Tag Archives: SH04

Tropical Cyclone Sarai Moves Across Southern Fiji

Tropical Cyclone Sarai moved across southern parts of Fiji on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Sarai was located at latitude 19.9°S and longitude 179.1°E which put it about 30 miles (50 km) southwest of Matuku, Fiji.  Sarai was moving toward the east at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 976 mb.

Tropical Cyclone Sarai strengthened into the equivalent of a hurricane/typhoon on Saturday as it moved across the southern part of Fiji.  The center of Sarai passed south of Kadavu, but raindbands on the northern side of the circulation brought gusty winds and heavy rain to the island.  A ragged eye appeared intermittently on satellite images.  The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms.  Tropical Cyclone Sarai had a large circulation.  Winds to hurricane/typhoon force extended out 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extended out 200 miles (320 km) from the center.

Tropical Cyclone Sarai will move into an environment that will become increasingly unfavorable for intensification.  Sarai will move over water where the Sea Surface Temperature is near 28°C.  So, there will be enough energy in the upper ocean to support a strong tropical cyclone.  Tropical Cyclone Sarai will move south of an upper level ridge.  The ridge will produce westerly winds which will get stronger during the next several days.  Those winds will cause moderate vertical wind shear.  When the shear gets stronger, Tropical Cyclone Sarai will start to weaken.

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 48 hours.  On its anticipated track Tropical Cyclone Sarai will move across Matuku, Fiji during the next few hours.  Sarai will reach the Lau Group of Fiji Islands during the next 24 hours.  Tropical Cyclone Sarai could reach parts of Tonga within 48 hours.  Sarai will bring gusty winds and heavy rain to all of those places during the next 48 hours.

Tropical Cyclone Sarai Brings Wind and Rain to Fiji

Tropical Cyclone Sarai brought wind and rain to Fiji in Friday.  At 4:00 p.m. EST on Friday the center of Tropical Cyclone Sarai was located at latitude 19.3°S and longitude 177.0°E which put it about 100 miles (160 km) west-southwest of Kadavu, Fiji.  Sarai was moving toward the southeast at 12 m.p.h. (19 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 983 mb.

The center of Tropical Cyclone Sarai passed west of Nadi, Fiji on Friday, but rainbands in the eastern side of the circulation produced gusty winds and heavy rain.  A surface weather station in Nadi measured a sustained wind speed of 44 m.p.h. (70 km/h) and wind gusts of 67 m.p.h. (107 km/h).

Tropical Cyclone Sarai continued to intensify on Friday.  The inner end of a rainband wrapped much of the way around the center of circulation.  The rainband had not wrapped entirely around the northwestern part of the center,  A clear area at the center began to appear on satellite images, which could be evidence of formation of an eye.  Storms around the center were generating upper level divergence which was pumping mass away to the east of the tropical cyclone.  The circulation around Tropical Cyclone Sarai was large.  Winds to tropical storm force extended out 200 miles (320 km) from the center of Sarai.

Tropical Cyclone Sarai will move through an environment favorable for intensification for another 24 to 36 hours.  Sarai will move over water where the Sea Surface Temperature is near 28°C.  It will move south of an upper level ridge.  The ridge will produce westerly winds which will blow toward the top of the circulation.  Those winds will cause moderate vertical wind shear.  The wind shear will inhibit intensification, but it will not be strong enough to keep Tropical Cyclone Sarai from strengthening into the equivalent of a hurricane/typhoon.

Tropical Cyclone Sarai will move south of a subtropical high pressure system over the South Pacific Ocean.  The ridge will steer Sarai toward the east.  On its anticipated track the center of Tropical Cyclone Sarai will pass south of Suva, Fiji.  The core of Sarai will pass near Kadavu, Fiji in about 12 to 18 hours.  Tropical Cyclone Sarai will bring gusty winds and locally heavy rain to Kadavu.  Heavy rain could cause flash floods in some locations.

Tropical Cyclone Sarai Forms Northwest of Fiji

Tropical Cyclone Sarai formed northwest of Fiji on Thursday.  At 10:00 a.m. EST on Thursday the center of Tropical Cyclone Sarai was located at latitude 14.9°S and longitude 175.8°E which put it about 220 miles (355 km) north-northwest of Nadi, Fiji.  Sarai was moving toward the south at 14 m.p.h. (22 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 995 mb.

The circulation around a low pressure system northwest of Fiji exhibited greater organization on Thursday and the Fiji Meteorological Service designated the system as Tropical Cyclone Sarai.  The circulation around Tropical Cyclone Sarai was still organizing.  A band of showers and thunderstorms wrapped around the southern and western sides of the center of circulation.  Other bands of showers and thunderstorms were developing and the bands were starting to revolve around the center.  Storms near the center were generating upper level divergence which was pumping mass away from the tropical cyclone.  The circulation around Tropical Cyclone Sarai was large.  Winds to tropical storm force extended out 150 miles (240 km) from the center of circulation.

