Category Archives: Tropical Cyclones

Information about tropical cyclones

Tropical Storm Maysak (04W) Forms East of Chuuk

An area of thunderstorms, that generated mesoscale vortices during the past several days developed a persistent center of circulation on Friday and was classified as Tropical Storm Maysak (04W).  At 11:00 p.m. EDT on Friday the center of Tropical Storm Maysak was located at latitude 7.6°N and longitude 154.9°E which put it about 200 miles east of Chuuk and about 800 miles east-southeast of Guam.  Maysak was moving toward the west at 12 m.p.h.  The maximum sustained wind speed was 50 m.p.h. and there were gusts to 65 m.p.h.  The minimum surface pressure was 989 mb.

Maysak formed over very warm Sea Surface Temperatures, but moderate upper level easterly winds were causing vertical wind shear and kept shearing the top off the circulation.  When the system moved further west, it moved into an area where the upper level winds were not as strong and a center of circulation develop and persisted.  The organization of the circulation has increased during the past 12 hours and Maysak has been intensifying.  It is expected to take a westerly track which would keep it in an area where the upper level winds should not be too strong.  Steady intensification is expected and rapid intensification is possible.  Maysak could become a typhoon in 24 hours and it could become the equivalent of a major hurricane in three or four days.

A subtropical ridge is steering Maysak toward the west and it is expected to keep steering it in that direction during the next few days.  The projected track takes Maysak very near Chuuk during the next 18 to 24 hours.  In a few days it is projected to pass between Guam and Yap and head in the general direction of the northern Philippines.

 

Tropical Cyclone Nathan Weakening Over Northern Australia

The center of Tropical Cyclone Nathan moved inland between Maningrida and Goulburn Island on the northern coast of Australia on Monday.  At 11:00 p.m. EDT on Monday the center of Tropical Cyclone Nathan was located at latitude 12.2°S and longitude 133.5°E which put it about 30 miles east-northeast of Gunbalanya, about 45 miles south of Goulburn Island and about 210 miles east of Darwin, Australia.  Nathan was moving toward the southwest at 8 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 60 m.p.h.  The minimum surface pressure was 989 mb.

A combination of factors contributed to the weakening of Nathan.  As the center of circulation moved inland, the clockwise flow pulled in drier air from the interior of Australia.  The drier air reduced the number of thunderstorms and decreased the amount of latent energy released in the remaining thunderstorms.  Since the release of latent energy drives the circulation in a tropical cyclone, the wind speed has been decreasing as well.  In addition, northerly winds in the upper levels are creating moderate vertical wind shear over the top of Nathan.  The wind shear is displacing many of the remaining thunderstorms to the south side of the circulation.  The asymmetrical development of thunderstorms has weakened the inner core of the circulation.  As long as the center of circulation remains over land, it is likely to weaken further.

A subtropical ridge to the south of Nathan is expected to steer it in a mainly westerly direction.  The projected track would take the center of Nathan south of Darwin and keep it over land for about another 36 hours.  The circulation could be fairly weak by the time it moves back over water west of Darwin.  The water west of Darwin is warm and so, it is possible that more thunderstorms could develop, if there is a coherent circulation when the system moves back over the water.

Tropical Cyclone Nathan Moving Parallel to the Northern Coast of Australia

The center of Tropical Cyclone Nathan moved across the northeastern portion of Arnhem Land and it has emerged over the Arafura Sea.  At 10:00 p.m. EDT on Sunday the center of Tropical Cyclone Nathan was located at latitude 11.6°S and longitude 134.7°E which put it about 45 miles northeast of Maningrida, about 35 miles north-northwest of Milingimbi and about 280 miles east-northeast of Darwin, Australia.  Nathan was moving toward the west at 5 m.p.h.  The maximum sustained wind speed was 75 m.p.h. and there were gusts to 95 m.p.h.  The minimum surface pressure was 974 mb.

The core of the circulation was relatively intact when the center of Nathan moved back over water and it had an apparent eye on some satellite imagery and radar displays.  The surface temperatures are quite warm in the Arafura Sea and thunderstorms continue to develop around the southern and western sides of the circulation.  Less convection is occurring on the eastern side of Nathan.  It is possible the moving across land and proximity to the coast is allowing some drier air to be entrained into the circulation.  Light westerly winds in the upper levels may also be creating some vertical wind shear.  The intact core and warm water could allow Nathan to intensify somewhat on Monday.

Nathan is being steered toward the west by a subtropical ridge located to its south.  The ridge is expected to continue to steer Nathan in a general westerly direction for another 24 hours.  The projected track would keep the center of circulation over water.  The ridge is expected to weaken a bit in a day or so, which could allow Nathan turn southwestward and make another landfall on the north coast of Australia.  The southwesterly turn could produce a landfall between Maningrida and Croker Island.

