The chances of an above-normal Atlantic hurricane season have increased, prompting the National Oceanic and Atmospheric Administration (NOAA) to raise its tropical forecast to a total of 12-17 named storms, including five-eight hurricanes, two-three of them major (Category 3 or higher).
NOAA’s updated outlook still indicates a 50% chance of a near-normal hurricane season, but the forecasters said the chance of an above-normal season have increased to 35% and the chance of a below-normal season has decreased to 15% since NOAA’s initial outlook was issued in May. In that forecast, NOAA said there was a 70% chance of nine-15 named storms in the Atlantic Basin, including four-eight hurricanes, with one-three major hurricanes (see Daily GPI, May 25).
“We are increasing the likelihood of an above-normal season because storm-conducive wind patterns and warmer-than-normal sea surface temperatures are now in place in the Atlantic,” said Gerry Bell, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center. “These conditions are linked to the ongoing high activity era for Atlantic hurricanes that began in 1995. Also, strong early-season activity is generally indicative of a more active season.”
The Atlantic hurricane season got off to an early start this year with the formation of tropical storms Alberto and Beryl in May — only the third time that two named storms have formed prior to June 1, the official start of the season, NOAA said. The season’s third named system, Chris, formed southeast of the Canadian Maritimes June 19 and, despite becoming the season’s first hurricane for a few hours on June 21, never threatened the North American mainland. Debby, the fourth named storm of the 2012 season, formed near the Yucatan Peninsula June 23, forcing offshore GOM oil and gas operators to evacuate workers from platforms and shut in production temporarily (see Daily GPI, June 26).
Despite that quick start and its increased forecast numbers, NOAA said an El Nino event, which usually limits tropical storm activity, is likely to develop in the Pacific Ocean this month or next.
“El Nino is a competing factor, because it strengthens the vertical wind shear over the Atlantic, which suppresses storm development,” Bell said. “However, we don’t expect El Nino’s influence until later in the season.”
Forecasters at Colorado State University (CSU) said this week that they expect a total of 14 named storms in the Atlantic Basin this year, including six hurricanes, two of them major, a slight increase from activity they predicted at the beginning of the 2012 hurricane season (see Daily GPI, Aug. 7; June 4) and about the same numbers experienced in a typical season over the past six decades. The 1950-2011 average is 12 named storms, seven hurricanes and three major hurricanes and the 1995-2011 average is 15/8/4.
Last month Weather Services International (WSI) said more named storms than it had previously forecast are likely to form in the Atlantic Basin this year (see Daily GPI, July 25; June 27). The WSI forecast team expects 13 named storms, including six hurricanes, three of them major.
On Thursday the National Hurricane Center (NHC) said Tropical Storm Ernesto, which formed last week, was located on the coast of southern Mexico, about 140 miles east-southeast of Veracruz, with maximum sustained winds of 60 mph. Ernesto, which had been upgraded to hurricane status for a few hours beginning Monday night, was “hanging around near the coast of Mexico…[and was] expected to move inland soon, bringing torrential rains and flooding,” according to NHC, which expected the storm to approach Mexico’s Pacific coast by Friday evening.
The season’s sixth named storm, Florence, was downgraded to a post-tropical remnant low on Monday and by Thursday morning was nothing more than a low pressure trough located a few hundred miles northeast of the northern Leeward Islands. Another low pressure system, which was located about 1,050 miles west of the southern Cape Verde Islands, had a 70% change of becoming a tropical cyclone by the weekend, NHC said.
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