Tag Archives: SH04

Tropical Cyclone Alvaro Starts Extratropical Transition

Tropical Cyclone Alvaro started to make a transition to an extratropical cyclone over the Southwest Indian Ocean south of La Reunion on Wednesday. At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Alvaro was located at latitude 26.8°S and longitude 54.9°E which put it about 405 miles (655 km) south of St. Denis, La Reunion. Alvaro was moving toward the southeast at 21 m.p.h. (33 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 998 mb.

Tropical Cyclone Alvaro began a transition to an extratropical cyclone on Wednesday. Alvaro moved over cooler water. In addition, an upper level ridge over the Southwest Indian Ocean produced strong westerly winds that blew toward the top of Alvaro’s circulation. Those winds caused strong vertical wind shear. The combination of cooler water and strong vertical wind shear caused the structure of Tropical Cyclone Alvaro to change. Thunderstorms were occurring in bands in the southeastern part of Alvaro’s circulation. Bands in the other parts of the circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 150 miles (240 km) from the center of Tropical Cyclone Alvaro.

Tropical Cyclone Alvaro will move through an environment unfavorable for a tropical cyclone during the next 24 hours. Alvaro will move over water where the Sea Surface Temperatures are colder than 26°C. It will continue to move under the southern part of an upper level ridge over the Southwest Indian Ocean. The upper level ridge will continue to cause strong vertical wind shear. The colder water and strong vertical wind shear will cause Tropical Cyclone Alvaro to continue its transition to an extratropical cyclone.

The upper level ridge over the Southwest Indian Ocean will steer Tropical Cyclone Alvaro toward the southeast during the next 24 hours. On its anticipated track, Tropical Cyclone Alvaro will pass south of Mauritius on Thursday.

Tropical Cyclone Alvaro Moves East of Madagascar

Tropical Cyclone Alvaro moved east of Madagascar on Tuesday. At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Alvaro was located at latitude 23.1°S and longitude 50.3°E which put it about 150 miles (240 km) east of Farafangana, Madagascar. Alvaro was moving toward the east-southeast at 13 m.p.h. (21 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 999 mb.

Tropical Cyclone Alvaro weakened to the equivalent of a tropical depression before it moved over the Southwest Indian Ocean east of Madagascar on Tuesday. Alvaro began to intensify slowly after it moved back over water. More thunderstorms began to develop in bands revolving around the center of Tropical Cyclone Alvaro. Those thunderstorms generated upper level divergence that pumped mass away to the east of the tropical cyclone. Winds to tropical storm force extended out 75 miles (120 km) from the center of Alvaro’s circulation.

Tropical Cyclone Alvaro will move through an environment somewhat favorable for intensification during the next 24 hours. Alvaro will move over water where the Sea Surface Temperatures are near 27°C. It will move under the southern part of an upper level ridge over the Southwest Indian Ocean. The upper level ridge will produce westerly winds that will blow toward the top of Alvaro’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification, but the shear may not be enough to prevent some intensification. Tropical Cyclone Alvaro could continue to slowly intensify on Wednesday.

The upper level ridge over the Mozambique Channel will steer Tropical Cyclone Alvaro toward the east-southeast during the next 24 hours. On its anticipated track, Tropical Cyclone Alvaro will move farther east of Madagascar. Alvaro will pass south of La Reunion and Mauritius in 36 hours.

Tropical Cyclone Alvaro Brings Wind and Rain to Southern Madagascar

Tropical Cyclone Alvaro brought wind and rain to southern Madagascar on Monday. At 10:00 p.m. EST on Monday the center of Tropical Cyclone Alvaro was located at latitude 21.5°S and longitude 45.3°E which put it about 40 miles (65 km) north of Fianarantsoa, Madagascar. Alvaro was moving toward the east at 12 m.p.h. (19 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 997 mb.

