Weather Watch

All predictions are for a strong El Niño this year

Humpback whales off the San Luis Obispo County coast on Friday. The whales seem to enjoy the relatively warmer waters off the Central Coast this summer.
Humpback whales off the San Luis Obispo County coast on Friday. The whales seem to enjoy the relatively warmer waters off the Central Coast this summer.

Most climatologists will tell you that El Niño reduces hurricane activity in the Atlantic basin but often increases it in the Eastern Pacific.

A strong El Niño event is still being forecast for this year by the International Research Institute for Climate and Society/CPC El Niño-Southern Oscillation Prediction Plume.

An above-normal hurricane season is likely for the Eastern Pacific, according to the National Oceanic and Atmospheric Administration.

In fact, many climatologists and oceanographers are predicting that this year’s event could be on par with the 1997-98 El Niño cycle, one of the strongest we’ve ever seen.

El Niño events tend to produce warmer seawater temperatures in the Eastern Pacific, which can sustain tropical cyclones longer; this in turn can allow these tempests to journey further northwestward out over the Pacific.

If they travel far enough, southerly swells from these cyclones can reach the Central Coast. So far this month, seawater temperatures at Diablo Canyon power plant are averaging 58 degrees or about 3 degrees warmer than normal for July.

El Niño decreases the vertical wind shear, or the change in winds with height, over the eastern tropical Pacific. That condition favors more and stronger tropical cyclones.

So far, El Niño has already affected the wind and rainfall patterns across the equatorial and subtropical Pacific Ocean.

It’s rare for tropical storms to reach the California coastline. 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, while Los Angeles recorded 5.2 inches. Tragically, flooding killed 45 people in the Los Angeles area, and 48 souls were lost at sea.

In contrast, El Niño events tend to reduce the number of hurricanes in the Atlantic basin — the Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.

An El Niño directs the jet stream over the Atlantic basin and creates the hurricane-killing wind shear in the upper atmosphere that often shuts down any tropical cyclones that try to form.

The Atlantic hurricane season runs from June 1 to Nov. 30 each year, with the peak on or about Sept. 10. The Eastern Pacific hurricane season runs a little longer, from May 15 to Nov. 30. So far this year, only two tropical storms, Ana and Bill, have developed in the Atlantic basin.

Tropical storm Bill brought coastal flooding and gusty winds to the Texas coast. Sustained by the warm waters of the Gulf Stream, Ana was an unusual pre-season storm. In fact, it was the earliest tropical cyclone on record to make landfall in the United States when it reached the South Carolina coast.

For the rest of the season, researchers at Colorado State University are predicting a total of eight named storms this season — three of those becoming hurricanes and one becoming a major hurricane — which is well below normal. This is great news for all of us. The deadliest hurricane to hit the United States was the Galveston, Texas, hurricane of 1900. At least 8,000 people died in that storm. The most intense hurricane to hit the United States was the Labor Day hurricane of 1935 that slammed into the Florida Keys. This tropical cyclone, another name for hurricane, had the lowest measured surface pressure ever recorded in North America, reaching an incredible 892 millibars or 26.35 inches of mercury (inHg). The normal pressure reading at sea level is about 1,013 millibars or 29.92 inHg.

To look at it from another perspective, you would have to climb a 3,500-foot mountain to reach the same pressure as was experienced in this hurricane at sea level. Sustained winds were estimated to have reached 200 mph. It was reported that survivors saw the sky fill with sparks, perhaps from small rocks striking each other in the extreme winds.

Hurricane Camille struck the Mississippi Coast in 1969 and was estimated to have 200 mph sustained winds. The highest gust recorded was 213 mph, which actually broke the anemometer used to measure the wind speeds of the storm.

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