The global models have come into much better agreement on Oscar's eventual recurvature and acceleration, and confidence in the NHC track forecast has increased. Oscar could then become a hurricane by Monday night or Tuesday.
The Miami-based National Hurricane Centre (NHC) said Oscar was expected to continue in a westerly direction overnight, followed by a turn towards the west-northwest by early Monday, with a northwestward motion forecast on Monday afternoon.
Maximum sustained winds have increased to near 60 miles per hour (95 km/h) with higher gusts.
At 1100 a.m. AST (1500 UTC), the center of Subtropical Storm Oscar was located near latitude 27.3 north, longitude 48.4 west.
This system stands a chance to strengthen further into a Category 2 hurricane due to warm water and low wind shear over the Central Atlantic.
The Atlantic hurricane season ends on November 30 and usually peaks in mid-September.
Oscar, which became a tropical storm Saturday, is strengthening and expected to become a hurricane later Sunday but land isn't threatened, according to the National Hurricane Center.