Tropical Cyclone Sarai will move through an environment favorable for intensification during the next 48 hours.  Sarai will move over water where the Sea Surface Temperature is near 28°C.  It will move under the western end of an upper level ridge.  The ridge will produce northerly winds which will blow toward the top of the circulation.  However, there will be northerly winds at most levels of the troposphere, which means that there will not be a lot of vertical wind shear.  Tropical Cyclone Sarai will intensify during the next 36 to 48 hours and it could strengthen into the equivalent of a hurricane/typhoon.

Tropical Cyclone Sarai will move around the western end of a subtropical high pressure system over the South Pacific Ocean.  The high will steer Sarai toward the south during the next 24 hours.  Tropical Cyclone Sarai will turn more toward the east in a day or so when it rounds the end of the ridge.  On its anticipated track the center of Sarai could approach western Fiji in 24 to 36 hours.

Tropical Low Forms Over Western Australia

A Tropical Low formed over Western Australia on Monday and a Tropical Cyclone Watch was issued for a portion of the coast.  At 2:00 p.m. EST on Monday the center of the Tropical Low was located at latitude 15.9°S and longitude 126.1°E which put it about 135 miles (220 km) west-southwest of Wyndham, Australia.  It was moving toward the southwest a 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 20 m.p.h. (30 km/h) and there were wind gusts to 50 m.p.h. (85 km/h).  The minimum surface pressure was 1005 mb.  The Australia Bureau of Meteorology has issued a Tropical Cyclone Watch for the portion of the coast of Western Australia from Kuri Bay to Wallal Downs including Broome.

The circulation of the Tropical Low is still organizing.  There is a broad low level center of circulation, but there are not many showers and thunderstorms near the center.  There are numerous bands of showers and storms developing in bands on the eastern and western peripheries of the circulation.  The strongest wind gusts are occurring in those storms.  The lack of storms near the center of circulation is keeping the system from generating much upper level divergence.

The core of the Tropical Low is likely to remain over land for another 12-24 hours, which will inhibit the organization of the circulation.  When the center moves off the coast and over the South Indian Ocean, it will move into an environment favorable for intensification.  The Sea Surface Temperature of the water west of the coast of Western Australia is near 30°C.  The Tropical Low is moving north of the axis of a subtropical ridge.  The ridge is producing easterly winds which are blowing toward the top of the circulation, but there is not a lot of vertical wind shear.  The Tropical Low is likely to strengthen when it moves over water and it could intensify rapidly if a more concentrated center of circulation develops.

A subtropical ridge is current steering the Tropical Low toward the southwest, but a general motion toward the west-southwest is expected during the next 24 to 48 hours.  The Tropical Low will reach the western end of the ridge in about two days and then it will turn more toward the south.  On its anticipated track the center of the Tropical Low is expected to move off the coast between Kuri Bay and Derby on Tuesday.  The center is forecast to pass near Cape Leveque and then turn south toward Wallal Downs.

Elsewhere over the South Indian Ocean, Tropical Cyclone Ava continued to swirl near southern Madagascar and stronger Tropical Cyclone Irving was passing well to the south of Diego Garcia.  At 4:00 p.m. EST on Monday the center of Tropical Storm Ava was located at latitude 27.7°S and longitude 46.8°E which put it about 180 miles (295 km) south of Farodofay, Madagascar.  Ava was moving toward the west-southwest at 17 m.p.h. (27 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.

At 4:00 p.m. EST on Monday the center of Tropical Cyclone Irving was centered at latitude 19.6°S and longitude 76.1°E which put it about 875 miles (1415 km) south-southeast of Diego Garcia.  Irving was moving toward the west-southwest at 18 m.p.h. (29 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 960 mb.  Tropical Cyclone Irving was the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.

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.

Tropical Cyclone Carlos Intensifies Southwest of La Reunion

Tropical Cyclone Carlos intensified on Wednesday as it moved farther southwest of La Reunion.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Carlos was located at latitude 23.9°S and longitude 53.4°E which put it about 240 miles (390 km) south-southwest of St. Denis, La Reunion.  Carlos was moving toward the southeast at 9 m.p.h. (15 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 989 mb.

