TAMPA, Fla. (WFLA) -- The National Hurricane Center is monitoring two tropical waves with a chance for development while major Hurricane Gabrielle prompts advisories in the Azores.

Located about 390 miles east-northeast of Bermuda, Gabrielle is moving toward the northeast at about 20 mph.

Its maximum sustained winds are near 140 mph with higher gusts, making it a Category 4 hurricane.

The storm will continue to move away from Bermuda on Tuesday and will begin to approach the Azores on Thursday. A Hurricane Watch is now in effect for all of the Azores.

Gabrielle is expected to gradually weaken during the next couple of days, the NHC said.

Central and western tropical Atlantic (AL93)

A tropical wave located about 1,000 miles east of the Lesser Antilles is showing signs of organization, the NHC said. Environmental conditions are favorable for further development of this system over the next several days.

A tropical depression could form later this week while the system moves west-northwestward to northwestward across the western tropical Atlantic, the NHC said.

The chance of formation in the next 48 hours is 50 percent.

The chance of formation in the next seven days is 90 percent.

East of the Leeward Islands (AL94)

A tropical wave located about 100 miles east of the Leeward Islands could develop later this week.

The tropical wave is producing concentrated, but disorganized showers and thunderstorms. Conditions appear slightly conducive for some development over the next few days as the wave moves westward to west-northwestward at 15 to 20 mph.

According to the NHC, this system is expected to slow down and turn northwestward by the latter part of this week. A tropical depression could form late this week when the system is over the southwestern Atlantic Ocean or near the Bahamas.

The chance of formation in the next 48 hours is 20 percent.

The chance of formation in the next seven days is 60 percent.