Tag Archives: SH09

Former Tropical Cyclone Gita Speeds Toward New Zealand

After causing flooding in Samoa, significant damage in Tonga, and passing southeast of Vanuatu and New Caledonia, former Tropical Cyclone Gita sped toward New Zealand on Monday.  At 4:00 p.m. EST on Monday the center of former Tropical Cyclone Gita was located at latitude 36.6°S and longitude 168.1°E, which put it about 575 miles (930 km) northwest of Wellington, New Zealand.  Gita was moving toward the southeast at 32 m.p.h. (52 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 979 mb.

An upper level trough near the east coast of Australia was generating strong northwesterly winds which were blowing across the top of former Tropical Cyclone Gita.  Those winds were causing significant vertical wind shear.  In addition, former Tropical Cyclone Gita has moved over water where the Sea Surface Temperature is near 23°C.  A combination of strong wind shear and colder water caused the structure of former Tropical Cyclone Gita to evolve into a powerful extratropical cyclone.  It has lost its warm core and a cold front appears to have formed.  The low level circulation has elongated in a north to south orientation.  Even though Gita is now an extratropical cyclone, it is still a powerful low pressure system.  The low is producing winds to 65 m.p.h.  (105 km/h).  Winds to tropical storm force extend out about 230 miles (370 km) from the center of circulation.

The upper level trough is steering former Tropical Cyclone Gita quickly toward the southeast.  On its anticipated track the extratropical cyclone will reach the northern end of the South Island of New Zealand in 12 to 18 hours.  It will produce strong gusty winds capable of toppling trees and bringing down power lines.  The extratropical cyclone will also drop locally heavy rain and it could contribute to flash flooding.

Strong Tropical Cyclone Gita Moves Toward New Caledonia

Strong Tropical Cyclone Gita moved toward New Caledonia on Wednesday.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Gita was located at latitude 21.6°S and longitude 173.7°E which put it about 510 miles (825 km) east of Noumea, New Caledonia.  Gita was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 120 m.p.h (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 949 mb.  Tropical Cyclone Gita was the equivalent of a major hurricane.

The structure of Tropical Cyclone Gita is similar to that of an annular hurricane.  There is a large eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring.  The circulation is symmetrical and several rainbands are revolving around the core of the circulation.  Storms in the core are generating strong upper level divergence which is pumping mass away from the tropical cyclone.  Winds to hurricane/typhoon force extend out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extend out about 165 miles (270 km) from the center.

Tropical Cyclone Gita will be moving through an environment that is favorable for strong tropical cyclone for several more days.  Gita will move over water where the Sea Surface Temperature is near 28°C.  Tropical Cyclone Gita is moving under the western end of an upper level ridge and the upper level winds are weak.  There is little vertical wind shear.  Tropical cyclones with a symmetrical annular structure often are able to maintain their intensity and Tropical Cyclone Gita could stay strong or weaken very slowly during the next 24 hours.  Gita will get close to the western end of the upper level ridge in a day or so and stronger upper level winds could cause more vertical wind shear at that time.

The ridge is steering Tropical Cyclone Gita toward the west.  Gita is likely to move more toward the southwest when it approaches the western end of the ridge.  It is likely to reach the western end of the ridge in about 48 hours, and Gita will turn more toward the south at that time.  On its anticipated track Tropical Cyclone Gita is expected to pass south of Vanuatu.  Gita could approach the Iles Loyaute and New Caledonia in about 36 hours.

Powerful Tropical Cyclone Gita Hits Tonga, Threatens Southern Fiji

Powerful Tropical Cyclone Gita hit the most populated islands in Tonga on Monday and moved west to threaten the southernmost islands of Fiji.  Gita brought strong winds and very heavy rain to Tongapatu and Eau on Monday and there were reports of damage from Tonga.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Gita was located at latitude 21.1°S and longitude 178.9°W which put it about 300 miles (480 km) southeast of Suva, Fiji.  Gita was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 140 m.p.h. (220 km/h) and there were wind gusts to 165 m.p.h. (270 km/h).  The minimum surface pressure was 935 mb.  Tropical Cyclone Gita was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.

