The City of Portland is opening a hurricane shelter at 8 this evening at the Portland Expo for people seeking protection from Hurricane Irene, said Portland Fire Chief Fred Lamontagne at a press conference this morning at Portland’s City Hall.

Evacuees who take shelter at the Portland Expo will be provided with basic necessities and pets will be allowed. Officials reminded residents not to forget to bring prescription medications.

But because the hurricane has weakened and is expected to cross over Maine tomorrow as a tropical storm, the city is holding off from recommending residents evacuate from low-lying areas or from the outer islands.

Still, officials said Irene’s high winds and the potential for flooding pose a serious threat.

“I advise all residents to treat (the storm) as seriously as we are,” said Portland Mayor Nicholas Mavodones at the press conference.  He suggested residents secure outside furniture, shut windows, stock up on enough food and water to last three days and avoid downed power lines.

Lamontagne said outer-island residents should be particularly cautious, noting that ferry service could be interrupted starting Sunday morning because of the storm.

Island residents who wish to leave should gather their belongs and depart by ferry tonight, Lamontagne said.

He added that the city will continue providing storm update over the next several days. Information can be found on the city’s website, www.portlandmaine.gov.

The office of Gov. Paul LePage is scheduled to hold a media briefing at 3 p.m. today to discuss Hurricane’s potential impact. He will be joined by Maine Emergency Management Agency Director Robert McAleer.

Winds from Irene, which meteorologists expect will cross over Maine at about 5 p.m. tomorrow, will likely gust to 60 or 70 mph and could causes extensive damage, said a National Weather Service meteorologist.