Tropical Cyclone Winston Gets Stronger and Turns Back Toward Tonga

Tropical Cyclone Winston intensified into the equivalent of a Major Hurricane on Wednesday before it made a slow turn back toward Tonga and Fiji.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Winston was located at latitude 17.1°N and longitude 171.2°W which put it about 160 miles (255 km) north-northwest of Niue and about 240 miles (390 km) east-northeast of Neiafu, Tonga.  Winston was moving toward the west at 3 m.p.h. (5 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 944 mb.

A very favorable environment of Sea Surface Temperatures near 30°C and little vertical wind shear allowed Tropical Cyclone Winston to intensify quickly into the equivalent of a Major Hurricane on Wednesday.  Winston is a small, symmetrical tropical cyclone.  There is a small, well formed eye at its center.  The eye is surrounding by a ring of strong thunderstorms and there are several spiral bands rotating outside the eyewall.  Hurricane force winds extend out about 40 miles (65 km) from the center and tropical storm force winds extend out about 140 miles (225 km) from the center.

Tropical Cyclone Winston could remain in a favorable environment for another 12 to 24 hours.  It has the potential to intensify further during that time.  After that time vertical wind shear could start to increase.  Since the circulation of Winston is relatively small, fluctuations in intensity could occur more quickly.

A subtropical ridge south of Winston turned the tropical cyclone back toward the west on Wednesday.  The ridge is expected to steer Winston slowly westward on Thursday.  The subtropical ridge will steer it toward the west-southwest at a faster speed on Friday.  On its anticipated track Tropical Cyclone Winston could approach the northern islands of Tonga in about 36 hours.  It could be a very strong tropical cyclone at that time and Winston could bring strong winds and heavy rain to those islands.  Winston could be approaching Fiji in about three days.

Tropical Cyclone Winston Intensifies Rapidly East of Tonga

Tropical Cyclone Winston intensified rapidly on Tuesday as it moved east of Tonga.  At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Winston was located at latitude 17.5°N and longitude 171.5°W which put it about 165 miles (270 km) northwest of Niue.  Winston was moving toward the east at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 956 mb.

The upper level winds that were blowing over the top of Tropical Cyclone Winston diminished on Tuesday.  The decrease in vertical wind shear allowed Winston to intensify rapidly and it is now the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.  Tropical Cyclone Winston remains in a favorable environment.  It is over water where the Sea Surface Temperature is near 30°C.  Winston has a well formed eye surrounded by an eyewall containing strong thunderstorms.  Multiple spiral bands are rotating around the core of the circulation.  Winston should continue to intensify and it could intensify rapidly on Wednesday.

A subtropical ridge to the northeast of Winston is slowing the eastward motion of the tropical cyclone.  Winston could continue to move a little farther east on Wednesday before the ridge blocks its motion.  The ridge is forecast to strengthen and extend to the west later this week.  As the ridge extends westward it will force Winston to start to move back toward the southwest.  On its anticipated track Tropical Cyclone Winston could move between Niue and Samoa on Wednesday.  Winston could approach Tonga from the northeast as a much stronger tropical cyclone on Friday.

Tropical Cyclone Winston Moving Through Tonga

Tropical Cyclone Winston brought wind and rain as it moved through Tonga on Monday.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Winston was located at latitude 18.9°S and longitude 175.0°W which put it about 405 miles (650 km) east-southeast of Suva, Fiji and about 140 miles (225 km) north of Nuku’ Alofa, Tonga.  Winston was moving toward the east-northeast at 15 m.p.h. (24 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 990 mb.

The structure of Tropical Cyclone Winston improved on Monday.  A primary rainband wrapped much of the way around the eye and a nearly complete eyewall reformed.  Additional bands of thunderstorms formed mainly in the eastern half of the circulation.  Thunderstorms increased the upper level divergence to the northeast of Winston.