Tropical Cyclone Carlos is more well organized than it has been during any part of its existence.  A ring of thunderstorms wraps nearly completely around a small eye at the center of circulation.  There is only a small break in the eyewall on the northwest side of the eye.  Several other bands of thunderstorms exist in the eastern half of the circulation.  There are far fewer thunderstorms in the western half of the circulation.  The thunderstorms in the eyewall are generating strong upper level divergence which is pumping out mass in all directions.  The well developed upper level divergence allowed the surface pressure to decrease and the winds increased in response to the lower central pressure.

Tropical Cyclone Carlos moved into an area where the upper level winds were not as strong and the vertical wind shear diminished.  Carlos is currently in an area where there is little vertical wind shear.  It is moving over water where the Sea Surface Temperature is near 28°C.  When the shear diminished the tropical cyclone was able to extract and to use the energy from the ocean more efficiently which allowed it to intensify.  Tropical Cyclone Carlos will continue to move through a favorable environment for another 24 to 36 hours.  It still has a chance to intensify into the equivalent of a hurricane/typhoon.  Eventually, when Tropical Cyclone Carlos moves to a higher latitude, it will move into an area of stronger upper level winds.  When that happens increased wind shear and cooler Sea Surface Temperatures will cause Tropical Cyclone Carlos to weaken.

Tropical Cyclone Carlos has reached the western end of a subtropical ridge.  The counterclockwise flow around the ridge is starting to steer Carlos toward the southeast.  A general southeasterly motion is expected to continue during the next several days.  On its anticipated track the core of Tropical Cyclone Carlos with the strongest winds is expected to pass south of La Reunion.

Tropical Cyclone Carlos Passing West of La Reunion

The core of Tropical Cyclone Carlos passed west of La Reunion on Tuesday.  At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Carlos was located at latitude 21.4°S and longitude 53.2°E which put it about 130 miles (210 km) west-southwest of St. Denis, La Reunion.  Carlos was moving toward the southwest at 7 m.p.h. (11 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 1000 mb.

Limited thunderstorm formation and moderate vertical wind shear caused the low level circulation to weaken slightly on Tuesday.  A few more thunderstorms appeared to develop south of the center of circulation during the past few hours.  Additional thunderstorms seemed to be forming in spiral bands outside the core of the circulation.  The thunderstorms forming south of the core were generating upper level divergence which was pumping mass away from center of circulation,  So, after appearing less organized earlier in the day, the circulation of Tropical Cyclone Carlos seemed to be showing signs of greater organization in recent hours.

An upper level ridge east of Carlos is generating northeasterly winds that are blowing toward the top of the tropical cyclone.  Those winds are producing moderate vertical wind shear, which is inhibiting intensification.  However, Tropical Cyclone Carlos is moving over water where the Sea Surface Temperature is near 28°C.  So, there is plenty of energy in the upper ocean to support strengthening.  The upper level winds could diminish during the next 24 hours.  If the vertical wind shear decreases, then Tropical Cyclone Carlos could intensify during the next 24 to 36 hours.

Carlos is moving around the western end of a subtropical ridge which is steering the tropical cyclone toward the southwest.  Tropical Cyclone Carlos is expected to reach the western end of the ridge in 24 to 36 hours and then it will start to move toward the southeast.  On its anticipated track the core of Tropical Cyclone Carlos will move between La Reunion and Madagascar.  Tropical Cyclone Carlos is expected to pass south of La Reunion after it starts to move toward the southeast.

Tropical Cyclone Carlos brought locally heavy rain to portions of Mauritius and La Reunion.  Outer rainbands could bring some additional rain to parts of La Reunion during the next day or two.

Tropical Cyclone Carlos Weakens As It Passes Northwest of Mauritius

Tropical Cyclone Carlos weakened on Monday as it passed northwest of Mauritius.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Carlos was located at latitude 19.3°S and longitude 56.0°E which put it about 100 miles (160 km) northwest of Port Louis, Mauritius.  Carlos was moving toward the southwest at 10 m.p.h. (16 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.

An upper level ridge centered northeast of Carlos generated northerly winds which created moderate vertical wind shear over the top of the tropical cyclone.  The upper level winds sheared the tops off many of the thunderstorms and created an asymmetrical distribution of the convection.  The strongest thunderstorms are currently in a short spiral band located southwest of the center of circulation.  Although there is a well defined low level circulation, the bands in other parts of Tropical Cyclone Carlos contain mostly showers and low clouds.  The thunderstorms in the short spiral band are generating some upper level divergence which is pumping out mass to the south of the tropical cyclone.

Tropical Cyclone Carlos is moving through an environment that is currently unfavorable for intensification.  However, the environment could become more favorable during the next day or two.  Tropical Cyclone Carlos will move over water where the Sea Surface Temperature is near 28°C.  The strength of the upper level winds could diminish during the next 24 to 48 hours.  If the vertical wind shear decreases, Tropical Cyclone Carlos could intensify before it moves over colder water later this week.  There is still a chance that Tropical Cyclone Carlos could reach hurricane intensity during the next day or two.

