Tag Archives: Australia

Strengthening Tropical Cyclone Debbie Nears Queensland

Tropical Cyclone Debbie strengthened on Sunday as it moved nearer to the coast of Queensland.  At 8:00 p.m. EDT on Sunday the center of Tropical Cyclone Debbie was located at latitude 19.1°S and longitude 150.4°E which put it about 155 miles (250 km) east-northeast of Bowen, Australia.  Debbie was moving toward the south-southwest at 5 m.p.h. (7 km/h).  The maximum sustained wind speed was 80 m.p.h. (130 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 972 mb.

The primary rainband finally wrapped entirely around the center of circulation of Tropical Cyclone Debbie on Sunday and an eye formed.  The eye has a diameter of 35 miles (55 km).  A ring of strong thunderstorms surrounds the eye and the strongest winds are occurring in that eyewall.  Additional bands of showers and thunderstorms are revolving around the core of the circulation.  The circulation is symmetrical and well organized.  Thunderstorms around the core of the circulation are producing upper level divergence which is pumping out mass in all directions and the pressure is decreasing.

Tropical Cyclone Debbie will be moving through an environment favorable for intensification until it makes landfall in Australia.  Debbie will move over water where the Sea Surface Temperature is near 29°C.  The winds in the upper levels are weak and there is little vertical wind shear.  Tropical Cyclone Debbie will intensify until it makes landfall.  Since an eye has formed, Tropical Cyclone Debbie could intensify rapidly on Monday.

Tropical Cyclone Debbie is moving around a ridge over Australia.  The ridge steered Debbie toward the south-southwest on Sunday.  Debbie is expected to start to moving more toward the west-southwest on Monday.  On its anticipated track Tropical Cyclone Debbie could reach the coast of Queensland within 24 hours.  The landfall will likely occur between Ayr and Mackay with the highest probability of a landfall near Bowen.

The Hurricane Intensity Index (HII) for Tropical Cyclone Debbie is 11.5.  The Hurricane Size Index (HSI) is 18.3 and the Hurricane Wind Intensity Size Index (HWISI) is 29.8.  Those indices will increase as Tropical Cyclone Debbie strengthens on Monday.  Tropical Cyclone Debbie will bring strong winds, storm surge and locally heavy rainfall to coastal regions of Queensland.

Tropical Cyclone Debbie Moves Toward Queensland and Strengthens

Tropical Cyclone Debbie moved toward Queensland and strengthened on Saturday.  At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Debbie was located at latitude 18.2°S and longitude 151.2°E which put it about 295 miles (475 km) east-northeast of Townsville, Australia.  Debbie was moving toward the west-southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 95 m.p.h. (155 km/h).  The minimum surface pressure was 982 mb.

The circulation of Tropical Cyclone Debbie continued to become better organized on Saturday.  A primary rainband wrapped around the southern and western sides of the center of circulation.  An eyewall appeared to be forming but there were breaks on the east side of the incipient eyewall.  Additional bands of showers and thunderstorms were revolving around the core of the circulation.  The thunderstorms were generating upper level divergence which was pumping mass out in all directions.  The circulation is very symmetrical and winds to tropical storm force extend out about 190 miles (305 km) from the center.

Tropical Cyclone Debbie will be moving through an environment that is very favorable for intensification during the next 24 hours.  Debbie will move 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 Debbie will continue to intensify and it could intensify rapidly once a complete eyewall surrounds the center of circulation.  Tropical Cyclone Debbie will become the equivalent of a hurricane/typhoon on Sunday and it could strengthen into the equivalent of a major hurricane before it reaches the coast of Queensland.

Tropical Cyclone Debbie is moving around the eastern end of a ridge centered over northern Australia.  The ridge is steering Debbie toward the west-southwest and that general motion is expected to continue during the next several days.  On its anticipated track the center of Tropical Cyclone Debbie could approach the coast of Queensland in 36 hours.  Tropical Cyclone Debbie could make landfall between Mackay and Rollingstone.  The greatest probability currently is for a landfall between Bowen and Townsville near Ayr.

Tropical Cyclone Debbie will bring destructive winds, storm surge and heavy rain to the coast of Queensland in about 36 hours.

Tropical Cyclone Debbie Develops East of Queensland

The low level circulation of a tropical low east of Queensland continued to organize on Friday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Debbie early on Saturday.  At 11:00 p.m. EDT on Friday the center of Tropical Cyclone Debbie was located at latitude 17.4°S and longitude 151.9°E which put it about 360 miles (580 km) east-northeast of Townsville, Australia.  Debbie was moving toward the southwest at 6 m.p.h. (9 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 992 mb.