The environment remains marginal for intensification.  A subtropical ridge is generating southwesterly winds over the top of Tropical Cyclone Winston.  Those winds are generating moderate vertical wind shear and are inhibiting re-intensification of Winston.  However, the tropical cyclone is moving over water where the Sea Surface Temperatures are near 30°C.  If the upper level winds diminish, then Tropical Cyclone Winston could re-intensify during the next several days.

The subtropical ridge is steering Winston toward the east-northeast and that general motion is expected to continue for another 24 to 48 hours.  On it anticipated track Tropical Cyclone Winston will move through the Vava’u Group of Tonga.  It could bring strong winds and locally heavy rain to those islands.  Winston could be between Samoa and Niue later this week.

Tropical Cyclone Winston Turns Back Toward Fiji

Tropical Cyclone Winston turned northeastward on Sunday and it began to move back toward Fiji.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Winston was located at latitude 22.6°S and longitude 179.9°E which put it about 345 miles (560 km) south-southeast of Suva, Fiji.  Winston was moving toward the northeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 70 m.p.h. (115 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 978 mb.

A subtropical ridge located northwest of Winston generated southwesterly winds over the top of the tropical cyclone.  The southwesterly winds produced moderate vertical wind shear, which caused Winston to weaken on Sunday.  The circulation of Tropical Cyclone Winston remains fairly intact.  A narrow band of thunderstorms is wrapped around the center of circulation and a remnant eyewall persists.  Other bands of thunderstorms are rotating around the eastern side of the cyclone.  Upper level divergence is still pumping mass out from the northeastern side of the circulation.

Tropical Cyclone Winston is currently over water where the Sea Surface Temperature is near 28°C.  As Winston moves northward it will move over warmer water.  It will also move into an area where the upper level winds are not as strong.  Tropical Cyclone Winston could continue to weaken slowly for another 12 to 24 hours.  It may re-intensify in about two or three days.

The subtropical ridge is likely to continue to steer Winston toward the northeast for anther two or three days.  After that time the subtropical ridge may shift position and allow Winston to turn back toward the west.  On its anticipated track Tropical Cyclone Winston could move over the extreme southeastern islands of Fiji on Monday.  It could bring strong winds, heavy rain and large surf to Vatoa, Ono-i-lau, Tuvana-i-colo, and Tuvana-i-ra.  Tropical Cyclone Winston could affect portions of Tonga during the middle of the week.

Tropical Cyclone Winston Turning East

Tropical Cyclone Winston turned eastward on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Winston was located at latitude 25.2°S and longitude 175.3°E which put it about 545 miles (880 km) south-southwest of Suva, Fiji.  Winston was moving toward the east-southeast at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  The minimum surface pressure was 967 mb.

A subtropical ridge located north of Winston generated easterly winds over the top of the tropical cyclone.  The vertical wind shear caused Tropical Cyclone to weaken on Saturday.  Thunderstorms around the western side of the eyewall weakened and the eye became obscured at times as clouds blew over the top of it.  The vertical structure of the circulation is tilted toward the east with height because of the wind shear.  Tropical Cyclone Winston is likely to continue to weaken on Sunday.  However, it is moving over water where Sea Surface Temperature is near 29°C.  If the circulation maintains its integrity for another 48 hours, the wind shear could diminish and Winston could start to intensify again.

The subtropical ridge is steering Tropical Cyclone Winston toward the east.  The ridge is forecast to move toward the north and that will allow Winston to move more toward the northeast.  On its anticipated track Tropical Cyclone Winston could be near the southeastern islands of Fiji in about three days.

Tropical Cyclones Winston and Tatiana Form over SW Pacific

A pair of tropical cyclones named Winston and Tatiana formed over the southwestern Pacific Ocean on Thursday.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Winston was located at latitude 18.4°S and longitude 171.6°E which put it about 445 miles (720 km) west of Suva, Fiji.  Winston was moving toward the south at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 974 mb.

At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Tatiana was located at latitude 17.3°S and longitude 159.0°E which put it about 620 miles (1000 km) northwest of Noumea, New Caledonia.  Tatiana was moving toward the east-southeast at 6 m.p.h. (10 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 982 mb.