A subtropical ridge northeast of Carlos is steering the tropical cyclone toward the southwest.  That general motion is expected to continue for another 24 to 36 hours.  When Carlos reaches the southwestern end of the ridge, it is forecast to turn gradually toward the the southeast.  On its anticipated track the center of Tropical Cyclone Carlos is expected to pass northwest of Mauritius and La Reunion.  Tropical Cyclone Carlos brought locally heavy rain to parts of Mauritius.  Carlos could also bring gusty winds and locally heavy rain to parts of La Reunion.

Tropical Cyclone Carlos Stronger As It Meanders North of Mauritius

Tropical Cyclone Carlos strengthened on Sunday as it meandered slowly north of Mauritius.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Carlos was located at latitude 18.0°S and longitude 57.9°E which put it about 160 miles (260 km) north-northeast of Port Louis, Mauritius.  Carlos was moving toward the east-southeast at 3 m.p.h. (5 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 987.

Although Tropical Cyclone Carlos strengthened on Sunday, the circulation is exhibiting some effects of vertical wind shear.  Thunderstorms dissipated north of the center of circulation and the strongest thunderstorms are currently forming south of the center.  A primary band of storms extends southeast of the center of circulation.  A new broken band of showers and thunderstorms is beginning to develop around the northern periphery of the circulation.  The thunderstorms south of the center are generating upper level divergence which is pumping out mass to the southeast of the tropical cyclone.

The environment around Tropical Cyclone Carlos has both favorable and unfavorable factors.  Carlos will be moving over water where the Sea Surface Temperature is near 28°C which means there is sufficient energy in the upper ocean.  However, an upper level ridge east of Tropical Cyclone Carlos is generating northwesterly winds which are blowing across the top of the circulation.  The upper level winds are generating moderate vertical wind shear which is inhibiting the development of thunderstorms northwest of the center.  The wind shear is contributing to the asymmetrical distribution of the storms around the tropical cyclone and it is inhibiting divergence to the west of Carlos.  If the wind shear continues, it will continue to inhibit intensification.  Tropical Cyclone Carlos does have a very well organized low level circulation and it could intensify if the wind shear decreases.

The steering currents around Tropical Cyclone Carlos are weak, which is why it has not moved much during the past 24 hours.  A subtropical ridge east of Carlos is forecast to strengthen and the ridge is likely to steer the tropical cyclone more toward the southwest during the next day or two.  On its anticipated track the center of Tropical Cyclone Carlos could be near Mauritius in about 24 hours.  Carlos could be approaching La Reunion in 36 hours.  Tropical Cyclone Carlos could be the equivalent of a strong tropical storm or a hurricane when it approaches Mauritius and La Reunion.  Carlos could bring gusty winds and locally heavy rain to those locations.

Tropical Cyclone Carlos Strengthens North of Mauritius

Tropical Cyclone Carlos strengthened on Saturday as it moved north of Mauritius and La Reunion.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Carlos was located at latitude 17.5°S and longitude 56.7°E which put it about 190 miles (310 km) north-northwest of Port Louis, Mauritius.  Carlos was moving toward the south at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 995 mb.

The circulation of Tropical Cyclone Carlos was asymmetrical for much of Saturday, but more thunderstorms formed close to the center of circulation during the past few hours.  There is a small circular clear area at the center of circulation which could indicate the formation of an eye.  Strong thunderstorms are building in a circular ring around the clear area.  The strongest winds are occurring in those thunderstorms.  There are additional showers and thunderstorms developing in bands in the eastern half of the circulation.  Few thunderstorms are forming in the western half of the circulation.  The thunderstorms around core of the circulation are generating upper level divergence which is pumping out mass.

Tropical Cyclone Carlos is moving through an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 28.5°C.  The upper level winds are weak and there is little vertical wind shear.  Carlos is likely to strengthen and there could be a period of rapid intensification if the inner core consolidates around and eye.  Tropical Cyclone Carlos is likely to intensify into the equivalent of a hurricane during the next several days.

Carlos is moving around the western end of a subtropical ridge which is steering the tropical cyclone slowly southward.  A general southward motion is expected to continue for another day or two.  After that time the subtropical ridge is expected to strengthen and steer Tropical Cyclone Carlos more toward the southwest.  On its anticipated track the center of Tropical Cyclone Carlos could be approaching Mauritius and La Reunion in 36 to 48 hours.  Even if the center passes northwest of those locations, Tropical Cyclone Carlos could come close enough to bring gusty winds and locally heavy rainfall.