Tag Archives: Toamasina

Tropical Cyclone Francisco Redevelops Near East Coast of Madagascar

After moving slowly westward across the Southwest Indian Ocean for the past few days, Tropical Cyclone Francisco redeveloped near the east coast of Madagascar on Thursday.  At 7:00 a.m. EST on Thursday the center of Tropical Cyclone Francisco was located at latitude 17.9°S and longitude 50.7°E which put it about 90 miles (145 km) east of Toamasina, Madagascar.  Francisco was moving toward the west at 6 m.p.h. (9 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 1004 mb.

Strong vertical wind shear weakened Tropical Cyclone Francisco east of Rodrigues last Thursday, but the lower portion of the circulation remained intact.  The lower level circulation drifted slowly westward during the last seven days and it moved across Mauritius and La Reunion earlier the week.  More thunderstorms began to develop around the lower level circulation on Wednesday, when it moved closer to the east coast of Madagascar.  Bands of showers and thunderstorms began to reform.  Storms near the center of circulation started generating upper level divergence which pumped mass away from the tropical cyclone.  The removal of mass allowed the surface pressure to decrease and the wind speeds began to increase.

Tropical Cyclone Francisco has exhibited greater organization in recent hours.  However, the distribution of thunderstorms was asymmetrical.  Many of the stronger thunderstorms were occurring in bands in the western half of the circulation.  Bands in the eastern half of the circulation consisted primarily of showers and lower clouds.  Francisco was moving under the northern part of an upper level ridge.  The ridge was producing easterly winds which were blowing toward the top of the circulation.  Those winds were causing some vertical wind shear and the shear could be responsible for the asymmetrical distribution of thunderstorms.

Tropical Cyclone Francisco will move through an environment favorable for intensification during the next 6 to 12 hours.  Francisco will move over water where the Sea Surface Temperature is near 28°C.  The upper level ridge will still cause vertical wind shear, but the shear will not be strong enough to prevent intensification.  Tropical Cyclone Francisco will weaken when it moves over Madagascar.

Tropical Cyclone Francisco will move north of a high pressure system over the Southwest Indian Ocean.  The high will steer Francisco toward the west.  On its anticipated track Tropical Cyclone Francisco could make landfall on the east coast of Madagascar in about 12 hours.  Francisco will drop locally heavy rain over parts of central Madagascar.  The heavy rain could cause flash floods in some locations,

Tropical Cyclone Ava Drops Heavy Rain on Madagascar

Tropical Cyclone Ava dropped heavy rain over Madagascar on Saturday.  At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Ava was located at latitude 21.4°S and longitude 48.2°E which put it about 70 miles (110 km) north-northwest of Mananjary, Madagascar.  Ava was moving toward the south-southeast at 11 m.p.h. (17 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 994 mb.

Tropical Cyclone Ava weakened into the equivalent of a tropical storm during the day it spent moving over Madagascar.  The strongest winds were occurring in bands of thunderstorms over the water.  The center made landfall on Friday near Toamasina.  The center then passed near Moramanga, Anosibe An’ala, and Marolambo.  There is still a distinct center of circulation and several bands of showers and thunderstorms are revolving around the center.  Some of the storms dropped heavy rain over parts of Madagascar.  There was stronger rising motion in places where the winds blew up the sides of mountains and the rainfall was heavier in those locations.  The potential for flooding exists in places that received heavy rain.

The center of Tropical Cyclone Ava is likely to move back over the water of the South Indian Ocean during the next few hours.  Tropical Cyclone Ava will move into an environment that is favorable for intensification when it moves back over water.  The Sea Surface Temperature of the water east of Madagascar is near 28°C.  Ava is moving under the axis of an upper level ridge and the upper level winds are relatively weak.  So, there is not a lot of vertical wind shear.  Tropical Cyclone Ava is likely to strengthen once the center moves back over water.

Tropical Cyclone Ava is moving around the western end of a subtropical ridge which is steering Ava toward the south-southeast.  The ridge is forecast to steer Tropical Cyclone Ava toward the south for another day or two.  When Tropical Cyclone Ava moves farther to the south in about 48 hours, an upper level trough will cause northwesterly winds, which will start to steer the tropical cyclone toward the east-southeast.  On its anticipated track the center of Tropical Cyclone Ava is expected to move off the coast of Madagascar near Mananjary in a few hours.

Elsewhere over the South Indian Ocean, Tropical Cyclone Irving was strengthening east-southeast of Diego Garcia.  At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Irving was located at latitude 13.3°S and longitude 87.5°E which put it about 1145 miles (1845 km) east-southeast of Diego Garcia.  Irving was moving toward the west-southwest at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 991 mb.