Tropical Cyclone Winston is the stronger and more well organized storm.  It has a well developed eye surrounded by a ring of strong thunderstorms.  Winston is in a very favorable environment.  It is moving over water where the Sea Surface Temperatures are near 31°C.  There is an upper level ridge over Winston and so the upper level winds are light and divergence is occurring in all directions.  Winston is likely to continue to intensify rapidly on Friday and it could become the equivalent of a major hurricane.

Tropical Cyclone Tatiana is smaller and not as well organized.  Tatiana is moving over water where the Sea Surface Temperatures are near 30°C.  However the western end of the same upper level ridge that is over Winston is generating brisk northerly winds over the top of Tropical Cyclone Tatiana.  As a result, vertical wind shear is inhibiting upper level divergence to the north of the center of Tatiana and it is also tilting the circulation toward the south with height.  Wind shear is likely to prevent Tatiana from intensifying significantly.

A subtropical ridge is steering both Winston and Tatiana toward the south.  Tropical Cyclone Winston will pass west of Fiji, but it could come close enough to the extreme southeastern islands of Vanuatu to bring wind and rain to some of those islands.  Tropical Cyclone Tatiana is likely to pass west of New Caledonia, but it could bring rain and higher surf to the west coast of that island.

Tropical Cyclone Stan Brings Wind and Rain to Western Australia

Tropical Cyclone Stan brought wind and rain to the coast of Western Australia as it made landfall on Saturday.  At 2:00 p.m. EDT on Saturday the center of Tropical Cyclone Stan was located at latitude 20.0°S and longitude 119.9°E which put it about 22 miles (35 km) east-northeast of Pardoo Station, Australia.  Stan was moving toward the south-southeast at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 977 mb.

The center of Tropical Cyclone Stan made landfall just east of Pardoo Station.  The circulation of Stan is relatively small and tropical storm force winds only extend about 100 miles from the center.  Most of the heavy rain is occurring west of the center of circulation between Pardoo and Port Hedland.

Tropical Cyclone Stan is moving around the western end of a subtropical ridge.  A trough in the middle levels of the atmosphere is west of Stan and it is helping to steer the tropical cyclone toward the southeast.  That general motion is expected to continue during the next 24 hours.  On its anticipated track Tropical Cyclone Stan will move farther inland over Western Australia.  It could pass near Yarrie in a few hours.

Tropical Cyclone Stan will continue to weaken steadily as it moves farther inland.  It could cause localized wind damage.  Stan could also produce locally heavy rain in isolated locations.

Tropical Cyclone Stan Intensifying As It Nears Western Australia

Tropical Cyclone Stan intensified on Friday as it moved closer to the coast of Western Australia.  At 4:00 p.m. EDT on Friday the center of Tropical Cyclone Stan was located near latitude 18.6°N and longitude 118.9°E which put it about 120 miles (195 km) north of Port Hedland, Australia.  Stan was moving toward the east-southeast at 6 m.p.h. (10 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 982 mb.

The circulation of Tropical Cyclone Stan is much more well organized than it was 24 hours ago.  A primary rainband has wrapped about two thirds of the way around a distinct center of circulation.  There are many more thunderstorms in the core of the circulation and the structure is more symmetrical.  Thunderstorms in the core of Tropical Cyclone Stan are beginning to generate more upper level divergence which is pumping out mass in all directions.

The environment surrounding Tropical Cyclone Stan is now more favorable for intensification.  Stan has moved closer to the center of an upper level ridge that is located east of the tropical cyclone.  As a result, the upper level winds are not as strong and there is less vertical wind shear.  Since Tropical Cyclone Stan is over water where the Sea Surface Temperature is near 29°C, the reduced wind shear allowed it to intensify significantly today.  The environment will be favorable for intensification until Tropical Cyclone Stan makes landfall, and it could become the equivalent of a hurricane within 12 hours.  A period of rapid intensification may be possible.