Gita remains a powerful tropical cyclone.  There is a circular eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring.  A rainband has wrapped most of the way around the core of Tropical Cyclone Gita and there are indications that a second, concentric eyewall is forming.  Other rainbands are revolving around the core of the circulation.  Storms in the core are producing strong upper level divergence which is pumping away mass and is allowing the tropical cyclone to remain very strong.  Winds to hurricane/typhoon force extend out about 60 miles (95 km) from the center of circulation.  Winds to tropical storm force extend out about 200 miles (320 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Gita is 28.3.  The Hurricane Size Index (HSI) is 20.5 and the Hurricane Wind Intensity Size Index (HWISI) is 48.8.  Those indices indicate that Tropical Cyclone Gita is capable of causing significant damage.

Tropical Cyclone Gita will remain in an environment favorable for strong tropical cyclones for another 24 to 36 hours.  Gita will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is not much vertical wind shear.  If a second concentric eyewall forms, then an eyewall replacement cycle could produce a fluctuation in intensity.  Gita could weaken when the inner eyewall dissipates.  The circulation could strengthen again if the outer eyewall remains intact and starts to contract around the center of circulation.

Tropical Cyclone Gita is moving north of a subtropical ridge which is steering the tropical cyclone toward the west.  A general motion toward the west is expected to continue for another 48 to 72 hours.  On its anticipated track Tropical Cyclone Gita could move over the southernmost islands of Fiji on Tuesday.  The strongest part of Gita could affect Vatoa, Ono-i-lau, Tuvana-i-colo and Tuvana-i-ra.  Gita could bring destructive winds, locally heavy rain and storm surges to the southernmost parts of Fiji.  Tropical Cyclone Gita could approach southern Vanuatu and New Caledonia in about three days.

Powerful Tropical Cyclone Gita Threatens Tonga

Powerful Tropical Cyclone Gita posed an increasing threat to Tonga on Sunday night.  At 10:00 p.m. EST the center of Tropical Cyclone Gita was located at latitude 21.7°S and longitude 173.2°W which put it about 120 miles (195 km) east of Nuku’Alofa, Tonga.  Gita was moving toward the west at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (205 km/h).  The minimum surface pressure was 944 mb.  Tropical Cyclone Gita was the equivalent of a major hurricane.

The circulation of Tropical Cyclone Gita is very well organized.  There is a circular eye at the center of circulation.  A ring of strong thunderstorms surrounds the eye and the strongest winds are occurring in that eye.  Bands of showers and thunderstorms are revolving around the core of Tropical Cyclone Gita.  Storms in the core are generating strong upper level divergence which is pumping mass away in all directions.  Winds to hurricane/typhoon force extend out about 50 miles (80 km) from the center of circulation.  Winds to tropical storm force extend out about 165 miles (270 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Gita is 23.6.  The Hurricane Size Index (HSI) is 16.0 and the Hurricane Wind Intensity Size Index (HWISI) is 39.6.  Those indices indicate that Gita will be capable of causing major damage when it moves over Tonga on Monday.

Tropical Cyclone Gita will be moving through an environment favorable for strong tropical cyclones during the next 24 to 48 hours.  Gita will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  The favorable environment could allow Tropical Cyclone Gita to intensify more before it reaches Tonga.

Tropical Cyclone Gita is moving north of a subtropical ridge which is steering the tropical cyclone toward the west.  A general motion toward the west is expected to continue for another two or three days.  On its anticipated track the center of Tropical Cyclone Gita could reach Tonga within 12 hours.  Tropical Cyclone Gita will be capable of causing major wind damage when it reaches Tonga.  Gita will also drop heavy rain and flooding is possible.  Winds blowing the wind toward the coast could also produce significant storm surges in some locations.

