The first two months of the 2013 Atlantic hurricane season have been relatively quiet, but the peak mid-August through October portion of the season remains on track for above-normal tropical storm activity, according to forecasters at the National Oceanic and Atmospheric Administration (NOAA).
"Our confidence for an above-normal season is still high because the predicted atmospheric and oceanic conditions that are favorable for storm development have materialized," said Gerry Bell, lead seasonal hurricane forecaster at NOAA's Climate Prediction Center. "Also, two of the four named storms to date formed in the deep tropical Atlantic, which historically is an indicator of an active season."
In an updated Atlantic hurricane season outlook released Thursday, NOAA forecasters said they expect a total of 13-19 named storms to form in the Atlantic Basin this year, including six to nine hurricanes, three to five of them major (Category 3 or higher). That's down marginally from NOAA's initial tropical forecast of 13-20 named storms, including seven to 11 hurricanes, three to six of them major (see Daily GPI, May 24).
"The conditions in place now are similar to those that have produced many active Atlantic hurricane seasons since 1995, and include above-average Atlantic sea surface temperatures and a stronger rainy season in West Africa, which produces wind patterns that help turn storm systems there into tropical storms and hurricanes," NOAA said.
Motivating the slightly lower forecast is a decreased likelihood that a La Nina event will develop in the Pacific, the lack of hurricanes through July, more variability in the wind patterns across the tropical Atlantic and slightly lower hurricane season model predictions, the forecasters said.
The consensus forecast has been for above-average tropical storm activity this year, but several forecasters have lowered the number of storms in their pre-season forecasts. The Colorado State University (CSU) forecasting team, which had initially estimated 18 named storms, including nine hurricanes, four of them major (see Daily GPI, April 11), last week said they now expect one less hurricane and one less major hurricane by season's end.
"We continue to anticipate an above-average season in 2013, although we have lowered our forecast slightly due to anomalous cooling in the eastern subtropical and tropical Atlantic," the CSU team said. "We expect an above-average probability of United States and Caribbean major hurricane landfall."
Forecasters at Weather Services International have twice trimmed their tropical storm forecast, saying recently that they expect 13 named storms, including eight hurricanes, three of them major, after initially predicting 16 named storms, including nine hurricanes, four of them major (see Daily GPI, July 29; June 28).
The first named storm of the season, Tropical Storm Andrea, formed in the eastern Gulf of Mexico (GOM) on June 5 and quickly crossed Florida into the Atlantic Ocean, causing little damage as it hurried up the East Coast. Tropical Storm Barry formed almost two weeks later in the southern GOM and made landfall near Veracruz, Mexico. Tropical Storm Chantal formed off the east coast of South America on July 7 but was downgraded to a Tropical Wave well before reaching the Florida coast days later.
The 2012 Atlantic hurricane season produced 19 named storms, including 10 hurricanes, one of them major, continuing a decades-long high-activity era in the Atlantic Basin (see Daily GPI, Nov. 30, 2012). It was the second consecutive year that the mid-Atlantic and Northeast suffered devastating impacts from a named storm (see Daily GPI, Nov. 14, 2012), but it was the seventh consecutive year that no major hurricanes hit the United States. Despite the devastation it brought to New Jersey and New York, Hurricane Sandy was only a Category 2 when it hit land. And Hurricane Isaac was the only storm in 2012 to cause significant disruption to energy interests in the Gulf of Mexico (seeDaily GPI, Sept. 6, 2012).