HALIFAX -- With the remnants of one tropical storm already dumping rain across Atlantic Canada on Tuesday, residents were keeping a close watch on three other storms churning their way across the Atlantic.

Special weather statements were issued for tropical depression Gordon, which was expected to deliver up to 40 millimetres of rain to parts of New Brunswick, Nova Scotia and Newfoundland before dissipating on Wednesday.

Meanwhile, hurricane Florence -- the first major hurricane of the season -- is heading toward the U.S. Eastern Seaboard, with forecasters warning it could be one of the most catastrophic storms to hit the region in decades.

"It's still going to be a major hurricane when it arrives along the Eastern Seaboard of the southern U.S. at the end of the week," said Ian Hubbard, a meteorologist with the Canadian Hurricane Centre in Halifax.

"It's getting very close to Category 5 sustained winds over the next 36 hours ... It's still a very powerful, major storm that we have to take seriously."

A Category 5 hurricane can generate sustained winds at 251 kilometres per hour.

A million people have been ordered to leave the U.S. coast and millions more prepared for Florence's predicted arrival on late Thursday or early Friday. Seven-day rainfall totals are forecast to reach 500 millimetres over much of North Carolina and Virginia, and even 760 mm in some places.

However, Hubbard said Florence is not expected to have any impact on Canada, given its predicted track into the U.S. mainland, where it will likely weaken considerably on the weekend.

By the end of the week, a high pressure system is expected to park itself over Atlantic Canada, blocking Florence from a northerly advance and bringing fair weather to the region.

"It's going to keep any of that rain from this system away from us until the beginning of next week," Hubbard said.

As for the two other tropical storms spinning westward across the Atlantic -- Isaac and Helene -- both are also expected to steer clear of Canadian territory.

Tropical storm Isaac is forecast to grow in strength, but it is expected to maintain a steady westward track through the Caribbean Sea into the weekend.

"It's well south of us," said Hubbard. "It's not looking like there will be any impact whatsoever on Canada."

As for hurricane Helene, it is on a predicted track that has the storm swinging to the northeast by Saturday, remaining in the middle of the North Atlantic.

"It's a long way from us," Hubbard said. "It's going to be staying well away from our side of the ocean."

So far this season, there have been nine named storms -- five of them were hurricanes.

In May, the Canadian Hurricane Centre said its forecasters were expecting a "near-normal to above-normal" number of storms this season, a prediction that has proven to be correct -- so far.

Last year, there were 17 named storms. Three of them -- Harvey, Irma and Maria -- were major hurricanes that ravaged Texas, Florida, Puerto Rico and many Caribbean islands.

None of the 17 storms in 2017 made landfall in Canada.

"It doesn't always play out that a busy season in the Atlantic affects us directly," said Hubbard. "Even if you have a slow season, it only takes one storm to really have an impact and cause a lot of damage."

The hurricane season officially runs from June 1 to Nov. 30, when the waters of the Atlantic Ocean are warm enough to produce tropical cyclones.