Hurricane Matthew Remains 'Very Powerful'; Stalls South of Jamaica, Haiti

— -- Hurricane Matthew slowed nearly to a standstill in the Caribbean Sea as a "very powerful" hurricane on Saturday with maximum sustained winds of up to 150 mph, according to the latest advisory from the National Hurricane Center.

Matthew was listed as stationary in the 8 p.m. ET update. Earlier in the day the hurricane center reported that "Some fluctuations in intensity are possible this weekend, but Matthew is expected to remain a powerful hurricane through Monday."

Matthew's sustained winds have decreased in speed by 10 mph since earlier Saturday morning, but ABC News meteorologist Daniel Peck said the hurricane is still moving westward toward Jamaica and Haiti.

"This still looks like a high-impact event for Jamaica and Haiti," Peck said. "We expect conditions to deteriorate in Jamaica and Haiti by Sunday night, early Monday morning, with the worst impacts throughout the day on Monday and into Monday night."

A hurricane watch has been issued for parts of Haiti and remains in effect for Jamaica. Rainfall totals of 10 to 15 inches with maximum sustained amounts of 25 inches are expected across Jamaica as well as southern and southwest Haiti.

Approximately 700 spouses and children of the U.S. personnel at Naval Station Guantanamo Bay were ordered to evacuate by the Commander, Navy Region Southeast. Military aircraft will take the family members to Naval Air Station Pensacola, Florida, until it is safe to return, CNRSE said. Coast Guard personnel at the base will also be evacuated.

The U.S. embassy in Kingston, Jamaica, announced Friday that its consular services section will be closed on Monday and Tuesday in anticipation of the storm.

After the hurricane's expected hit on Jamaica on Monday, Matthew could slam into the eastern part of Cuba with damaging winds, flooding rain and large waves.

The storm was initially expected to lose some strength as it makes landfall in Cuba and moves into the Bahamas. But the latest forecast shows that Matthew could maintain or even strengthen slightly as it passes over the Bahamas by Wednesday or Thursday.

As for the United States, most forecasts keep the weather system east of Florida and only a few show it hitting the Sunshine State by the middle of next week.

"We cannot completely rule out at this point that Matthew could impact Florida or parts of the Southeast coast in some way," Peck said.

Matthew developed very quickly from a tropical wave into a tropical storm with maximum sustained winds of 60 mph around 11 a.m. ET Wednesday. The only other storm that has done this was Hurricane Debbie in 1961, according to ABC News meteorologist Max Golembo.

As the weather system moved over the eastern Caribbean, Matthew brought wind gusts ranging from 50 mph to 60 mph from Dominique to St. Lucia and Barbados. The islands saw heavy rainfall of up to 3 inches, causing landslides and flash flooding. The landslides were so severe that one person was killed by a boulder in St. Vincent.

ABC News' David Caplan, Max Golembo, Melissa Griffin, Daniel Manzo, Daniel Peck, and Catherine Thorbecke contributed to this report.