Tropical Cyclone Gita Strengthens Near Niue

Tropical Cyclone Gita strengthened on Saturday as it passed just to the east of Niue.  Outer rainbands on the western side of Gita were bringing gusty winds and heavy rain to Niue.  At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Gita was located at latitude 19.2°S and longitude 168.8°W which put it about 85 miles (135 km) east-southeast of Niue.  Gita was moving toward the south at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h).  The minimum surface pressure was 969 mb.  Tropical Cyclone Gita was the equivalent of a hurricane/typhoon.

The circulation of Tropical Cyclone Gita became more symmetrical on Saturday.  Several rainbands wrapped completely around the center of circulation.  A clear area appeared at the center of circulation on visible satellite images, which indicated that an eye was forming.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in the ring.  Storms in the core of the circulation were generating upper level divergence which was pumping mass away from the tropical cyclone.  Other rainbands were revolving around the core of Tropical Cyclone Gita.

Tropical Cyclone Gita will move through an area favorable for intensification during the next 24 to 48 hours.  Gita will move over water where the Sea Surface Temperature is near 30°C.  Tropical Cyclone Gita is moving around the eastern end of an upper level low, but the upper level winds are weak and there is not much vertical wind shear.  There is drier air to the southwest of Gita, but it does not seem to be entering the circulation of the tropical cyclone.  Tropical Cyclone Gita will continue to intensify and it could strengthen rapidly.  Gita could strengthen into the equivalent of a major hurricane.

The upper level low is steering Tropical Cyclone Gita toward the south.  Gita will turn toward the southeast in about 12 to 24 hours.  When Gita reaches the southern side of the upper low, it will move toward the west.  On its anticipated track Tropical Cyclone Gita will pass just to the southeast of Niue.  Gita could approach Tonga in about 36 hours and it could the equivalent of a major hurricane at that time.

Tropical Cyclone Gita Forms Near Samoa

Tropical Cyclone Gita formed near Samoa on Friday.  At 10:00 a.m. EST on Friday the center of Tropical Cyclone Gita was located at latitude 14.8°N and longitude 172.3°E which put it about 155 miles (250 km) west of Pago Pago, Samoa.  Gita was moving toward the east at 18 m.p.h. (29 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 989 mb.

Tropical Cyclone Gita was bringing gusty winds and heavy rain to Samoa.  The strongest rainbands were north and east of the center of circulation.  The bands south of the center consisted primarily of showers and low clouds.  There appeared to be drier air in the southern half of the circulation which was inhibiting the development of taller clouds and stronger storms in that part of Gita.  Thunderstorms in the rainbands north of the center of circulation were generating upper level divergence which was pumping mass away to the east of the tropical cyclone.

Tropical Cyclone Gita will be moving through an environment favorable for intensification.  Gita will move over water where the Sea Surface Temperature is near 30°C.  An upper level low south of Gita is producing easterly winds which are blowing toward the top of the circulation.  Those winds are causing some vertical wind shear, but the shear does not appear to be strong enough to prevent intensification.  The drier air in southern half of the circulation will inhibit intensification.  However, if some of the rainbands north of the center wrap around the southern side of the center, then they could reduce the effects of the drier air.  Tropical Cyclone Gita is likely to intensify into the equivalent of a hurricane/typhoon during the weekend.

The upper low south of Gita is currently steering the tropical cyclone toward the east.  Gita will approach the eastern end of the upper low during the next 24 hours and it will move more toward the south.  Tropical cyclone Gita will turn back toward the west when it moves south of the upper low.  On its anticipated track Tropical Cyclone Gita will continue to bring gusty winds and heavy rain to Samoa for another 12 to 24 hours.  Gita could pass near Niue in 24 to 48 hours and it could move near Tonga in about three days.

Tropical Cyclone Enawo Hits Madagascar

Powerful Tropical Cyclone Enawo made landfall on the coast of northeastern Madagascar near Ambohitralanana on Tuesday.  Tropical Cyclone Enawo was the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale when it made landfall.  At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Enawo was located near latitude 15.5°S and longitude 49.2°E which put it near Mandritsara, Madagascar.  Enawo was moving toward the southwest at 7 m.p.h. (11 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 980 mb.