The low level circulation of Tropical Cyclone Debbie continued to consolidate around the center of circulation on Friday.  Numerous bands of thunderstorms were revolving around the center of circulation and an eye-like feature appeared on satellite imagery at various times.  The structure of the circulation was fairly symmetrical, although there were more bands of showers and thunderstorms in the eastern half of Debbie.  Thunderstorms near the core of the circulation were generating upper level divergence, which was pumping out mass in all directions.

Tropical Cyclone Debbie is moving through an environment that is very favorable for intensification.  Debbie is moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are very weak and there is almost no vertical wind shear.  Tropical Cyclone Debbie should continue to intensify and it could intensify very rapidly once a well developed inner core forms around an eye.  Tropical Cyclone Debbie could strengthen into the equivalent of a major hurricane in two or three days.

A subtropical ridge over northern Australia is steering Tropical Cyclone Debbie toward the southwest and a general southwesterly or west-southwesterly motion is expected to continue for the next two or three days.  On its anticipated track Tropical Cyclone Debbie could approach the coast of Queensland near Townsville in about 72 hours.  Debbie could be the equivalent of a major hurricane when it approaches the coast.

Tropical Cyclone Caleb Forms Over South Indian Ocean

Tropical Cyclone Caleb formed over the South Indian Ocean on Thursday.  At 8:00 a.m. EDT on Thursday the center of Tropical Cyclone Caleb was located at latitude 13.0°S and longitude 100.7°E which put it about 255 miles (410 km) east-southeast of Cocos Island.  Caleb was moving toward the south-southeast at 6 m.p.h. (9 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.

Although there is a well defined low level circulation in Tropical Cyclone Caleb, the distribution of thunderstorms is asymmetrical.  The strongest thunderstorms are occurring in the northwestern quadrant of the circulation and they are in the primary rainband.  Those thunderstorms contain the strongest winds.  There are few thunderstorms in the other parts of the circulation, although there are some bands of lower clouds and showers in those regions.  The thunderstorms in the primary rainband are generating upper level divergence which is pumping out mass to the west of Tropical Cyclone Caleb.

Tropical Cyclone Caleb is in an environment that is marginal for intensification.  Caleb is moving over water where the Sea Surface Temperature is near 28°C.  So, there is enough energy in the upper ocean to support intensification.  However, an upper level ridge located southeast of Caleb is producing easterly winds which are blowing across the top of the tropical cyclone.  The easterly winds are generating moderate vertical wind shear and the shear is probably the reason why most of the thunderstorms are occurring in the northwestern quadrant of the circulation.  The moderate shear will inhibit intensification, but some strengthening may be possible if the upper level winds abate.

A ridge to the east of Caleb is steering the tropical cyclone toward the south-southeast and that general motion is expected to continue for another day or two.  Eventually, a second ridge is forecast to strengthen and steer Tropical Caleb back toward the northwest.

Tropical Cyclone 03S Moving West of Australia

A tropical cyclone designated 03S moved farther west of Australia and weakened on Saturday.  Tropical Cyclone 03S moved across northern Australia as a low pressure system last week before move off the coast near Broome.  After the center of the low moved over the South Indian Ocean thunderstorms developed near the core of the system and the Australian Bureau of Meteorology classified it as a tropical low.  The tropical low strengthened into the equivalent of a tropical storm on Friday night, but the Australian Bureau of Meteorology did not give the system a name.

At 7:00 p.m. EST on Saturday the center of Tropical Cyclone 03S was located at latitude 19.5°S and longitude 109.8°E which put it about 335 miles (540 km) northwest of Learmonth, Australia.  Tropical Cyclone 03S was moving toward the west 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 994 mb.

Tropical Cyclone 03S has a well defined low level circulation but the distribution of thunderstorms is asymmetrical.  Most of the stronger thunderstorms are forming in bands west of the center of circulation.  There are also bands in the eastern half of the circulation but they consist primarily of low clouds and rain showers.  Strong easterly winds in the upper levels are shearing the tops off of any thunderstorms that develop in the eastern part of the circulation.  The easterly winds are also inhibiting upper level divergence to the east of the center.

Tropical Cyclone 03S will move into an environment that will be unfavorable for intensification.  Tropical Cyclone 03S is moving over water where the Sea Surface Temperature is near 26°C, but it will move over cooler water during the next several days.  An upper level ridge centered over Australia is generating easterly winds which are blowing across the top of the tropical cyclone.  The easterly winds are causing moderate vertical wind shear and are responsible for the asymmetrical distribution of thunderstorms.  Tropical Cyclone 03S is likely to weaken slowly during the next several days.

