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Hurricane predictions rest on ‘cold water blob’, El Nino’s end

hurricaneseason-sunshinestatenewsBy Nancy Smith From Sunshine State News

In case this one got by you, the first hurricane of 2016, which wasn’t due until after June 1, came and went in January. And some meteorologists predict it is an indication that we can expect a more-active-than-normal hurricane season this year.

Hurricane Alex, with maximum sustained winds of 70 mph, made landfall in the Azores, 900 miles west of Portugal, on Jan. 15. It didn’t last long, but still, Alex was only the second hurricane on record to form in the Atlantic basin during the month of January. The last was in January 1938, according to NOAA’s historical hurricane tracker database.

2015 was a relatively quiet year. The reason this year could be another story is partly because of the expected end of the El Nino weather pattern in the next few months. Weather forecasters have linked the El Nino phenomenon — a warming of the water in the central Pacific Ocean — to weak hurricane seasons in the Atlantic. According to the U.S. Climate Prediction Center, the current El Nino, which started early last year, was the strongest since 1997 and is expected to end in the late spring or early summer.

But, really, there are a jumble of possibilities — conflicting theories — for what could make a virulent storm season or a particularly toothless one.

Most forecasters are expecting 14 named storms — two more than the average number and three more than the 11 that formed in the Atlantic in 2015. Of those 14, eight are likely to be hurricanes and six tropical storms, AccuWeather storm experts announced last week.

But, they said, there’s a big factor that could limit the number of storms in the Atlantic this year. It’s a “cold blob” of water in the northern Atlantic Ocean, east of Newfoundland and south of Greenland, that could push its way south into tropical regions of the ocean, where big storm systems usually form and gain strength.

“This area of colder water started to show up a few years ago and has become larger and more persistent during the past couple of years,” said Dan Kottlowski, an Atlantic hurricane expert for AccuWeather, a private forecaster based in Pennsylvania.

Tropical Storm Risk, a British-based forecaster that predicts cyclone risk for insurance companies and others, however, predict Atlantic hurricane activity will be about 20 percent below the 66-year (1950-2015) long-term average and 15 percent below the 10-year (2006-2015) average.

If the cooler water shifts southward across the eastern Atlantic Ocean, then westward into tropical breeding grounds, AccuWeather’s Kottlowski said, it will generate cooler sea surface temperatures in the region where 85 percent of tropical storm systems develop.

It’s also possible the cold water from the blob could change the makeup of deep ocean currents and affect the water’s salt concentration, AccuWeather forecasters said. If that scenario occurs, it would reverse the pattern of warmer ocean temperatures that has been taking place for the past 20 years.

Since tropical storms and hurricanes thrive in warm ocean water, any period of cooling “would limit tropical development in the Atlantic,” AccuWeather said.

On the other hand, if the cooling does not take place this year, the forecasters said, “sea surface temperatures will remain mostly warmer than normal, likely resulting in a season more active than in the past three years.”

The Atlantic hurricane season runs from June 1 through Nov. 30.

Incidentally, Hurricane Alex was also the first hurricane to occur in the Atlantic in January since Alice in 1955. Alice initially formed into a hurricane on Dec. 31, 1954, but then remained a hurricane into early January 1955.

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