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Tropical Cyclone Mona Turns Back Toward Fiji

Tropical Cyclone Mona turned back toward Fiji on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Mona was located at latitude 14.9°S and longitude 179.2°E which put it about 250 miles (400 km) north of Suva, Fiji.  Mona was moving toward the east-southeast at 16 m.p.h. (26 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 1002 mb.

After being strongly sheared and making a slow clockwise loop on Friday, Tropical Cyclone Mona resumed a course toward Fiji on Saturday.  An upper level trough west of Fiji was producing northwesterly winds which were blowing toward the top of Tropical Cyclone Mona.  Those winds were causing moderate vertical wind shear and they were also causing the distribution of thunderstorms around Mona to be asymmetrical.  The strongest thunderstorms and winds were occurring in bands southeast of the center of circulation.  Bands in the other parts of the circulation consisted primarily of showers and lower clouds.

Tropical Cyclone Mona will move through an environment marginally favorable for intensification during the next 24 hours.  Mona will move over water where the Sea Surface Temperature is near 28°C.  The upper level trough west of Fiji will continue to cause moderate vertical wind shear which will inhibit development.  Tropical Cyclone Mona could strengthen a little bit on Sunday, but it is likely to remain close to its current intensity.

The upper trough will steer Tropical Cyclone Mona toward the south-southeast during the next 12 hours.  The trough is forecast to cutoff and make a transition to an upper low.  The low will steer Mona more toward the south between 12 and 36 hours into the future.  Tropical Cyclone Mona will turn more toward the southwest on Monday.  On its anticipated track the center of Mona will pass near the northeastern end of Vanua Levu in about 12 hours.

Tropical Cyclone Mona will bring wind and rain to Vanua Levu and the eastern islands of Fiji.  Locally heavy rain could cause flash floods in some locations.

Elsewhere, Tropical Cyclone Penny was moving over the Coral Sea back toward Queensland.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Penny was located at latitude 17.2°S and longitude 154.8°E which put it about 605 miles (980 km) east of Cairns.  Penny was moving toward the southwest at 14 m.p.h. (22 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 996 mb.

Tropical Cyclone Mona Stalls North of Fiji

Tropical Cyclone Mona stalled north of Fiji on Friday.  At 4:00 p.m. EST on Friday the center of Tropical Cyclone Mona was located at latitude 13.3°S and longitude 176.3°E which put it about 365 miles (590 km) north-northwest of Suva, Fiji.  Mona was moving toward the north-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 1000 mb.

Northerly winds blowing around the western end of an upper level ridge over the South Pacific Ocean strengthened on Friday.  Those upper level winds blew across the top of Tropical Cyclone Mona and they caused strong vertical wind shear.  The wind shear blew the upper portion of the circulation south of the circulation in the lower and middle levels of Tropical Cyclone Mona.  As a result, Mona was steered by the winds lower in the atmosphere, which caused it to stall.

New thunderstorms were redeveloping near the center of Tropical Cyclone Mona.  However, many of the bands revolving around the center of Mona still consisted primarily of showers and lower clouds.  The strong upper level winds were shearing the tops off of many of the thunderstorms that developed.  The upper level winds were also preventing the storms near the center of circulation from generating upper level divergence.

Tropical Cyclone Mona could intensify if the upper level winds weaken.  Mona will move over water where the Sea Surface Temperature is near 29°C.  The upper level ridge will continue to produce northerly winds, but those winds are forecast to weaken a little during the weekend.  If the upper level winds weaken and the vertical wind shear lessens, the Tropical Cyclone Mona could strengthen.  However, if the stronger upper level winds persist, then Mona could weaken further.

Tropical Cyclone Mona will meander north of Fiji as long as the wind shear prevents the development of a core of taller thunderstorms.  If Mona strengthens as forecast, then the upper level ridge will steer the tropical cyclone toward the south.  On its anticipated track Tropical Cyclone Mona could approach Fiji in about 48 hours.  Some guidance is suggesting the Mona could be the equivalent of a hurricane/typhoon at that time.

Elsewhere over the South Pacific Ocean, Tropical Cyclone Penny was meandering over the Coral Sea.  At 4:00 p.m. EST on Friday the center of Tropical Cyclone Penny was located at latitude 15.9°S and longitude 155.8°E which put it about 670 miles (1080 km) east of Cairns,, Australia.  Penny was moving toward the north at 2 m.p.h. (3 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 993 mb.

Tropical Cyclone Mona Forms North of Fiji

Tropical Cyclone Mona formed north of Fiji on Wednesday.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Mona was located at latitude 11.6°S and longitude 178.1°E which put it about 460 miles (745 km) north of Suva, Fiji.  Mona was moving toward the south-southeast 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 1003 mb.

A distinct low level center of circulation formed within an area of thunderstorms north of Fiji and the Fiji Meteorological Service designated the system as Tropical Cyclone Mona.  The circulation around Tropical Cyclone Mona was still organizing.  There was a small cluster of thunderstorms around the center of circulation.  Bands of showers and thunderstorms were forming and those bands were revolving around the center of circulation.

Tropical Cyclone Mona will move through an environment somewhat favorable for intensification during the next two days.  Mona will move over water where the Sea Surface Temperature is near 29°C.  It will move around the western end of an upper level ridge.  The ridge will produce northerly winds which will cause some vertical wind shear.  The shear will inhibit strengthening, but it will not be strong enough to prevent intensification.  Tropical Cyclone Mona will intensify during the next 36 to 48 hours and it could strengthen into the equivalent of a hurricane/typhoon.

The upper level ridge will steer Tropical Cyclone Mona toward the south-southeast during the next several days.  On its anticipated track Mona could approach Fiji in 36 to 48 hours.  Tropical Cyclone Mona could be the equivalent of a hurricane/typhoon when it nears Fiji.

Elsewhere over the South Pacific Ocean, Tropical Cyclone Penny was reorganizing over the Coral Sea east of Queensland.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Penny was located at latitude 14.2°S and longitude 152.2°E which put it about 470 miles (760 km) east-northeast of Cairns, Australia.  Penny was moving toward the east-southeast at 24 m.p.h. (39 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 987 mb.

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.