Tag Archives: Andrea

Tropical Storm Andrea Forms over the Central Atlantic

Tropical Storm Andrea formed over the Central Atlantic Ocean between Bermuda and the Azores on Tuesday morning.  At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Andrea was located at latitude 36.6°N and longitude 48.9°W which put the center about 1205 miles (1940 km) west of the Azores.  Andrea was moving toward the east-northeast at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1014 mb.

Thunderstorms persisted in parts of a low pressure system over the Atlantic Ocean between Bermuda and the Azores and the U.S. National Hurricane Center designated the system as Tropical Storm Andrea on Tuesday morning.

Thunderstorms were occurring mainly in bands in the northern side of Tropical Storm Andrea.  Bands in the southern half of Andrea’s circulation consisted primarily of showers and low clouds.

Tropical storm force winds extended out 45 miles (75 km) in the southeastern quadrant of Tropical Storm Andrea.  The winds in the other parts of Andrea’s circulation were blowing at less than tropical storm force.

Tropical Storm Andrea will move through an environment that will be unfavorable for intensification of a tropical storm during the next 24 hours.  Andrea will move over water where where the Sea Surface Temperatures are near 23°C.  It will move under the eastern side of an upper level low over the Central Atlantic Ocean.  The upper level low will produce strong westerly winds that will blow toward the top of Andrea’s circulation.  Those winds will cause strong vertical wind shear.  Strong vertical wind shear and cool Sea Surface Temperatures are likely to cause Tropical Storm Andrea to weaken during the next 24 hours.

Tropical Storm Andrea will move around the northern side of a subtropical high pressure system over the Central Atlantic Ocean.  The high pressure system will steer Andrea toward the east-northeast during the next 24 hours.  On its anticipated track, Tropical Storm Andrea will move toward the Azores.

Subtropical Storm Andrea Develops Southwest of Bermuda

Subtropical Storm Andrea developed southwest of Bermuda on Monday afternoon.  An Air Force Reserve Hurricane Hunter aircraft investigated an area of low pressure southwest of Bermuda on Monday afternoon.  The aircraft determined that there was a well defined center of circulation at the surface and the National Hurricane Center designated the system as Subtropical Storm Andrea.  At 11:00 p.m. EDT on Monday the center of Subtropical Storm Andrea was located at latitude 29.5°N and longitude 68.7°W which put it about 300 miles (485 km) southwest of Bermuda.  Andrea was moving toward the north at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1006 mb.

The circulation around Subtropical Storm Andrea was asymmetrical.  Most of the thunderstorms and the strongest winds were occurring northeast of the center of circulation.  Bands in other parts of the circulation consisted primarily of lower clouds and showers and the winds were weaker in those parts of Andrea.  An upper low northeast of the Bahamas was producing southerly winds which were blowing toward the top of the circulation.  Those winds were creating moderate vertical wind shear and the shear was the primary cause of the asymmetrical structure of Subtropical Storm Andrea.  The asymmetrical structure was the reason why Andrea was classified as a subtropical storm.  Winds to tropical storm force extended out about 65 miles (105 km) from the center of Andrea in the northeastern quadrant of the circulation.

Subtropical Storm Andrea will move through an environment marginally favorable for intensification on Tuesday.  Andrea will move over water where the Sea Surface Temperature is near 25°C.  The upper low will continue to cause moderate vertical wind shear, but the low could weaken slightly on Tuesday.  If the upper level winds weaken, then Andrea could get stronger.  Stronger upper level westerly winds could affect Subtropical Storm Andrea on Wednesday.  Those winds will cause stronger vertical wind shear which will weaken Andrea.

The upper level low northeast of the Bahamas will steer Subtropical Storm Andrea toward the north during the next 12-18 hours.  After that time the upper level westerly winds are likely to steer Andrea more toward the east.  On its anticipated track Subtropical Storm Andrea could be near Bermuda in about 36 hours.  Andrea could bring gusty winds and rain showers to Bermuda on Wednesday.