The centre says conditions associated with a tropical storm are expected to affect Queens, Shelburne and Yarmouth counties.

The risk of tropical storm can bring gales of 63 to 117 kilometres per hour.

The centre says confidence is increasing hurricane Earl will move into southern Nova Scotia Saturday morning bringing high winds and heavy rain.

"It is very likely that high wind and heavy rain will affect the Maritimes on Saturday," the centre says in its latest statement on the storm.

Ocean swell from the storm is expected to reach the Nova Scotia coast on Thursday.

"The public should certainly pay close attention regarding weekend plans that may be sensitive to high wind and heavy rain conditions," the centre said.

The hurricane centre says water temperatures south of Nova Scotia that are two to four degrees Celsius above normal could "play into our forecast of intensity as the storm moves over those waters."

But, it says, a Great Lakes trough that will advance through Eastern Canada will "drain Earl of its energy" and cause it to accelerate through Atlantic Canada as it weakens.

Computer models by the centre show a 90 per cent chance of at least gale force winds — in the 60 to 70 kilometre-an -hour range — over land in Nova Scotia. The centre's analysis says there is about a 90 per cent chance of Earl entering Canadian forecast waters as a hurricane, and a 50 to 60 per cent chance of a hurricane making land in Nova Scotia or New Brunswick.

The centre says the potential path of Earl is narrowing as forecasters track its movement.

"Earl could end up as far west as western New Brunswick or as far east as eastern mainland Nova Scotia," it said.

At least one event in Atlantic Canada has been cancelled as a result of the approaching storm.

The promoter for a planned outdoor concert this weekend in Mount Pearl in Newfoundland says safety concerns prompted its cancellation.

Dave Carver says potential effects from hurricane Earl posed difficulties from several perspectives including the safety of concert goers and workers at the site.

The concert was to feature musical acts including Kesha, Goo Goo Dolls, The Fray and others.

He says some of the artists were scheduled to fly into St. John's from the U.S. Eastern Seaboard which has its own problems with the massive storm.