Though downgraded to a Category Three hurricane and still well out to sea, Hurricane Bill could regain Category Four status on Friday as it rolls over warmer ocean waters and on towards Bermuda, the National Weather Service’s National Hurricane Center (NHC) said Thursday.

A hurricane watch, indicating that hurricane conditions are possible within 36 hours, was issued Thursday for Bermuda and Bill was spreading high swells across the western Atlantic Ocean, NHC said. A tropical storm warning was also issued for Bermuda, indicating that tropical storm conditions are expected there within 24 hours.

At 5 p.m. EDT Thursday the eye of the year’s first Atlantic hurricane was about 595 miles south of Bermuda and about 1,080 miles southeast of Cape Hatteras, NC. NHC said it expected Bill to pass over open waters between Bermuda and the U.S. East Coast early Saturday. Maximum sustained winds, which had been near 135 mph on Wednesday (see Daily GPI, Aug. 20), had decreased to near 125 mph with higher gusts. Some strengthening was forecast to occur through Friday. Hurricane-force winds extended outward from the storm’s center as far as 115 miles, and tropical storm-force winds extended outward as much as 260 miles, NHC said.

The hurricane was moving northwest at about 18 mph and was expected to continue on that track through Saturday, with a gradual turn to the northwest and then more northerly on Saturday. Large swells associated with Bill should were affecting the northern Leeward Islands, Puerto Rico and Hispaniola, and should begin to affect Bermuda, the Bahamas, most of the U.S. East Coast and Canada’s Atlantic Maritimes over the next few days. NHC’s five-day tracking forecast showed the hurricane passing just to the east of Bermuda on Saturday. By early Sunday Bill could be affecting conditions on the New England coast, though the body of the storm is not expected to approach the mainland until it is as far north as Nova Scotia, probably some time on Sunday.

AccuWeather.com forecaster Kristina Pydynowski said a dip in the jet stream would steer Bill eastward toward Nova Scotia and Newfoundland.

“How quickly that dip in the jet stream arrives will determine how much of Bill’s wind, rain and waves will batter coastal New England and Atlantic Canada,” Pydynowski said. “The slower the solution, the worse these conditions will be over coastal New England, and the more of Atlantic Canada Bill will pound.” While cooler North Atlantic waters will weaken Bill to a degree, wind and rain associated with the storm could still cause widespread damage as it passes New England and Canada’s Atlantic coast, she said.

Colorado State University (CSU) forecasters on Thursday said that they expect Atlantic tropical storm activity to be “at above-average levels” over the next 15 days. Due largely to the development of an El Nino event, the CSU team recently reduced its tropical storm forecast for 2009 to 10 named storms, including four hurricanes, two of them intense (Category Three or greater).

In a preliminary forecast in December, the CSU team had estimated there would be 14 named storms this year (see Daily GPI, Dec. 11, 2008). By April the forecasters had cut their Atlantic hurricane forecast to 12 named storms (see Daily GPI, April 8) and in June trimmed their forecast to 11 named storms, including five hurricanes, two of them intense (see Daily GPI, June 3).

A total of 16 named storms, including eight hurricanes, five of them intense, formed during the 2008 season. According to the National Oceanic and Atmospheric Administration (NOAA), an average Atlantic hurricane season has 11 named storms, which includes two major hurricanes.

El Nino — the warming of surface temperatures in the central and eastern equatorial Pacific ocean, which can influence the formation of Atlantic hurricanes — arrived at the end of June, according to NOAA scientists (see Daily GPI, July 10). El Nino events, which occur every two to five years and typically last about 12 months, can help suppress Atlantic hurricane activity.

It had been a quiet hurricane season, with no named storms developing until last weekend, when Bill and two lesser tropical storms, Ana and Claudette, formed. Earlier this month NOAA said the quiet start to the hurricane season did not guarantee that the next four months will remain calm (see Daily GPI, Aug. 7). NOAA expects that the Atlantic hurricane season, which began June 1 and runs through Nov. 30, will see near- to below-normal activity, with the calming effects of El Nino continuing to develop. But despite the calm experienced in June and July, the historical peak months of the hurricane season — August to October — could still produce major storms, according to NOAA.

NOAA is predicting fewer storms, with a 70% chance of seven to 11 named storms, three to six of them hurricanes, including just one or two major hurricanes. Forecasters, including Andover, MA-based WSI Corp., have said a new El Nino event, combined with cooler Atlantic ocean temperatures, is likely to make the 2009 Atlantic hurricane season “relatively quiet” (see Daily GPI, July 21). AccuWeather.com Chief Long Range Forecaster Joe Bastardi has also forecast a mild hurricane season (see Daily GPI, May 15).

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