MIAMI - Tropical Storm Grace seems to be strengthening and conditions are favorable for it to develop more in the next few days.

Forecasters, however, believe about three days from now conditions will change and Grace will face elements that will contribute to her weakening.

The National Hurricane Center issued the following advisory at 4 a.m.:

Grace will be moving through a low-shear environment for the next 36 to 48 hours, which is likely to support additional strengthening while it moves westward over the tropical eastern Atlantic.

Between days three through five, while Grace is moving over the central tropical Atlantic, vertical shear is forecast to increase to over 20 knots and veer from southwesterly to westerly by the end of the forecast period. Such a hostile environment should induce weakening beginning on day three.

The new NHC intensity forecast indicates continued gradual strengthening through 36 hours while the shear is low and shows a slightly higher peak intensity than the previous forecast.

Weakening could be fast once the shear sets in, and the day four and five intensities are unchanged from before.

Deep convection has become better organized during the past several hours, with a more pronounced curved band developing to the west and south of the center. Recent microwave imagery showed a surprisingly well-organized inner core with the low-level center located a little farther south than previous estimates.

At 4 a.m. the center of Tropical Storm Grace was located near latitude 12.4 North, longitude 28.5 West. Grace is moving toward the west near 13 mph and this general motion with a slight increase in forward speed is expected through Monday night.

Maximum sustained winds have increased to near 45 mph with higher gusts. Some additional strengthening is forecast during the next 36 to 48 hours.

Tropical storm force winds extend outward up to 60 miles from the center. The estimated minimum central pressure is 1004 mb (29.65 inches).