Tag Archives: AL17

Tropical Storm Ophelia Forms Over Eastern Atlantic

The busy 2017 Atlantic hurricane season continued when Tropical Storm Ophelia formed over the eastern Atlantic Ocean on Monday.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Ophelia was located at latitude 31.5°N and longitude 39.6°W which put it about 845 miles (1355 km) west-southwest of the Azores.  Ophelia was moving toward the northeast at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 1005 mb.

Thunderstorms formed on Monday near the center of a low pressure system which had been lingering over the eastern Atlantic Ocean and the National Hurricane Center designated the system as Tropical Storm Ophelia.  The thunderstorms formed near the eastern side of the center and several bands of showers and thunderstorms formed in the rest of the eastern half of the circulation.  There were fewer thunderstorms in the western half of Ophelia.  The thunderstorms near the center of circulation were generating upper level divergence which was pumping mass away to the east of the tropical storm.

Tropical Storm Ophelia is an environment that is somewhat favorable to intensification.  Ophelia is moving over water where the Sea Surface Temperature (SST) is near 27°C.  It is near the axis of an upper level trough which is oriented east to west over the Atlantic Ocean.  The trough is producing westerly winds which are blowing toward the top of the circulation and those winds are causing some vertical wind shear.  However, since Ophelia is over water where the SST is 27°C, the clouds are not rising as far into the atmosphere as they would if the water was warmer and some of the upper level winds are blowing completely over the top of the circulation of the tropical storm.  So, the vertical wind shear is not as significant as it could be if the top of Ophelia was higher in the atmosphere.  Tropical Storm Ophelia is likely to strengthen during the next several days and it could eventually become a hurricane.

Since Tropical Storm Ophelia is near the axis of the upper level trough, the steering winds are weaker.  The westerly flow is pushing Ophelia slowly toward the northeast.  The orientation of the trough is forecast to change during the next day or two and Ophelia is expected to move more toward the east-southeast.  On its anticipated track Tropical Storm Ophelia is expected to meander over the eastern Atlantic Ocean for several more days.