The center of Tropical Cyclone Alvaro made landfall on the coast of southwest Madagascar north of Morombe on Monday. Alvaro was near hurricane/typhoon intensity at the time of landfall. A circular eye was at the center of Alvaro’s circulation at the time of landfall. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation. Tropical Cyclone Alvaro moved eastward across southern Madagascar and the center was north of Fianarantsoa on Sunday night. Heavy rain was falling over parts of southern Madagascar.

Tropical Cyclone Alvaro weakened after it moved over southern Madagascar on Monday, but Alvaro’s circulation continued to exhibit organization. Bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center of Alvaro generated upper level divergence that pumped mass away to the east of the tropical cyclone. Winds to tropical storm force extended out 60 miles (95 km) from the center of Tropical Cyclone Alvaro.

Tropical Cyclone Alvaro will continue to weaken while the center of circulation moves eastward over southern Madagascar. The center of Alvaro’s circulation could move over the southwest Indian Ocean east of Madagascar in 24 hours. Tropical Cyclone Alvaro will move into an environment somewhat favorable for intensification when it moves back over water. Alvaro will move over water where the Sea Surface Temperatures are near 28°C. It will move under the southern part of an upper level ridge over the southwest Indian Ocean. The upper level ridge will produce westerly winds that will blow toward the top of Alvaro’s circulation. Those winds will cause moderate vertical wind shear. The wind shear will inhibit intensification, but the shear may not be enough to prevent some intensification. Tropical Cyclone Alvaro could intensify when the center moves back over water east of Madagascar.

The upper level ridge over the Mozambique Channel will steer Tropical Cyclone Alvaro toward the east-southeast during the next 24 hours. On its anticipated track, Tropical Cyclone Alvaro will continue to move eastward across southern Madagascar. Heavy rain could cause flash floods in some parts of southern Madagascar. Alvaro will move off the coast of southeast Madagascar between Mananjary and Manakara in about 24 hours. Tropical Cyclone Alvaro could pass south of La Reunion and Mauritius later this week.

Tropical Cyclone Alvaro Intensifies to Near Hurricane/Typhoon Force

Tropical Cyclone Alvaro intensified to near hurricane/typhoon force on Monday morning. At 10:00 a.m. EST on Monday the center of Tropical Cyclone Alvaro was located at latitude 21.6°S and longitude 43.2°E which put it about 50 miles (80 km) northwest of Morombe, Madagascar. Alvaro was moving toward the east-southeast at 11 m.p.h. (17 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 989 mb.

Tropical Cyclone Alvaro strengthened to near hurricane/typhoon force as it approached southern Madagascar on Sunday morning. The inner end of a rainband wrapped around the center of Alvaro’s circulation. A circular eye with a diameter of 40 miles (65 km) formed at the center of Tropical Cyclone Alvaro. Bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated upper level divergence that pumped mass away to the east of the tropical cyclone. Winds to tropical storm force extended out 85 miles (135 km) from the center of Tropical Cyclone Alvaro.

Tropical Cyclone Alvaro will move through an environment favorable for intensification during the next few hours. Alvaro will move over water where the Sea Surface Temperatures are near 30°C. It will move under the southern part of an upper level ridge over the Mozambique Channel. The upper level ridge will produce westerly winds that will blow toward the top of Alvaro’s circulation. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification, but the shear will not be enough to prevent intensification. Tropical Cyclone Alvaro could intensify to the equivalent of a hurricane/typhoon during the next few hours hours before it makes landfall in southern Madagascar.

The upper level ridge over the Mozambique Channel will steer Tropical Cyclone Alvaro toward the east-southeast during the next 24 hours. On its anticipated track, Alvaro will make landfall on the coast of southwest Madagascar north of Morombe in a few hours. Tropical Cyclone Alvaro will bring strong winds and locally heavy rain to southern Madagascar. Bands in the eastern side of Alvaro’s circulation were already dropping heavy rain on parts of southern Madagascar. Heavy rain is likely to cause flash floods in some locations. Tropical Cyclone Alvaro could also cause a storm surge of up to seven feet (two meters) along the coast north of Morombe.

