Why are spring gales stronger this year? | John Lindsey | John Lindsey

I have received countless emails and social media posts commenting on the stronger than normal northwesterly winds this spring. The San Luis Obispo Air Pollution Control District announced that consistent high winds over the past few weeks have impacted air quality on the Central Coast, particularly in southern San Luis County. Obispo.

Along the northern and central California coast, spring is known for strong and persistent northwesterly winds, but they have been more pronounced this year.

Several days this spring have seen northwesterly wind gusts of over 50 mph at the Diablo Canyon weather tower. On April 30, northwesterly wind gusts reached 59 mph.

This condition has produced large amounts of upwelling and freezing seawater temperatures. Seawater temperatures in Diablo Canyon have so far hovered between 48 and 50 degrees this month. . These winds also mixed the marine/temperature inversion layer, leaving mostly clear skies with lots of sunshine.

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

The first is the record number of storms this year and the southerly prefrontal winds and rains they bring. The first four months of 2022 were the driest on record at Cal Poly since 1869. Cal Poly recorded just 1.5 inches of rain as of May 14. The previous driest start to the year was in 1972, when 2.78 inches fell. So far, Santa Maria Public Airport has seen just 1.7 inches, like Cal Poly, which is also the driest start to the year on record. To make matters worse, May is on track to be completely dry.

This week, the US Drought Monitor dropped much of San Luis Obispo and Santa Barbara counties, except for 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 United States Department of Agriculture.

The scarcity of storms this year is likely linked to the current La Niña, “the drought diva,” according to Bill Patzert – a retired climatologist at NASA’s Jet Propulsion Laboratory in Pasadena – which stubbornly remains in place. As of January 2020, a La Niña or neutral condition – the infamous “El Nothing” or “El Nada” inhabits Niño 3.4 – a region of sea surface temperatures in the central equatorial zone of the Pacific Ocean – as the standard for classify El Niño (SST warmer than normal) and La Niña (SST colder than normal) events. Fortune-telling SST cycles in Niño 3.4 are ranked by their deviation from the three-month average SST.

This week, the Climate Prediction Center reported that “La Niña is favored to continue through the Northern Hemisphere summer (59% chance in June-August), with 50-55% chance through the fall. A few of the climate models predicted that La Niña would persist until early 2023.

El Niño events tend to drive the storm track further south on 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 brings us to the question: what can the California coast expect with a warming climate? One scenario could be more northwesterly winds and, in turn, more upwellings.

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

In recent decades, this assumption seems to be confirmed. Stronger northwesterly winds have reduced the amount of low coastal clouds and the fog and mist they bring. Cloud cover measurements collected at the San Luis Obispo County Airport show a decreasing trend.

None of this is comforting and given the unusually dry conditions across California, all experts are worried about an early and long fire season.

John Lindsey is Pacific Gas and Electric Co.’s Diablo Canyon Power Plant marine meteorologist and media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.

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