Forecasters predict below average Atlantic hurricane season

IGINAL 2016_Atlantic_hurricane_season_summary_map

The 2016 season had several Florida and U.S. East Coast threats. Forecasters are now trying to get a handle on what 2017 may look like. (Credit: Wikimedia Commons)

THURSDAY UPDATE: Colorado State University joined other forecasters this week in calling for a “slightly” below normal Atlantic hurricane season.

Hurricane researcher Philip Klotzbach, joined by Michael Bell, issued a forecast for 11 named storms, four hurricanes and two major hurricanes.

The big reason for the reduced forecast totals is roughly the same — a developing El Niño in the tropical Pacific is expected to increase wind shear in the Atlantic, making it more difficult for storms to spin up.

They added: “The tropical Atlantic has anomalously cooled over the past month and the far North Atlantic is relatively cold, potentially indicative of a negative phase of the Atlantic Multi-Decadal Oscillation. We anticipate a below-average probability for major hurricanes making landfall along the United States coastline and in the Caribbean.”

They said Accumulated Cyclone Energy (ACE) would likely be about 75 percent of average, and that the chances of a major hurricane hitting the Florida peninsula — or anywhere on the U.S. East Coast — was 24 percent compared with 31 percent in an average year.

The chance of a hurricane hitting anywhere on the U.S. coast was set at 42 percent, compared with 52 percent in an average year, they said.

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ORIGINAL POST: A below normal 2017 Atlantic hurricane season was predicted Wednesday by two major forecasting agencies as an anticipated El Niño take shape during the summer and fall.

The UK-based Tropical Storm Risk predicted 11 named storms, four hurricanes and two intense hurricanes Category 3 or higher.

AccuWeather also pointed to a potential El Niño while predicting 10 named storms, five hurricanes and three majors. Forecasters said three named storms could make landfall in the U.S. this year.

AccuWeather is concerned with very warm water in the Gulf of Mexico and the Caribbean, which experts said “threaten to support at least one high impact hurricane similar to Joaquin in 2015 and Matthew in 2016.”

TSR said there’s a 51 percent chance that Accumulated Cyclone Energy (ACE Index) — a measure of the strength and duration of all storms during the hurricane season — will be below the average posted for 1950 through 2016.

“Should the TSR forecast for 2017 verify it would mean that the ACE index total for 2013-2017 would be easily the lowest 5-year total since 1990-1994, and would be equivalent to a typical 5-year total experienced during the inactive phase of Atlantic hurricane activity between 1970 and 1994,” they said. “However, it should be stressed that the precision of hurricane outlooks issued in April is low and that large uncertainties remain for the 2017 hurricane season.”

El Niño, a phenomenon characterized by warmer than average water in the tropical Pacific, tends to tamp down tropical activity in the Atlantic by increasing wind shear. Other major factors in storm generation include sea surface temperatures, dry air and atmospheric pressure.

April forecasts almost always show the least amount of skill, with numbers coming more into line with forecasts issued in June and August.

Last year’s April TSR forecast was for 12 named storms, six hurricanes and two major hurricanes. The actual numbers were 15, seven and four.

Forecasts on the eve of hurricane season — which begins June 1 — were closer for all agencies with TSR predicting 17 named storms, Colorado State University predicting 14 and NOAA predicting 10-16.

Colorado State will release its April forecast on Thursday.

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Author: jnelander

Freelance writer and editor

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