Hurricane Isaac weakened Monday into a tropical storm as it raced over the north Atlantic toward Newfoundland, where the Canadian Meteorological Service upgraded a tropical storm watch to a tropical storm warning.

The warning said winds of about 45 mph with higher gusts could be expected Monday afternoon and evening in the Avalon Peninsula. A tropical storm watch was also issued for the Burin Peninsula and Bonavista Peninsula. Warnings mean tropical storm conditions are expected, while watches mean they are possible.

At 11 a.m. EDT (1500 GMT), Isaac had top sustained winds near 60 mph, down from 75 mph earlier in the day, forecasters said. Tropical storms have winds of at least 39 mph, while the threshold for a hurricane is 74 mph.

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The fifth hurricane of the Atlantic hurricane season was was expected to pass over or near southeastern Newfoundland later Monday, according to the National Hurricane Center in Miami.

Newfoundland was buffeted by 100 mph wind gusts from the remnants of Hurricane Florence on Sept. 14.

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Isaac's winds and rain will be comparable to a typical winter storm, said Chris Landsea, a meteorologist at the hurricane center in Miami. But it is too soon to tell how much of an impact Isaac will have, senior hurricane specialist Richard Pasch said.

The Atlantic hurricane season began June 1 and ends Nov. 30.