As Tropical Cyclone Stan moved into an area where the easterly winds in the middle and upper levels were not as strong, it jogged eastward on Friday.  Stan is moving around the western end of a subtropical ridge and it is expected to begin to move more toward the southeast during the next 12 to 24 hours.  The eastward jog today also moved the most likely landfall location to the east.  On its anticipated track Tropical Cyclone Stan is expected to make landfall on the coast of Western Australia in 12 to 24 hours.  The highest probability of landfall is between Broome and Port Hedland near Pardoo Station.

Tropical Cyclone Stan will likely be the equivalent of a hurricane when it makes landfall.  It will be capable of causing wind damage.  Stan will also bring locally heavy rain and a chance for flash floods.  Tropical Cyclone Stan could generate a significant storm surge along the coast near where the center makes landfall.

Tropical Cyclone Stan Heading for Western Australia

A tropical low intensified into Tropical Cyclone Stan on Thursday and it is moving toward Western Australia.  At 10:00 p.m. EST on Thursday the center of Tropical Cyclone Stan was located at latitude 17.7°N and longitude 117.8°E which put it about 190 miles (305 km) north-northwest of Port Hedland, Australia.  Stan was moving toward the south-southeast 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 995 mb.

Tropical Cyclone Stan is not particularly well organized.  A primary rainband curves around the western side of the circulation, but there are not many thunderstorms in the eastern half of the cyclone.  Upper level divergence is occurring to the west of the center, but not to the east of the center.

The environment is marginally favorable for further intensification.  Tropical Cyclone Stan is over water where the Sea Surface Temperature is near 29°C.  However, an upper level ridge east of Stan is generating easterly winds over the top of the tropical cyclone.  The resulting vertical wind shear is inhibiting upper level divergence to the east of Stan.  The tropical cyclone is extracting enough energy from the ocean to intensify but the vertical wind shear is slowing the rate of intensification.  Tropical Cyclone Stan is expected to continue to intensify until it makes landfall.

Tropical Cyclone Stan is moving around the western end of a subtropical ridge which is steering it toward the south-southeast.  The south-southeast motion is expected to continue for another 24 to 36 hours.  On its anticipated track Tropical Cyclone Stan will make landfall on the coast of Western Australia near Port Hedland in about 24 hours.

Tropical Cyclone Stan could be near hurricane intensity when it makes landfall.  It will be capable of causing some wind damage.  Stan could also produce locally heavy rain and flooding.  It will also cause some storm surge near where the center makes landfall.

Tropical Cyclone Organizing Northwest of Australia

A tropical cyclone is organizing northwest of Australia and the Australian Bureau of Meteorology has officially designated it as a tropical low.  At 10:00 p.m. EST on Wednesday the center of the tropical low was located at latitude 15.4°S and longitude 117.7°E which put it about 345 miles (555 km) north of Port Hedland, Australia.  The tropical low was moving toward the south at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1001 mb.

The circulation around the tropical low is still in an organizational phase and there is no well defined center of circulation.  Scattered spiral bands of thunderstorms are beginning to form and rotate around a broad center of circulation.  Much of the convection is still relatively shallow and taller thunderstorms are just beginning to form.  Some upper level divergence is beginning to occur to the west of the tropical low.

The environment is favorable for intensification.  The tropical low is over water where the Sea Surface Temperature is near 30°C.  An upper level ridge east of the tropical low is generating some easterly winds over the system, but the vertical wind shear is probably not strong enough to prevent intensification.  After more thunderstorms consolidate around a center of circulation and the organization of the tropical low improves, intensification is likely.

A subtropical ridge east of the tropical low is steering the low toward the south and that general motion is expected to continue for the next several days.  On its anticipated track, the tropical low could make landfall somewhere along the coast of Western Australia between Broome and Mardie on Friday.  The highest probability is currently for a landfall near Port Hedland in about 48 hours.  However, uncertainty exists about the future track because the tropical low is still organizing and a well defined center of circulation does not yet exist.

The tropical low is likely to bring strong winds, locally heavy rain and some storm surge to parts of the coast of Western Australia.