I’ve had countless emails and social media posts commenting on stronger-than-usual northwest winds this spring. The San Luis Obispo Air Pollution Control District has announced that persistent high winds over the past several weeks have affected air quality on the Central Coast, particularly in southern San Luis Obispo County.
Along California’s northern and central coast, spring is known for strong, continuous northwesterly winds, but it’s been more noticeable this year.
Several days this spring have seen northwesterly winds of over 50 mph in the Diablo Canyon weather tower. On April 30, the northwest winds reached 59 mph.
This condition resulted in huge amounts of cold, flowing seawater temperatures. So far, sea water temperatures in Diablo Canyon have ranged between 48 and 50 degrees this month. These winds have also mixed the sea/temperature inverted layer, leaving a clear sky with plenty of sunshine.
So why are the infamous spring storms more persistent and stronger than usual this year?
The first is the record small number of storms this year and the south frontal winds and rain they bring. The first four months of 2022 were the driest on record for Cal Poly since 1869. Cal Poly had only recorded 1.5 inches of rain as of May 14. So far, Santa Maria General Airport has only seen 1.7 inches, like Cal Poly, which is also the driest start of any year on record. To make matters worse, Mai is on track to dry completely.
This week, the US Drought Monitor dropped much of San Luis Obispo and Santa Barbara counties, except for coastal areas, from D2 (extreme drought) ratings to D3 (extreme drought) ratings. The Drought Watch Map is updated weekly and is a joint effort of the National Center for Drought Mitigation at the University of Nebraska-Lincoln, the National Oceanic and Atmospheric Administration, and the USDA.
The scarcity of storms this year is likely related to the current La Niña, the “drought singer,” according to Bill Batzert — a retired climate scientist at NASA’s Jet Propulsion Laboratory in Pasadena — which remains persistently in place. Since January 2020, the infamous “regret” or “dew” has been La Niña or neutral status inhabiting Niño 3.4 – a sea surface temperature zone in the central equatorial Pacific Ocean – as a criterion for classifying El Niño events (more than Regular SST) and La Niña (cooler than normal SST). Niño’s SST cycles are rated 3.4 by how much they deviate from the mean sea surface temperature over a three-month period.
The Climate Prediction Center reported this week that it “favors a continuation of La Niña during northern hemisphere summer (59% chance during June and August), with a 50-55% chance during fall.” A few climate models have announced that La Niña will continue until early 2023.
El Niño events tend to push the storm’s path south to the central coast, while La Niña often does the opposite, keeping the storm’s path to the north, which is not good news for precipitation.
Which leads to the next question: What can coastal California expect as the climate warms? One of the scenarios could be more northwesterly winds and therefore more upside waves.
As the central valley warms, it can produce a deeper heat sink, which is often the dominant weather feature during spring, summer, and fall. A deeper basin may create a stronger pressure gradient between the waters off our coast and inland, resulting in higher frequency of northwesterly winds (onshore) and cooler air temperatures at lower levels of the atmosphere.
Over the past few decades, this hypothesis appears to be coming true. Stronger northwest winds have reduced the amount of low coastal clouds and the fog and haze it brings. Cloud cover measurements collected from the San Luis Obispo County Airport show a downward trend.
None of this is comfortable and given the exceptionally dry conditions across California, all experts are concerned about an early and long fire season.
John Lindsey is a marine meteorologist for Pacific Gas & Electric’s Diablo Canyon Power Station and media relations representative. Email him at [email protected] or follow him on Twitter @PGE_John.