Nathan has a relatively small circulation but it is strong enough to cause wind damage and a significant storm surge near where the center makes landfall.  It could also produce locally heavy rainfall and flooding in inland areas.

Tropical Cyclone Nathan Making Landfall in Northern Australia

The center of Tropical Cyclone Nathan is moving inland near Nhulunbuy, Australia.  At 9:00 p.m. EDT on Saturday the center of Tropical Cyclone Nathan was located at latitude 12.6°S and longitude 136.8°E which put it about 25 miles south of Nhulunbuy and about 90 miles north-northeast of Alyangula, Australia.  Nathan was moving toward the northwest at 8 m.p.h.  The maximum wind speed was 75 m.p.h. and there were gusts to 90 m.p.h.  The minimum surface pressure was 979 mb.

The atmospheric environment around Tropical Cyclone Nathan is favorable for intensification.  The upper level winds are light.  The circulation is well organized and there is upper level outflow pumping out mass.  Outflow channels extend to the northwest and southeast.  However, as the center moves over land, the circulation will weaken.  The center is expected to cross the northeastern corner of Arnhem Land and move back over water in a few hours.  The potential for re-intensification will depend on how far away from the coast the center moves.

A subtropical ridge located southwest of Nathan is steering it toward the northwest.  The ridge is expected to continue to steer the tropical cyclone in that direction for another day or so.  After that time Nathan is expected to start moving more toward the west and eventually toward the southwest and make another landfall on the northern coast of Australia,

Nathan is strong enough to cause some wind damage.  It could also produce a significant storm surge near where the center is making landfall.  Locally heavy rainfall could create possible flooding at inland locations.

Tropical Cyclone Nathan Crossing Cape York Peninsula

Tropical Cyclone Nathan made landfall in Queensland and it is now crossing the Cape York Peninsula.  At 11:00 a.m. EDT on Friday the center of Tropical Cyclone Nathan was located at latitude 14.4°N and longitude 142.2°E which put it about 75 miles west-southwest of Coen, about 80 miles north-northeast of Kowanyama and about 530 miles east-southeast of Alyangula, Australia.  Nathan was moving toward the west at 11 m.p.h.  The maximum sustained wind speed was 65 m.p.h. and there were gusts to 80 m.p.h.  The minimum surface pressure was 984 mb.

Nathan has been weakening as it moves across the Cape York Peninsula in Northern Queensland.  However, it is approaching the Gulf of Carpentaria and the center of circulation will soon be back over water.  The circulation is still mostly intact and it has well developed upper level outflow.  The water at the surface of the Gulf of Carpentaria is very warm.  In addition, the upper level winds around Nathan are very light and there is very little vertical wind shear.  So, the environment around Nathan is quite favorable for intensification and it is possible that a period of rapid re-intensification could occur.

A subtropical ridge is expected to steer Nathan in a west-northwesterly direction during the next several days.  The projected track would have Nathan making another landfall in the Northern Territory between Port Roper and Nhulunbuy in 24 to 36 hours.  If Nathan does reintensify it could bring strong winds and a storm surge to the coast.  It will also be capable of producing locally heavy rainfall and flooding in inland locations.

 

Severe Tropical Cyclone Nathan Making Landfall in Queensland

The center of Severe Tropical Cyclone Nathan is very near the coast of Queensland and it is about to make landfall between Cape Flattery and Cape Melville.  At 11:00 a.m. EDT on Thursday the center of Nathan was located at latitude 14.7°S and longitude 145.6°E which put it about 20 miles northeast of Cape Flattery and about 50 miles north-northeast of Cooktown, Australia.  Nathan was moving toward the west at 11 m.p.h.  The maximum sustained wind speed was 105 m.p.h. and there were gusts to 140 m.p.h.  The minimum surface pressure was 953 mb.

A subtropical ridge is steering Nathan westward and this motion is expected to continue.  The center of Nathan will make landfall soon between Cape Flattery and Cape Melville.  It is capable of producing wind damage and a significant storm surge near where the center crosses the coast.  Nathan could also produce locally heavy rainfall and flooding in some locations.  It is possible that the circulation could emerge intact over the Gulf of Carpentaria.  In that case Nathan could re-intensify somewhat and possibly pose a risk to the western side of the Gulf.

Tropical Cyclone Nathan Approaching Queensland Coast

Tropical cyclone Nathan is moving toward the coast of Queensland and it is intensifying.  At 10:00 p.m. EDT on Wednesday the center of Tropical Cyclone Nathan was located at latitude 14.7°S and longitude 147.4°E which put it about 140 miles east of Cape Flattery, about 190 miles east-northeast of Cooktown and about 200 miles east of Cape Melville.  Nathan was moving toward the west at 7 m.p.h.  The maximum sustained wind speed was 95 m.p.h. and there were gusts to 120 m.p.h.  The minimum surface pressure was 959 mb.