A subtropical ridge will continue to steer Tropical Cyclone 03S to the west during the next few days.  On its anticipated track Tropical Cyclone 03S is expected to move farther away from Western Australia as it weakens.

Tropical Low Forms Over Western Australia

An area of low pressure system has been moving across northern Australia during the past few days.  The low remains organized and the Australian Bureau of Meteorology classified the system as a Tropical Low on Wednesday because of the potential for it to develop into a tropical cyclone.  At 10:00 a.m. EST on Wednesday the center of the Tropical Low was located at latitude 15.9°S and longitude 127.0°E which put it about 80 miles (130 km) west-southwest of Wyndham, Australia.  The Tropical Low was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) an there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1002 mb.

There is a well defined cyclonic circulation in the lower levels of the atmosphere, but there are not many thunderstorms in the core of that circulation.  Most of the thunderstorms are developing in bands that are on the periphery of the circulation.  The strongest thunderstorms are forming in bands in the western portion of the circulation as that part of the Tropical Low begins to moves over water.  The strongest winds are also occurring in these thunderstorms that are over water.  The Tropical Low is moving underneath an upper level ridge and the ridge is causing upper level divergence which is pumping out mass.

The core of the Tropical Low is still over Western Australia and moving over land is the primary factor inhibiting intensification of the system.  The atmospheric environment is favorable for intensification.  The upper level ridge is producing light winds over the Tropical Low and there is little vertical wind shear.  The Sea Surface Temperature of the water west of Australia is near 30°C and there will be plenty of energy in the ocean to support strengthening when the core of the circulation moves west of Australia.  Some slow organization of the circulation is possible during the next 12 hours as the core of the Tropical Low moves closer to the coast of Western Australia.  Further intensification is likely during the next several days once the core of the Tropical Low moves over the warm water.  The Tropical Low could strengthen into the first named tropical cyclone of 2017 later this week.

The upper level ridge is producing light easterly winds which are slowly steering the Tropical Low toward the west.  That general motion is expected to continue for another day or so.  Eventually, the Tropical Low is forecast to move on a west-southwesterly track that would paralle, but keep it to the west of the coast of Western Australia during the next several days.

Tropical Cyclone Yvette Turns Toward Western Australia

Tropical Cyclone Yvette turned toward western Australia on Friday.  At 1:00 p.m. EST on Friday the center of Tropical Cyclone Yvette was located near latitude 15.1°S and longitude 117.3°E which put it about 370 miles (600 km) north-northwest of Port Headland, Australia.  Yvette was moving toward the east-southeast at 8 m.p.h. (13 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 992 mb.

An upper level ridge located to the northeast of Yvette is generating strong northeasterly winds which are blowing across the top of the tropical cyclone.  Those winds are creating strong vertical wind shear and for a time the strong upper levels winds sheared the top off of the circulation.  The upper level winds weakened slightly and new thunderstorms developed near the center of Tropical Cyclone Yvette.  The circulation of Yvette is very asymmetrical.  Most of the new thunderstorms are forming west of the center of circulation, although a few storms recently formed east of the center.  The upper level winds are also preventing upper level divergence to the east of Yvette.

Tropical Cyclone Yvette will be moving through an environment that will be only marginally favorable for intensification.  Yvette will move over water where the Sea Surface Temperature is near 29°C.  So, there is enough energy in the upper ocean to support intensification.  However, the strong upper level winds and vertical wind shear will inhibit intensification.  It is possible that the shear could decrease when Yvette moves east and gets closer to the core of the upper level ridge.  If the shear decreases, then some intensification may occur before Yvette reaches western Australia.

A subtropical ridge is steering Tropical Cyclone Yvette toward the east-southeast and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Yvette will reach the coast of Western Australia in about 36 hours.  Landfall will likely occur between Cape Leveque and De Grey.  The highest probability is for a landfall near Bidyadanga.  Tropical Cyclone Yvette will produce locally heavy rain near where the center makes landfall.  Heavy rain could create the potential for flash floods.

Tropical Cyclone Yvette Develops Northwest of Australia

The circulation of a tropical low northwest of Australia continued to organize on Wednesday and the Australian Bureau of Meteorology named the system Tropical Cyclone Yvette.  At 7:00 a.m. EST on Wednesday the center of Tropical Cyclone Yvette was located at latitude 14.2°N and longitude 114.2°E which put it about 515 miles (830 km) northwest of Port Headland, Australia.  Yvette was making a slow clockwise loop and it was basically stationary.  The maximum sustained wind speed was 45 m.p.h. (70 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 991 mb.