Tropical Cyclone Alvaro Forms over the Mozambique Channel

Tropical Cyclone Alvaro formed over the Mozambique Channel on Sunday morning. At 7:00 a.m. EST on Sunday the center of Tropical Cyclone Alvaro was located at latitude 20.5°S and longitude 39.1°E which put it about 380 miles (610 km) west-northwest of Toliara, Madagascar. Alvaro was moving toward the east-southeast at 8 m.p.h. (13 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 1000 mb.

A low pressure system over the Mozambique Channel intensified on Sunday morning and Meteo France la Reunion designated the system as Tropical Cyclone Alvaro. More thunderstorms formed around the center of Alvaro’s circulation. Storms near the center generated upper level divergence that pumped mass away from the tropical cyclone. Thunderstorms were also forming in bands in the eastern side of Tropical Cyclone Alvaro. Bands in the western side of Alvaro’s circulation consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 80 miles (130 km) in the eastern half of Alvaro. The winds in the western side of Tropical Cyclone Alvaro were blowing at less than tropical storm force.

Tropical Cyclone Alvaro will move through an environment favorable for intensification during the next 24 hours. Alvaro will move over water where the Sea Surface Temperatures are near 30°C. It will move under the southern part of an upper level ridge over the Mozambique Channel. The upper level ridge will produce westerly winds that will blow toward the top of Alvaro’s circulation. Those winds will cause some vertical wind shear. The wind shear will inhibit intensification, but the shear will not be enough to prevent intensification. Tropical Cyclone Alvaro will intensify during the next 24 hours.

The upper level ridge over the Mozambique Channel will steer Tropical Cyclone Alvaro toward the east-southeast during the next 24 hours. On its anticipated track, Alvaro will approach the coast of southwest Madagascar near Morombe on Monday. Tropical Cyclone Alvaro will bring strong winds and locally heavy rain to southern Madagascar. Heavy rain is likely to cause flash floods in some locations.

Tropical Cyclone Seth Speeds South

Tropical Cyclone Seth sped toward the south over the Coral Sea east of Australia on Saturday night. At 7:00 p.m. EST on Saturday the center of Tropical Cyclone Seth was located at latitude 25.8°S and longitude 159.0°E which put it about 385 miles (620 km) east-northeast of Brisbane, Australia. Seth was moving toward the south at 25 m.p.h. (41 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 987 mb.

An upper level trough over eastern Australia and an upper level ridge east of the Coral Sea were combining to steer Tropical Cyclone Seth quickly toward the south on Saturday night. The structure of Seth’s circulation was beginning to resemble a subtropical cyclone. The strongest thunderstorms were occurring in bands south of the center of circulation. Bands in the northern half of Tropical Cyclone Seth consisted primarily of showers and lower clouds. The upper level trough and upper level ridge were producing strong northerly winds that were blowing toward the top of Seth’s circulation. Those winds were causing strong vertical wind shear. Drier air was wrapping around the northern side of Tropical Cyclone Seth. The strong vertical wind shear and drier air were causing the asymmetrical distribution of thunderstorms. The distribution of winds around Seth was also asymmetrical. Winds to tropical storm force extended out 205 miles (335 km) in the southern half of Tropical Cyclone Seth. Winds to tropical storm force extended out 90 miles (150 km) in the northern half of Seth’s circulation.

Tropical Cyclone Seth will move through an environment unfavorable for intensification during the next 24 hours. Seth will move over water where the Sea Surface Temperatures are near 26˚C. However, the upper level trough and upper level ridge will continue to cause strong vertical wind shear. Drier air in the northern half of Seth’s circulation will inhibit the formation of thunderstorms. Tropical Cyclone Seth could make a transition to a subtropical cyclone during the next 24 hours. Seth could maintain its intensity during the transition, but it is likely to weaken during the next few days.