Satellite imagery suggested that Tropical Cyclone Irving could be strengthening rapidly.  A primary rainband was wrapping around the center of circulation.  An eye appeared to be forming at the center of Irving.  Tropical Cyclone Irving will move through an environment favorable for intensification.  Irving is likely to intensify into the equivalent of a hurricane/typhoon while it passes well to the south of Diego Garcia during the next several days.

Strong Tropical Cyclone Ava Makes Landfall in Madagascar

Strong Tropical Cyclone Ava made landfall on the east coast of Madagascar near Toamasina on Friday.  At 10:00 a.m. EDT on Friday the center of Tropical Cyclone Ava was located near 18.0°S and longitude 49.2°E which put it near Toamasina.  Ava was moving toward the west-southwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 959 mb.  Tropical Cyclone Ava was the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.

Tropical Cyclone Ava intensified rapidly during the past 12 hours and it was still intensifying when it made landfall on the coast of Madagascar.  There was a well defined circular eye at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Several bands of showers and thunderstorms were revolving around the core of the circulation.  Thunderstorms in the core of Tropical Cyclone Ava were generating strong upper level divergence which was pumping away mass and allowed the surface pressure to decrease rapidly.  Winds to hurricane/typhoon force extended out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out about 180 miles (290 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Ava was 17.8.  The Hurricane Size Index (HSI) was 17.6 and the Hurricane Wind Intensity Size Index (HWISI) was 35.4.  Those indices indicate that Tropical Cyclone Ava is capable of causing regional serious damage.  The core of Tropical Cyclone Ava passed over Toamasina and there is likely to be serious wind damage in that city.  Heavy rain was falling in parts of eastern Madagascar and floods could occur.  Tropical Cyclone Ava could produce a storm surge of 10 feet (3 meters) south of where the center made landfall, because the strong winds will be blowing the water toward the coast.

Tropical Cyclone Ava will weaken while the center moves over land in eastern Madagascar.  However, the rest of the environment is favorable for a tropical cyclone.  The Sea Surface Temperature off the east coast of Madagascar is near 28°C.  The upper level winds are weak and there is little vertical wind shear.  If the inner core of Tropical Cyclone Ava remains intact, then Ava could intensify again when the center moves back over the South Indian Ocean in a day or so.

Tropical Cyclone Ava is moving around the western end of a subtropical ridge which is steering the tropical cyclone toward the west-southwest.  Ava will start to move toward the south when it reaches the end of the ridge in a few hours.  On its anticipated track Tropical Cyclone Ava is forecast to move just inland of the east coast of Madagascar.  Ava is forecast to move back off the coast in 24 to 36 hours.  Tropical Cyclone Ava is capable of causing serious damage along the central east coast of Madagascar.

Tropical Cyclone Ava Strengthens East of Madagascar

Tropical Cyclone Ava intensified east of Madagascar on Thursday.  At 4:00 p.m. EST on Thursday the center of Tropical Cyclone Ava was located at latitude 17.4°S and longitude 50.8°E which put it about 125 miles (205 km) east-northeast of Toamasina, Madagascar.  Ava was moving toward the west-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 980 mb.

Tropical Cyclone Ava exhibited the classic structure of a tropical cyclone on Thursday.  A clear eye was evident at the center of circulation on microwave satellite imagery.  The eye was surrounded by a nearly complete ring of showers and thunderstorms.  Spiral bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Ava.  Storms in the core of Ava were generating strong upper level divergence which was pumping mass away from the tropical cyclone.  Winds to tropical storm force extended out about 140 miles (225 km) from the center of circulation.

Tropical Cyclone Ava will move through an environment favorable for intensification on Friday.  Ava will move over water where the Sea Surface Temperature is near 28.5°C.  Tropical Cyclone Ava is moving near the western end of an upper level ridge, but the upper level winds are weak and there is not much vertical wind shear.  Warm water and little vertical wind shear will allow Tropical Cyclone Ava to intensify during the next 24 hours.  Ava should strengthen into the equivalent of a hurricane/typhoon on Friday.

Tropical Cyclone Ava is moving around the western end of a subtropical ridge, which has been steering Ava mostly toward the west.  Tropical Cyclone Ava is forecast to move more toward the southwest on Friday as it nears the western end of the ridge.  On its anticipated track the center of Tropical Cyclone Ava will move close to the east coast of Madagascar near Toamasina in 18 to 24 hours.  When Ava reaches the western end of the ridge in about 24 hours, it will start to move more toward the south.

Tropical Cyclone Ava will bring strong winds and locally heavy rain to the east coast of Madagascar.  The winds will be strong enough to do damage and they could generate a storm surge at the coast.  Rain is already falling on parts of eastern Madagascar and more heavy rain will create the potential for floods.