While a tropical storm watch is in effect for St. Kitts and Nevis, at Pond Hill, Nevis, forecaster Harry W. Hallstrom said, "Isaac is getting ripped apart with wind shear".
A westward motion with a slight increase in forward speed is expected through the end of the week. "The storm is expected to produce total rainfall accumulations of 2 to 4 inches with isolated amounts up [to] 8 inches across Martinique, Dominica and Guadeloupe", the U.S. National Hurricane Center advised Wednesday.
Rainfall of 0.5 to 1.5 inches with isolated amounts to 3 inches are forecast across Puerto Rico and the southern United States Virgin Islands, with up to an inch anticipated across the remaining Windward and Leeward Islands.
Isaac is moving toward the west near 16 miles per hour, and this general motion with a decrease in forward speed is expected for the next few days.
"Life-threatening flash flooding is possible with Isaac".
However, it is not expected to bring the severe weather seen during Storm Ophelia last October, which caused widespread damage and left three people dead.
Hurricane Helene is forecast to weaken over the eastern Atlantic Ocean, and interests in the Azores islands should monitor the storm's progress. In a 2 p.m. advisory, forecasters said sustained winds remained at 60 miles per hour, down from 75 miles per hour Monday.
"A life-threatening storm surge is highly likely along portions of the coastline of SC and North Carolina, and a Storm Surge Warning is in effect for a portion of this area", the National Hurricane Center said Wednesday.
Swells generated by Isaac will begin to affect portions of the Lesser Antilles this afternoon.
After forecast models showed steering currents collapsing as the storm nears the Carolina coast Tuesday, forecasters shifted the track slightly south.
Although Florence was downgraded from Category 4 status, it is still considered an extremely risky storm with maximum sustained winds near 125 miles per hour.