Even though the center has been over land for more than 12 hours the circulation of Tropical Cyclone Enawo is still very well organized.  The structure is very symmetrical and there are multiple bands of thunderstorms revolving around the center of circulation.  The strongest winds are occurring in the portions of the rainbands that are over the Indian Ocean.  The circulation of Tropical Cyclone Ewano is still very large and winds to tropical storm force extend out about 200 miles (320 km) from the center.  Thunderstorms near the core of the circulation are generating upper level divergence which is pumping out mass in all directions.

The circulation of Tropical Cyclone Enawo will continue to weaken on Wednesday because the center is over land.  However, the atmospheric environment is favorable for a tropical cyclone.  The upper level winds are weak and there is very little vertical wind shear.  The lack of wind shear will cause the circulation of Tropical Cyclone Enawo to spin down more slowly and it is likely to persist for several more days.

Tropical Cyclone Enawo is moving around the western end of a subtropical high pressure system which is steering the tropical cyclone toward the southwest.  Tropical Cyclone Enawo is likely to turn more toward the south on Wednesday as it reaches the western end of the subtropical high.  On its anticipated track Tropical Cyclone Enawo will move over the center of Madagascar and it could pass near Antananarivo in 24 to 36 hours.  Tropical Cyclone Enawo is producing very heavy rainfall and flash flooding is a serious risk in areas of steep terrain.

Powerful Tropical Cyclone Enawo Nears Madagascar

Powerful Tropical Cyclone Enawo neared Madagascar late on Monday.  At 11:00 p.m. EST on Monday the center of Tropical Cyclone Enawo was located at latitude 14.7°S and longitude 51.1°E which put it about 140 miles (225 km) northeast of Mananara, Madagascar.  Enawo was moving toward the west-southwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 145 m.p.h. (230 km/h) and there were wind gusts to 175 m.p.h. (285 km/h).  The minimum surface pressure was 931 mb.

Tropical Cyclone Enawo intensified rapidly on Monday and it is now the equivalent of a Category 4 hurricane on the Saffir-Simpson Scale.  The circulation of Tropical Cyclone Enawo is very well organized.  There is an circular eye with a diameter of 30 miles (50 km) at the center of the circulation.  The eye is surround by a ring of strong thunderstorms and the strongest winds are occurring in the eyewall.  The remainder of the circulation is symmetrical and additional well formed bands of thunderstorms are revolving around the core of the circulation.  Winds to hurricane force extend out about 70 miles (110 km) from the center.  Winds to tropical storm force extend out about 220 miles (350 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Enawo is 29.9.  The Hurricane Size Index (HSI) is 25.0 and the Hurricane Wind Intensity Size Index (HWISI) is 54.9.  The indices indicate that Tropical Cyclone Enawo is capable of causing significant widespread wind damage.  Tropical Cyclone Enawo is as intense as Hurricane Katrina was just before it made landfall in the coast of Mississippi in 2005.  Enawo is a little smaller than Hurricane Katrina was when Katrina was moving across the Gulf of Mexico in 2005.

Tropical Cyclone Enawo is moving through a very favorable environment.  Enawo is moving over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Enawo is likely to maintain its intensity until it reaches the coast of Madagascar in a few hours.  Enawo will weaken after the center moves inland.

A subtropical ridge is steering Tropical Cyclone Enawo a little to the south of due west and that general motion is expected to continue for another 12 to 24 hours.  Tropical Cyclone Enawo will move near the western end of the subtropical ridge in another day or so and it will start to move more toward the south when it nears the end of the ridge.  On its anticipated track Tropical Cyclone Enawo will make landfall on the northeast coast of Madagascar near Ambohitralanana in a few hours.

