Forecasters’ best guess: Active hurricane season ahead

Hurricane experts will lead a seminar to help airport managers prepare for the worst in 2018. Photo: File
Photo: File

Early 2018 hurricane predictions have been announced. Take them with a grain of salt.

Keep in mind, last year at this time, a light 2017 hurricane season was predicted. Then came twice the average number of damaging storms. The Caribbean and some southern U.S. regions are still recovering.

While forecasters are not expecting a repeat of last year’s hurricane season-from-hell, an active season is still in the cards. The Atlantic’s hurricane season officially begins June 1.

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Colorado State University’s forecast is for 14 named storms, seven hurricanes plus three major hurricanes, which is slightly above the long-term average of 12 named storms, six hurricanes and two major hurricanes. In 2017, six major hurricanes came from the Atlantic.

This is the first of four scheduled reports. CSU will provide updates on May 31, July 2 and Aug. 2.

Forecasters are chiefly concerned with the formation of El Niño and with North Atlantic sea surface temperatures.

El Niño

When El Niño conditions are present and ocean temperatures in the tropical Pacific are warm, the Atlantic hurricane season tends to be calmer. The reverse is true when La Niña, the opposite phase, prevails and the tropical Pacific waters are cool.

We don’t yet know which conditions, if any, will take control by the time hurricane season is underway.

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El Niño and La Niña are notoriously difficult to predict. Low-level winds that drive El Niño and La Niña events are usually at their weakest around now, so small changes in the atmosphere can be significant.

That’s why last year’s early forecasts were so off base. Spring 2017 forecast models called for El Niño to develop by the peak of the Atlantic hurricane season. Instead, we ended up with neutral to weak La Niña conditions, which supported the very active season.

CSU anticipates neutral conditions in the tropical Pacific this summer and fall, so the Pacific Ocean may help predict the Atlantic hurricane season.

Sea temperatures

Should the forecast for neither El Niño or La Niña hold true in the Pacific, the configuration of Atlantic sea surface temperatures becomes very important for predicting how active the hurricane season will be. Generally, the presence of warm water in the North Atlantic would tend to portend a busy season.

The western North Atlantic Ocean is currently somewhat warmer than normal, while the far North Atlantic and eastern tropical Atlantic are slightly cooler than normal.

Overall, sea surface temperatures dropped much faster last winter. High sea surface temperatures that dominated the North Atlantic last fall were replaced by cooler waters by late winter and early spring.

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The current pattern is fairly similar what we saw in early last April. But during last spring and summer, the waters warmed much faster than normal across most of the Atlantic. By the peak of the season, the sea surface temperatures were much warmer than normal across most of the tropical Atlantic, fueling mighty hurricanes such as Irma, José and Maria.

Several climate models, including recent predictions from the National Weather Service Climate Forecast System, indicate that the tropical Atlantic will become warmer than normal by August-October. If this holds true, at least a somewhat active hurricane season would be likely.

The 2018 list of storm names will be the same as 2012’s, with the exception of Sandy, which was retired and replaced with Sara.

The names will be: Alberto, Beryl, Chris, Debby, Ernesto, Florence, Gordon, Helen, Isaac, Joyce, Kirk, Leslie, Michael, Nadine, Oscar, Patty, Rafael, Sara, Tony, Valerie and William, followed by the Greek alphabet if necessary.

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Source: Colorado State University

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