"I have been amazed at the strong offshore winds that can occur in and around Morro Bay during this time of year. I've noticed the weather station on top of Hang Glider Hill in Cayucos sometimes hits gusts of 50-plus mph during these offshore events. What is so remarkable is how localized these winds appear to be."

— Karl Schoettler, Visalia

This January, I have received other emails commenting on the variance in the speed of these Santa Lucia (northeasterly) winds from one location to another.

During winter dry spells, I have seen Pacific Gas & Electric Co.'s Twitchell Reservoir weather station report northeasterly wind gusts exceeding 50 mph, while Santa Maria is dead calm a short distance away.

It is much easier to predict the wind speed coming off the ocean with no obstructions than coming from the land. Due to the Santa Lucia, Caliente, La Panza mountain ranges in San Luis Obispo County and the Sierra Madre, San Rafael and Santa Ynez mountains in Santa Barbara County, wind speeds can be radically different over a short distance and here is why.

To begin with, the direction of the wind is reported by the direction from which it originates on a compass rose. Westerly winds blow out of the west toward the east and are called "onshore." In other words, the air blows from the ocean to the shore. Easterly winds blow from the east to the west and are called "offshore" winds — the air that blows from the land to the sea.

Over the decades, I have often been told that the terms "onshore" and "offshore" as applied to winds are confusing in two ways: The terms are vague and fuzzy in themselves — "offshore" sounds like it could be inland — and especially so since those terms don't define the perspective from which the winds are considered.

Due to the topography of the Central Coast, offshore winds are typically downslope winds, which are technically called katabatic winds, from the Greek word katabatikos, which means "going downhill."

Traditionally, according to wind data recorded at Diablo Canyon Power Plant's meteorological tower, the winds blow about 60% of the time out of the northwest quadrant along the Pecho Coast. The winds blow approximately 12% of the time out of the northeast quadrant and about 23% out of the southeast quadrant. The other 5% of the time, the winds are spread evenly across the rest of the cardinal headings.

Northeasterly Santa Lucia winds are more common during dry years, while wet years will see more prefrontal southeasterly winds.

This January, high-pressure systems over the Great Basin have been persistent, perhaps due to the current La Niña condition, which tends to push the jet stream/upper-level winds further northward into the Pacific Northwest. Historically, this tends to lead to below-average rainfall for the Central Coast.

These gusty Santa Lucia (northeasterly) winds are often low-level winds associated with canyons, passes and gaps in the coastal mountain ranges.

If the canyon is orientated toward the northeast, the Santa Lucia winds are funneled and accelerated down the canyons like a Venturi. If the winds shift out of the north or east, even by a few degrees, the winds can rapidly decrease from area to another. Naturally, if the pass is orientated in a northerly direction, winds out of the north can be accelerated, while easterly winds can be blocked.

This is one of the main reasons wind speeds can be radically different from one location to another over a short distance in the coastal regions of the Central Coast.

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


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