(CNN) -- A tropical weather system has moved into the Atlantic from the Caribbean and is near the southeastern Bahamas, according to the National Hurricane Center. But the chance the system will become a tropical depression or storm is somewhat less than before.
The center now says the system has a "medium" chance of developing into a depression or storm over the next two days. It puts the odds at 40 percent.
It's still causing drenching rain and gusty winds for several hundred miles to the east, affecting the Virgin Islands, Puerto Rico, Haiti and the Dominican Republic.
The severe weather will probably spread over the Bahamas and Turks and Caicos during the next couple of days, possibly causing life-threatening flash floods and mudslides in mountainous areas, the forecast said.
And as the system moves generally westward, at 10 to 15 miles an hour, a big question is how it will affect efforts to contain the oil spill in the Gulf of Mexico.
CNN Meteorologist Sean Morris says forecast models show the tropical wave moving into the Bahamas and across southern Florida this weekend and then re-emerging in the northeastern Gulf.
U.S. and BP officials are contemplating trying to permanently seal the crippled well by pumping mud into it through a technique called "static kill," but the timing could be influenced by what the weather does.
Bad weather could send ships at the well site back to shore. It also could disrupt booms intended to keep the oil from reaching shore and send skimming ships that collect oil on the surface back to port.
Retired Coast Guard Adm. Thad Allen, who's in charge of the U.S. effort, says that if the system becomes a storm, containment and work on a relief well, considered the permanent solution, could be thrown off schedule anywhere from 10 to 14 days.
Meanwhile, Caribbean islands have been coping with a deluge of rain. Melina Simeonides, a spokeswoman for Puerto Rico Emergency Management, said the weather forced some road closures. Video from CNN's Univision affiliate in the U.S. territory showed streets overwhelmed by rushing water and some giant sinkholes.
CNN'S Jackie Castillo contributed to this report