless emails and social media postings commenting on the stronger-than-normal northwesterly winds this spring. The San Luis Obispo Air Pollution Control District (APCD) announced that consistent high winds over the past several weeks have impacted air quality on the Central Coast, especially in south San Luis Obispo County.

Along the Northern and Central California coast, spring is notorious for strong and persistent northwesterly winds, but it has been more pronounced this year.

Since the start of April through May 15, the northwesterly wind gusts have reached 40 mph or greater on 28 of the last 45 days at the Diablo Canyon Meteorological Tower. That was the most days above 40 mph during this time frame since 1976, when wind records started. On April 30, the northwesterly wind gusts reached nearly 60 mph.

In turn, this condition has produced vast amounts of upwelling and frigid seawater temperatures. So far, seawater temperatures at Diablo Canyon have ranged between 48 and 50 degrees this month. These winds have also mixed out the marine/temperature inversion layer, leaving mostly clear skies with plenty of sunshine.

So why are the infamous gales of spring more persistent and stronger than normal this year?

First is the miniscule number of storms this year and the prefrontal southerly winds and rains they bring.

The first four months of 2022 were the driest on record at Cal Poly since 1869. Cal Poly has recorded only 1.5 inches of rain as of May 15. The previous most-parched start to the year was in 1972 when 2.78 inches fell. So far, the Santa Maria Airport has only seen 1.7 inches, which, like Cal Poly, is also the driest start of any year on record. To make matters worse, May is on track to be completely dry.

This week the U.S. Drought Monitor dropped much of San Luis Obispo and Santa Barbara counties, except the coastal regions, from D2 (severe drought) to D3 (extreme drought) classifications. The Drought Monitor map is updated weekly and is a joint effort of the National Drought Mitigation Center at the University of Nebraska-Lincoln, the National Oceanic and Atmospheric Administration, and the U.S. Department of Agriculture.

The dearth of storms this year is probably related to the current La Niña, “the diva of drought,” which according to Bill Patzert — a retired climate scientist at NASA’s Jet Propulsion Laboratory in Pasadena — remains doggedly in place.

Since January of 2020, a 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 and is 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 three months.

Not only were the northwesterly winds more robust than average along the Central Coast, but the trade winds (easterlies that flow in the Earth’s equatorial region) were stronger than average, which is a classic La Niña condition.

Last week, the Climate Prediction Center reported that “La Niña is favored to continue through the Northern Hemisphere summer (59% chance from June through August), with a 50-55% chance through the fall.” A few of the climate models advertised that La Niña could persist into early 2023. El Niño events tend to drive the storm track further south into the Central Coast, while a La Niña condition often does the opposite, keeping the storm track to the north, which is not good news for precipitation.

Which leads to the question, what can coastal California expect with a warming climate? One scenario could be stronger northwesterly winds and in turn, more upwelling.

Let me explain.

As the Central Valley warms, it could produce a deeper thermal trough, which is often a predominant weather feature during the spring, summer and fall. A deeper trough would create a stronger pressure gradient between the waters off our coast and the interior, producing a higher frequency of occurrence of northwesterly (onshore) winds and cooler air temperatures at the lower levels of the atmosphere.

Over the last few decades, this hypothesis seems to be verifying. The stronger northwesterly winds have reduced the amount of low coastal clouds and the fog and mist they bring. Cloud cover measurements collected from the San Luis Obispo County Airport show a downward trend.

None of this is comforting and given the exceptionally dry conditions all over California, all the experts are anxious about an early and long fire season.

To mitigate the damage from fires, simple tasks such as trimming back trees, shrubs, and bushes and creating defensible space around a home or business can help make neighborhoods and communities safer.

PG&E’s Safety Action Center website offers easy-to-use educational videos and visual guides with tips on how to create defensible space, which is the buffer area between a home and any vegetation or material.

This story was originally published May 17, 2022 at 5:00 AM.