Tropical Storm Gabrielle drenching rains pose greatest threat to island nations

(CBS News) Tropical Storm Gabrielle is now pelting Puerto Rico and the Virgin Islands with powerful winds and drenching rain, and is expected to strengthen in the coming days.

The storm is currently right off the southwest coast of Puerto Rico -- a slow-moving mass on the map that is creating big problems with drenching rains, CBS News weather consultant David Bernard explained on "CBS This Morning."

Overall, the biggest effects of Gabrielle will be seen in Puerto Rico, Bernard said, with flooding and, in the higher elevations some mudslides may occur as three to six inches of rainfall are expected, but as much as 10 inches in some areas. Also, parts of the Dominican Republic could see some of that flooding.

In the coming days, the tropical storm expected to move slowly to the northwest through the night and into Friday. On Saturday, the storm will likely be east of Turks and Caicos Islands and north of the Dominican Republic. Then, the storm is expected to shift out to sea, perhaps threatening Bermuda early next week.

However, there's good news for the U.S. East Coast -- the storm is not expected to turn in that direction.

For Bernard's full forecast, watch his "CTM" appearance above.