A relatively quiet 2013 Atlantic hurricane season and no sign of tropical activity on the horizon has prompted Weather Services International (WSI) to make a significant reduction to its tropical forecast. WSI forecasters said they now expect 15 named storms to form in the Atlantic Basin, including five hurricanes, one of them major (Category 3 or higher).

In its previous tropical forecast, issued in late August, WSI had said it expected a total of 15 named storms, including eight hurricanes, three of them major, in what it still believed would be a moderately active hurricane season (see Daily GPI, Aug. 23). WSI had called for 19 named storms, including nine hurricanes, five of them major, in a forecast issued prior to the start of the hurricane season (see Daily GPI, April 9). The forecasters subsequently trimmed that prediction to 16/9/4 (see Daily GPI, June 28) and then lowered their numbers to 16/8/3 (see Daily GPI, July 29).

While the consensus forecast had been for above-average tropical storm activity this year, WSI isn’t alone among forecasters in moderating its pre-season predictions. The National Oceanic and Atmospheric Administration (NOAA), which initially said it expected 13-20 named storms, including seven to 11 hurricanes, three to six of them major hurricanes, recently revised its forecast to 13-19 named storms and six to nine hurricanes, three to five of them major (see Daily GPI, Aug. 9; May 24). Those forecast numbers would still make the 2013 Atlantic hurricane season more active than the seasonal average of 12 named storms, six hurricanes and three major hurricanes, NOAA said.

The Colorado State University forecasting team, which had initially estimated 18 named storms, including nine hurricanes, four of them major (seeDaily GPI, April 11), recently said it now expects one less hurricane and one less major hurricane by season’s end.

“With only 30% of the season to go, 2013 has not been particularly memorable so far,” said WSI Chief Meteorologist Todd Crawford. “Of the nine named storms so far, only two have reached weak hurricane status. Clearly, the more bullish preseason outlooks have not panned out this year, even with relatively warm tropical Atlantic Ocean temperatures and a lack of an El Nino event. The lack of instability due to warmer temperatures aloft has likely been one of the reasons for the quiet season.”

Even the reduced numbers in WSI’s latest forecast “may still be too aggressive unless the fundamental background state changes significantly,” Crawford said. “We hope to learn from this outlier season heading into 2014.”

Increased natural gas production from U.S. shale plays in recent years has lessened the potential impact of Gulf hurricanes on prices and supply (seeDaily GPI, Sept. 18).

The 2013 Atlantic Hurricane season, which officially began June 1, ends Nov. 30.