Weather Watch

Could record-breaking seawater temps mean typhoons off the California coast?

Ventura voters closely matched the state’s overall results in the November 2016 election, according to the supplement to the statement of vote by the California Secretary of State’s Office.
Ventura voters closely matched the state’s overall results in the November 2016 election, according to the supplement to the statement of vote by the California Secretary of State’s Office. Associated Press file

I don’t know of any place where one can have so much fun with a bag of frozen peas than Santa Catalina Island. Last week, my family and I took the Catalina Express from Long Beach and made the channel crossing to Avalon.

After checking into our hotel, one of the first things we did was snorkel in Lover’s Cove.

As we walked along the shoreline, the seawater was Catalina clear, meaning it was over 50 feet of visibility. As we entered the water, I was expecting it to be chilly; in fact, the last time I snorkeled there many years ago I used a wetsuit. I was startled by the warmth of the sea as we swam out — it seemed more like Hawaii. In about 10 feet of water, I opened the bag of frozen peas, and we got swarmed by Garibaldi — a bright orange fish that is the official marine state fish of California — and kelp bass, more fish than I could imagine.

On our walk back to the hotel, I was curious about the temperature of the water. Turns out, it was record-breaking. Scripps Institution of Oceanography scientists reported all-time high seawater temperatures on consecutive days in early August and on Aug. 8 measured a water temperature of 79.2 degrees Farenheit at the end of the Scripps Pier — the warmest ever recorded since 1916 when seawater temperature recording began there.

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Avalon Bay on Catalina Island. John Lindsey Special to The Tribune

At the same time, numerous Coastal Data Information Program (CDIP) waverider buoys in the Southern California Bight smashed their all-time seawater temperature records. The Scripps Nearshore reached 81.3 degrees, breaking the old record 80.4 degrees set during the very strong El Niño event of 2015. The Torrey Pines waverider buoy also hit 81.3, while the Mission Bay buoy reported 79.9.

Farther north, Camp Pendleton reached 79.2, and both the Long Beach Channel and San Pedro waverider buoys reported 78.4, all record-breaking temperatures for these stations. Honestly, I never thought I would ever see temperatures like these along the California coast.

So, what caused these record-breaking seawater temperatures in the Southern California Bight? Primarily, it’s been the lack of wind in that region and the upwelling it creates, but it is a complex system. The time of the year, the interaction between the California current and Southern California counter current, sub-mesoscale eddies, depth of the mixing layer and thermocline, the sea-surface heat exchange rate with the atmosphere, was it cloudy or overcast, all play a role.

Like the “perfect storm,” It takes many factors coming together at the same time to produce record-breaking seawater temperatures.

With that said, global warming due to the greenhouse gases emitted by human activities has created the ever-rising foundation or baseline of seawater temperatures. You see, the world’s oceans are the principal solar energy collector on Earth. Fortunately, water can absorb massive amounts of heat without a significant increase in temperature. If you put a balloon filled with air over a flame, it will pop in an instant. However, if that balloon is filled with water, the liquid absorbs the heat, and it will not burst. Water’s thermal conductivity (the rate it can remove or add heat) is much higher than air; this makes the ocean’s temperatures an accurate indicator of the amount of global warming that’s occurred.

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The implications of increasing seawater temperatures are too numerous to list, ranging from increasing sea-level due to thermal expansion of the water column, changes in weather patterns to the impacts on the marine ecosystem.

One implication that may be especially troubling are hurricanes. “Tropical cyclone” is the generic term for an organized system of convective clouds that rotate around an area of low pressure over tropical or subtropical waters. For these storms to strengthen and thrive, the seawater temperatures must be at least 80 degrees Fahrenheit or higher. That’s why it’s rare for tropical cyclones to reach the California coastline. The water is too cold.

Nevertheless, it does happen. In 1939, a tropical storm slammed into Long Beach with gale-force winds and torrential rains. Mount Wilson reported 11.6 inches of rain in just 24 hours. In the Los Angeles area, 45 people drowned in the resulting flood, and high winds took 48 souls at sea.

Once these systems reach a sustained wind speed of 74 mph or greater, it’s classified as a hurricane, typhoon or cyclone. The only difference between a cyclone, hurricane or typhoon is the location in which the storm is formed. The term “hurricane” is used in the Atlantic and Northeast Pacific. In the Northwest Pacific, it’s called a “typhoon.” “Cyclones” happen in the South Pacific and Indian Ocean.

As the seawater temperatures continue to increase in the Southern California Bight and reach 80 degrees on a more consistent basis, it does raise the probability of a tropical cyclone reaching the coastline south of Point Conception. Along the Northern and Central California coast, the waters should remain below the 80-degree mark in the foreseeable future.

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John Lindsey’s column is special to The Tribune. He is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter: @PGE_John.
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