Nathan intensified quickly on Wednesday and it is close to being the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.  The core of the circulation is moving over warm Sea Surface Temperatures.  The upper level winds are light and there is very little vertical wind shear.  Nathan is in a favorable environment and it has well developed upper level outflow.  It is expected to increase in intensity until it makes landfall.

A subtropical ridge building northwest of Nathan is expected to steer it west toward the cost of Queensland.  On the projected track, the center will make landfall between Cape Melville and Cooktown in 12 to 18 hours.  Nathan has the potential to bring strong winds near where the center makes landfall.  Even though the circulation is relatively small, it also has the potential to generate a significant storm surge near the location of landfall.  The strength of the circulation also will create the potential for locally heavy rainfall and flooding as the cyclone moves inland.

Tropical Cyclone Nathan Expected to Intensify and Move Toward Northern Queensland

After making a long slow clockwise loop, Tropical Cyclone Nathan is expected to intensify and move toward Northern Queensland.  At 10:00 p.m. EDT on Tuesday the center of Tropical Cyclone Nathan was located at latitude 15.2°S and longitude 149.2°E which put it about 270 miles east of Cooktown, about 260 miles east-northeast of Cairns and about 330 miles northeast of Townsville, Australia.  Nathan was moving toward the west-southwest at 3 m.p.h.  The maximum sustained wind speed was 60 m.p.h. and there were wind gusts to 80 m.p.h.  The minimum surface pressure was 983 mb.

Wind shear had been inhibiting the re-organization of the circulation around Tropical Cyclone Nathan.  However, it has moved into a much more favorable environment and the circulation has consolidated.  Satellite imagery indicates that Nathan now looks like a classical tropical cyclone with an area of thunderstorms at its center and spiral bands rotating around the core.  Nathan is over warm Sea Surface Temperatures and in an area where the upper level winds are light.  So, further intensification is likely and rapid intensification is possible.

The steering currents around Nathan have been weak.  However, a subtropical ridge is expected to build southwest of the tropical cyclone and steer it westward toward northern Queensland.  The projected track would bring the center of Nathan to the coast near Cooktown in about 36 to 48 hours.   Nathan is expected to intensify during that time and it could be a strong tropical cyclone when it makes landfall.  It has the potential to bring strong winds and a significant storm surge when it reaches the coast.  It could also bring locally heavy rain and possibly flooding as the circulation moves inland over northeastern Queensland.

Wind Shear Still Affecting Tropical Storm Bavi

Strong southerly winds in the upper levels are creating vertical wind shear over Tropical Storm Bavi.  At 11:00 p.m. EDT on Sunday the center of Tropical Storm Bavi was located at latitude 13.4°N and longitude 140.7°W which put it about 250 miles west of Guam and about 1070 miles east of the Philippines.  Bavi was moving toward the west at 22 m.p.h.  The maximum sustained wind speed was 45 m.p.h. and there were wind gusts to 55 m.p.h.  The minimum surface pressure was 993 mb.

A strong upper level ridge east of Bavi is generating brisk southerly winds over the top of the circulation.  Those winds are causing most of the thunderstorms to occur north of the center of circulation.  The structure of the cyclone also appears to be tilted toward the north.  The poor organization of the circulation is preventing it from intensifying.  If the upper level winds do not decrease, it will be difficult for Bavi to organize further.

A subtropical ridge to the north of Bavi is steering it toward the west.  This general motion is expected to continue for the next few days.  The projected track would bring Bavi or its remnants near the Philippines in a few days.

Tropical Cyclone Nathan Organizing Slowly East of Queensland

The structure of Tropical Cyclone Nathan improved on Sunday and it intensified slowly.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Nathan was located at latitude 13.9°N and longitude 149.8° which put it about 300 miles east-northeast of Cooktown, about 420 miles north-northeast of Townsville, Australia and about 250 miles north of Willis Island.  Nathan was moving toward the east-southeast at 3 m.p.h.  The maximum sustained wind speed was 65 m.p.h. and there were gusts to 80 m.p.h.  The minimum surface pressure was 984 mb.

Spiral bands of thunderstorms wrapped around the center of circulation and the structure of Nathan looks more well organized.  It is over warm Sea Surface Temperatures and the upper level winds are not too strong.  As a result, Nathan appears to be developing stronger upper level outflow.  The upper level outflow is pumping out mass, which is allowing the pressure to decrease and the wind speed to increase.  The environment around Nathan could support further intensification during the next 48 hours.

A ridge located northeast of Nathan is steering it slowly toward the south and that motion is likely to continue over the short term.  The winds steering the tropical cyclone could weaken in 24 to 48 hours, which could result in a period of little movement.  Later in the week a second ridge is expected to build northwest of Nathan and start to steer it westward which would move it closer to the east coast of Australia.   The projected track could bring Nathan very close to Willis Island in three or four days.