The circulation of Tropical Cyclone Yvette is asymmetrical.  It has a well developed low level circulation but most of the thunderstorms are developing southwest of the center.  An upper level ridge over Australia is generating northeasterly winds which are blowing across the top of the circulation.  The moderate vertical wind shear is probably the reason why most of the thunderstorms are southwest of the center of circulation.  The upper level winds are inhibiting divergence to the east of Yvette, but they are enhancing the divergence to the west of the tropical cyclone.

The environmental factors are marginally favorable for intensification.  Tropical Cyclone Yvette will be moving over water where the Sea Surface Temperature is near 30°C.  The upper level winds are forecast to weaken and the vertical wind shear could decrease during the next several day.  As a result, Tropical Cyclone Yvette could slowly strengthen.

Winds at the steering level are currently variable around Yvette and as a result the tropical cyclone has made several clockwise loops.  The upper level ridge over Australia is forecast to extend west and the ridge is expected to steer Tropical Cyclone Yvette toward Western Australia.  On its anticipated track Tropical Cyclone Yvette is expected to approach the coast of Western Australia in three or four days.

Tropical Cyclone Yvette could bring gusty winds and locally heavy rain when it makes landfall.  Yvette could also generate a storm surge near where the center makes landfall.

Tropical Cyclone 16P Forms Over Gulf of Carpentaria

After a quiet period of several weeks in the tropics Tropical Cyclone 16P formed over the Gulf of Carpentaria on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Cyclone 16P was located at latitude 16.4°S and longitude 140.3°E which put it about 75 miles (120 km) east-northeast of Mornington Island and about 115 miles (185 km) southwest of Kowanyama, Australia.  Tropical Cyclone 16P was moving toward the east-southeast at 12 m.p.h. (18 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 996 mb.

An upper level ridge persisted over the Gulf of Carpentaria during the past few days.  The upper level ridge generated upper level divergence which enhanced rising motion and supported the development of thunderstorms.  Eventually, the upper level divergence pumped out enough mass to allow the surface pressure to decrease and the thunderstorms began to consolidate around a low level center.  The system developed enough organization on Tuesday to be classified as a tropical cyclone.

The organization of Tropical Cyclone 16P improved on Tuesday.  Spiral bands of thunderstorms wrapped around a low level center.  Strong thunderstorms near the center of circulation generated upper level divergence, especially to the east of the tropical cyclone.

The environment is favorable for intensification as long as the center of circulation remains over water.  The Sea Surface Temperatures are near 31°C in the southern Gulf of Carpentaria.  An upper level ridge to the east of the tropical cyclone is generating some vertical wind shear, but the ridge is also enhancing upper level divergence.  The primary inhibiting factor is the proximity of the center of circulation to land.  Tropical Cyclone 16P could intensify further during the next 12 hours before it makes landfall.

The upper level ridge is steering Tropical Cyclone 16P toward the southeast coast of the Gulf of Carpentaria.  On its anticipated track Tropical cyclone 16P is expected to make landfall in Queensland near the mouth of the Gilbert River in about 12 hours.  The potential track after landfall is much more uncertain.  Some guidance suggests that the tropical cyclone could move across the Cape York peninsula toward the Coral Sea.  Other guidance suggests that the tropical cyclone could turn back toward the northwest and move back out into the Gulf of Carpentaria.

Although Tropical Cyclone 16P is likely to cause minor wind damage, it could produce locally heavy rainfall and flooding when it moves over northeastern Queensland.

Tropical Cyclone Winston Stalls Between Vanuatu and Fiji

Steering currents weakened on Sunday and Tropical Cyclone Winston stalled about half way between Vanuatu and Fiji.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Winston was located at latitude 18.0°S and longitude 172.5°E which put it about 300 miles (480 km) east of Port Vila, Vanuatu.  Winston was moving toward the west-southwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 135 m.p.h. (215 km/h).  The minimum surface pressure was 952 mb.

Vertical wind shear over Winston decreased on Sunday and the organization of the tropical cyclone improved.  The eye has become more visible on satellite images and thunderstorms surrounding the eye are generating more upper level divergence.  Easterly winds which were blowing over the top of Winston diminished and the upper level divergence is again flowing out in all directions.

Tropical Cyclone Winston is in an environment that favors intensification.  It is over water where the Sea Surface Temperature is near 30°C.  There is not much vertical wind shear and Winston is likely to intensify during the next 24 hours.

Winston has moved into an area that is between two subtropical ridges.  As a result, it is in an area where the steering winds are not very strong.  The forward motion of Winston has slowed and there is some indication that it may be turning southward.  The guidance from numerical models is forecasting a southerly or southeasterly motion during the next 24 to 48 hours.  On its anticipated track Tropical Cyclone Winston is predicted to stay east of Vanuatu.  However, a more westerly track could bring it closer to that country.