The upper level trough will steer Tropical Cyclone Seth quickly toward the south during the next 12 hours. The upper trough could make a transition to a cutoff low during the next day or so. The center of Seth could move under the cutoff low, which would cause Seth to move more slowly. The cutoff low and Tropical Cyclone Seth could drift west toward Australia during the next several days. On its anticipated track Tropical Cyclone Seth could move slowly toward Australia as a subtropical cyclone.

Tropical Cyclone Seth Spins Northeast of Brisbane

Tropical Cyclone Seth was spinning northeast of Brisbane, Australia on Friday night. At 10:00 p.m. EST on Friday the center of Tropical Cyclone Seth was located at latitude 22.6°S and longitude 157.7°E which put it about 465 miles (745 km) northeast of Brisbane, Australia. Seth was moving toward the southeast at 13 m.p.h. (20 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 992 mb.

Tropical Cyclone Seth strengthened on Friday morning, but then it weakened later in the day. An upper level ridge centered northeast of Australia and an upper level trough over eastern Australia were interacting to produce strong northwesterly winds over the Coral Sea on Friday night. Those winds were blowing toward the top of Seth’s circulation and they were causing moderate vertical wind shear. The wind shear was causing an asymmetric distribution of thunderstorms around Tropical Cyclone Seth. The strongest thunderstorms were occurring in bands southeast of the center of Seth. Bands in the northwestern half of the tropical cyclone consisted primarily of showers and lower clouds. Winds to tropical storm force extended out 155 miles (250 km) in the southern half of Tropical Cyclone Seth. Winds to tropical storm force extended out 100 miles (160 km) in the northern half of the circulation.

Tropical Cyclone Seth will move through an environment unfavorable for intensification during the next 24 hours. Seth will move over water where the Sea Surface Temperatures are near 28˚C. However, the upper level trough over eastern Australia and the upper level ridge over the Coral Sea will continue to produce strong northwesterly winds. Those winds will continue to cause strong vertical wind shear. The wind shear is likely to prevent Tropical Cyclone Seth from intensifying during the next 24 hours. There is a chance that the upper level winds could weaken in 24 hours, which might allow Seth to strengthen at that time.

The upper level trough and ridge will steer Tropical Cyclone Seth toward the south-southeast during the next 24 hours. The upper level trough could evolve into a cutoff low, which could pull Seth back toward the west during the second half of the weekend. On its anticipated track Tropical Cyclone Seth could be east of Brisbane in 36 hours.

Tropical Cyclone Developing East of Vanuatu

A tropical cyclone was developing east of Vanuatu on Friday night. The large low pressure system contained two smaller circulation. One circulation was already designated at Tropical Cyclone 04P by the Joint Typhoon Warning Center. At 10:00 p.m. EST on Friday the center of Tropical Cyclone 04P was located at latitude 14.9°S and longitude 175.8°E which put it about 220 miles (360 km) north-northwest of Nadi, Fiji. It was moving toward the west-southwest at 17 m.p.h. (28 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.

A second larger circulation designated Invest 91P was located northwest of Tropical Cyclone 04P. At 10:00 p.m. EST on Friday the center of Invest 91P was located at latitude 12.6°S and longitude 170.1°E which put it about 310 miles (500 km) east-northeast of Vanuatu. It was moving toward the east at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1002 mb.

Tropical Cyclone 04P and Invest 91P will rotate around each other during the next several days. The circulation around Invest 91P was larger, but the wind speeds were weaker. Upper level divergence from Invest 91P was creating vertical wind shear over Tropical Cyclone 04P. The shear was inhibiting the intensification of Tropical Cyclone 04P. The two circulations are forecast to eventually merge, but numerical models differ on which circulation will become the dominant center of circulation.