Tropical Cyclone Enawo is a dangerous storm.  It is capable of causing widespread significant wind damage when it moves over eastern Madagascar.  The strong winds will also drive water toward the coast and Tropical Cyclone Enawo will generate a significant storm surge near where the center makes landfall.  Enawo will produce very heavy rain and significant inland flooding could occur if rainfall exceeds the capacity of rivers and streams.

Tropical Cyclone Enawo Moves Toward Madagascar and Strengthens

Tropical Cyclone Enawo moved toward Madagascar and strengthened on Sunday.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Enawo was located at latitude 14.0°S and longitude 54.1°E which put it about 340 miles (550 km) east-northeast of Mananara, Madagascar.  Enawo was moving toward the west at 7 m.p.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 961 mb.

The circulation of Tropical Cyclone Enawo is very well organized.  A circular eye is at the center of circulation.  The eye is surrounded by a ring of thunderstorms.  Additional bands of showers and thunderstorms are revolving around the core of the circulation.  The circulation is very symmetrical although there are more thunderstorms in the northwestern quadrant of the circulation.  Thunderstorms in the core of the circulation are generating upper level divergence which is pumping mass away from the tropical cyclone.

The size of the circulation of Tropical Cyclone Enawo increased on Sunday.  Winds to hurricane force extend out about 30 miles (50 km) from the center of circulation.  Winds to tropical storm force extend out about 250 miles (400 km) from the center.  The Hurricane Intensity Index (HII) for Tropical Cyclone Enawo is 17.8.  The Hurricane Size Index (HSI) is 17.8 and the Hurricane Wind Intensity Size Index (HWISI) is 35.6.  These indices indicated that Tropical Cyclone Enawo is capable of causing serious wind damage on a regional scale.

Tropical Cyclone Enawo will continue to move through an favorable environment.  It will move over water where the Sea Surface Temperature is near 29°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Enawo will continue to intensify during the next 24 hours and it could become the equivalent of a major hurricane.

A subtropical ridge is steering Tropical Cyclone Enawo toward the west and a general west or west-southwest motion is expected to continue during the next several days.  On its anticipated track Tropical Cyclone Enawo will approach the coast of Madagascar in about 36 hours.  Enawo will be capable of causing serious wind damage.  It will also generate a storm surge along the coast.  Tropical Cyclone Enawo will produce very heavy rain and a potential for flooding over eastern and southern Madagascar.

Tropical Cyclone Enawo Intensifies Into Equivalent of a Hurricane

Tropical Cyclone Enawo intensified into the equivalent of a hurricane/typhoon on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Enawo was located at latitude 13.9°S and longitude 56.3°E which put it about 475 miles (765 km) north of St. Denis, La Reunion.  Enawo was moving toward the south at 2 m.p.h. (3 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 979 mb.

A primary rainband wrapped around the center of circulation and there was evidence of an eye on microwave satellite imagery.  A broken ring of thunderstorms surrounded the eye.  Additional bands of thunderstorms were rotating around the core of the circulation.  Thunderstorms near the center of circulation were generating upper level divergence which was pumping out mass in all directions.  The circulation of Tropical Cyclone Enawo is relatively small and winds to tropical storm force only extended out about 100 miles (160 km) from the center.

Tropical Cyclone Enawo will move through an environment very favorable for intensification during the next several days.  It will move over water where the Sea Surface Temperature is near 30°C.  The upper level winds are weak and there is little vertical wind shear.  Tropical Cyclone Enawo will continue to intensify and it could intensify rapidly for a time.  Tropical Cyclone Enawo is likely to become the equivalent of a major hurricane within 48 hours.

Tropical Cyclone Enawo was in an area where the steering currents were weak and it did not move much on Saturday.  A subtropical ridge east of Enawo is forecast to strengthen and extend westward.  When the ridge strengthens, it is expected to steer Tropical Cyclone Enawo toward the west-southwest.  On its anticipated track Tropical Cyclone Enawo could approach the coast of northeast Madagascar in 48 to 72 hours.  It could be a strong, dangerous tropical cyclone at that time.