The Canadian Hurricane Centre is having trouble predicting the path of hurricane Leslie because of its slow pace, but the latest bulletins from forecasters suggest the storm will reach Newfoundland by Tuesday or Wednesday.
The centre said Friday that the range of possible tracks was so wide that the threat posed to the province was 30 per cent.
Still, that kind of figure can be misleading, said Chris Fogarty, manager of the centre in Halifax.
"These storms can have a big impact and when you have even a 10 per cent chance of an impact from something that is pretty large then you still need to be concerned," he said in an interview.
"Thirty per cent, in meteorological terms, is pretty high. Newfoundlanders shouldn't take this storm lightly."
Computer models also indicated the threat posed to Nova Scotia had decreased. "But it is by no means zero," the centre said in a statement.
The big storm is expected to gradually intensify over the next two or three days as it interacts with a trough of low pressure. That may sound ominous, but the centre had caveats about that prediction, too.
If Leslie continues to move at a sluggish pace, the storm will likely veer offshore and pose no threat to land, the centre said.
"The computer models are still not likely showing the true range of uncertainty," the statement said. "This is an average of a very broad range."
Meanwhile, hurricane Michael — a Category 3 hurricane that is much smaller than Leslie — was also moving north along a track that appeared to be converging with Leslie's.
"When you have two hurricanes that are approaching each other ... the size of the storms is key," said Mr. Fogarty.
"It's likely that the bigger circulation of Leslie will push Michael further north more quickly. I don't expect a full merging of these systems. But these are rare setups, so our experience in dealing with that is not that high. ... It's not an immediate cause for concern."
Residents of Nova Scotia and Newfoundland are being warned to be cautious along southern coastlines in the days ahead.
Leslie is expected to produce two-metre waves that could rise to three metres as they break near the shoreline, creating dangerous rip currents.