The larger environment around Tropical Cyclone 04P and Invest 91P will be favorable for intensification after the two circulations merge. The merged tropical cyclone will be over water where the Sea Surface Temperature is near 29°C. It will be in a region where the upper level winds are weak and there will be little vertical wind shear. Once Tropical Cyclone 04P and Invest 91P consolidate into a single circulation, then the tropical cyclone will intensify. It could strengthen into the equivalent of a hurricane/typhoon early next week.

Tropical Cyclone 04P and Invest 91P will rotate clockwise around each other during the weekend. The overall circulation containing the two systems is forecast to drift slowly toward the south during the next several days. On its forecast track the developing tropical cyclone will move slowly toward the south between Fiji and Vanuatu.

Weakened Tropical Cyclone Sarai Moves Across Tonga

A weakened Tropical Cyclone Sarai moved across Tonga on Monday.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Sarai was located at latitude 20.6°S and longitude 174.9°W which put it about 30 miles (50 km) northeast of Nuku Alofa, Tonga.  Sarai was moving toward the northeast at 8 m.p.h. (13 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 989 mb.

Tropical Cyclone Sarai moved south of an upper level ridge on Monday.  The upper level ridge produced strong westerly winds which blew across the top of Sarai.  Those winds caused strong vertical wind shear and they blew the tops off of thunderstorms in Tropical Cyclone Sarai.  The circulation in the lower levels of Sarai remained intact, but it consisted of showers and lower clouds.  The wind speed gradually decreased during Monday.

The center of Tropical Cyclone Sarai passed just north of the Tongatapu Group of islands.  Sarai passed over the Ha’apai Group of islands.  Tropical Cyclone Sarai brought winds to tropical storm force and squally weather to parts of Tonga.  Rainfall amounts were relatively light because the wind sheared the tops off of any thunderstorms which started to form.

Tropical Cyclone Sarai will move through an environment unfavorable for intensification.  Sarai will move over water where the Sea Surface Temperature is near 27°C.  The upper level ridge will continue to cause strong vertical winds shear.  The wind shear will make it very difficult for new thunderstorms to form.  Tropical Cyclone Sarai is likely to weaken slowly as the circulation in the lower levels spins down.

Tropical Cyclone Sarai will move south of a subtropical high pressure system over the South Pacific Ocean.  The high will steer Sarai toward the east during the next several days.  On its anticipated track Tropical Cyclone Sarai will move south of the Vava’u Group of Islands during the next 24 hours.  Sarai could reach Niue in less than 30 hours.

Tropical Cyclone Sarai Moves Toward Tonga

Tropical Cyclone Sarai moved toward Tonga on Sunday.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Sarai was located at latitude 20.7°S and longitude 178.3°E which put it about 220 miles (355 km) west of Nuku Alofa, Tonga.  Sarai was moving toward the east-southeast at 4 m.p.h. (6 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 985 mb.

Tropical Cyclone Sarai weakened on Sunday.  An upper level ridge north of Sarai produced strong westerly winds which blew toward the top of the circulation.  Those winds caused strong vertical wind shear which disturbed the circulation around Tropical Cyclone Sarai.  The inner core became less well organized and there was no evidence of an eye on satellite images.  The stronger thunderstorms were occurring in bands in the eastern half of the circulation.  Bands in the western half of the circulation consisted primarily of showers and lower clouds.  The circulation around Tropical Cyclone Sarai was still large.  Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation.

Tropical Cyclone Sarai will continue to move through an environment unfavorable for intensification during the next several days.  Sarai will move over water where the Sea Surface Temperature is near 28°C.  However, the upper level ridge will continue to produce strong westerly winds and vertical wind shear is likely to cause Tropical Cyclone Sarai to weaken further.

Tropical Cyclone Sarai will move south of a subtropical high pressure system over the South Pacific Ocean.  The high pressure system will steer Sarai toward the east during the next several days.  On its anticipated track Tropical Cyclone Sarai will move across Tonga in about 24 hours.  Although Sarai will weaken, it will bring winds to tropical storm force and heavy rain to parts of Tonga.