Category Archives: Australian Region

Powerful Tropical Cyclone Debbie Makes Landfall in Queensland

Powerful Tropical Cyclone Debbie made landfall in Queensland on Monday night.  At 9:00 p.m. EDT on Monday the center of Tropical Cyclone Debbie was located at latitude 20.2°S and longitude 148.7°E which put it about 30 miles (50 km) east-southeast of Bowen, Australia.  Debbie was moving toward the southwest at 7 m.p.h. (12 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 943 mb.

Tropical Cyclone Debbie intensified rapidly on Monday into the equivalent of a major hurricane.  A symmetrical eye developed at the center of circulation and a ring of strong thunderstorms surrounded the eye.  Bands of thunderstorms were revolving around the core of Tropical Cyclone Debbie.  Winds to hurricane force extend out about 40 miles (65 km) from the center.  Winds to tropical storm force extended out about 140 miles (225 km) from the center.

The Hurricane Intensity Index (HII) for Tropical Cyclone Debbie was 20.6.  The Hurricane Size Index (HSI) was 16.0 and the Hurricane Wind Intensity Size Index (HWISI) was 36.6.  These indices indicate that Tropical Cyclone Debbie was capable of causing regional major damage.

The center of Tropical Cyclone Debbie made landfall on the coast of Queensland between Bowen and Proserpine.  Debbie will bring strong gusty winds to the portions of Queensland in the path of the tropical cyclone.  Tropical Cyclone Debbie will cause a storm surge along the coast near and to the south of where the center makes landfall.  Debbie will also produce heavy rain as it moves inland and flooding could occur in some areas.

Tropical Cyclone Debbie will weaken after the center moves inland.  The core of Debbie will move across the Clarke Range and those mountains will speed the dissipation of the tropical cyclone.

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 Low Forms Northeast of Queensland

A Tropical Low organized quickly northeast of Queensland over the Coral Sea on Thursday.  At 11:00 p.m. EDT on Thursday the center of the Tropical Low was located at latitude 16.1°S and longitude 151.4°E which put it about 370 miles (600 km) northeast of Townsville, Australia.  The Tropical Low as moving toward the south at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1005 mb.

The low level circulation of the Tropical Low organized quickly on Thursday.  Numerous bands of showers and thunderstorms formed and they began to wrap around a center of circulation.  The distribution of showers and thunderstorms was relatively symmetrical, although there are a few more storms in the eastern half of the circulation.  Storms closer to the center started to generate upper level divergence.

The Tropical Low is in an environment that is very favorable for intensification.  The low is over water where the Sea Surface Temperature is near 30°C.  The upper level winds are light and there is very little vertical wind shear.  The Tropical Low is likely to continue to organize quickly in the favorable environment and it will likely become a named tropical cyclone on Friday.  Once thunderstorms consolidate around the center of circulation, a period of rapid intensification may occur.

The Tropical Low is currently being steered to the south and that motion could continue for another 12 to 24 hours.  A strengthening subtropical ridge is forecast to turn the Tropical Low toward the west in about 24 hours.  On its anticipated track the Tropical Low could approach the coast of Queensland in about three days.

Tropical Cyclone Blanche Strengthens Near Coast of Western Australia

Tropical Cyclone Blanche strengthened on Sunday as it moved over the Timor Sea toward the coast of Western Australia.  At 7:00 p.m. EST on Sunday the center of Tropical Cyclone Blanche was located at latitude 14.0°S and longitude 128.2°E which put it about 100 miles (165 km) north of Wyndham, Australia.  Blanche was moving toward the southwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 988 mb.

The inner core of Tropical Cyclone Blanche became more organized on Sunday.  A band of thunderstorms wrapped about two thirds of the way around the southern and western portions of the center.  The band has the appearance of a partial eyewall.  The strongest winds are occurring in the band near the center.  The thunderstorms are generating upper level divergence which is pumping out mass to the west and southeast of the Tropical Cyclone Blanche.  The upper level divergence allowed the surface pressure to decrease and the wind speed to increase.

Tropical Cyclone Blanche will be over the Timor Sea for a few more hours.  It will be in an environment that is favorable for intensification during that time.  Blanche will move over water where the Sea Surface Temperature is near 29°C.  An upper level ridge east of Blanche is producing northerly winds which are blowing toward the tropical cyclone.  The winds are causing moderate vertical wind shear, but the shear was not strong enough to prevent intensification on Sunday.  Tropical Cyclone Blanche could intensify a little more before it makes landfall.

A subtropical ridge is steering Tropical Cyclone Blanche toward the southwest and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Blanche will make landfall on the coast of Western Australia northwest of Wyndham in a few hours.  Blanche will bring gusty winds and some storm surge to the coast.  It will cause locally heavy rain and the potential for flooding as it moves inland.

Tropical Cyclone Blanche Forms Northwest of Darwin

Tropical Cyclone Blanche formed northwest of Darwin, Australia over the Timor Sea late on Saturday.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Blanche was located at latitude 11.9°S and longitude 130.3°E which put it about 55 miles (85 km) northwest of Darwin, Australia.  Blanche was moving toward the southwest at 7 m.p.h. (12 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 993 mb.

An area of low pressure moved north of the Northern Territory over the Arafura Sea during the past few days.  The low exhibited enough organization for the Australian Bureau of Meteorology to designate it as a tropical low.  The center of the low moved across Melville Island and Bathhurst Island earlier today.  More and stronger thunderstorms began to form closer to the center after it moved over the Beagle Gulf and into the Timor Sea.  The increased convection and organization prompted the Australian Bureau of Meteorology to name the system Tropical Cyclone Blanche.

Although the circulation of Tropical Cyclone Blanche became better organized today, it is still somewhat asymmetrical.  Many of the stronger thunderstorms are occurring in a band south and west of the center or circulation.  Bands north and east of the center contain mainly lower clouds and showers.  An upper level ridge to the east of Blanche is producing northerly winds which are blowing toward the top of the tropical cyclone.  The vertical wind shear appears to have increased during recent hours and the upper level divergence to the east of the center has been reduced.  Part of the lower level circulation appears to becoming exposed on the most recent visible satellite images.

Tropical Cyclone Blanche will be moving through an environment that contains both positive and negative factors.  Blanche will move over water where the Sea Surface Temperature is near 29°C.  So, there is sufficient energy in the upper ocean to support intensification.  However, the upper level ridge to the east of Blanche is producing moderate vertical wind shear, which appears to have stalled intensification for now.  If the wind shear remains moderate, then Blanche will not strengthen.  If the wind shear increases, it could blow the upper portion of the circulation away from the lower part and the tropical cyclone would weaken.  On the other hand if the wind shear decreases, then Tropical Cyclone Blanche could intensify a little more.  There is a great deal of uncertainty about the future intensity of Blanche.

Blanche is moving around the northwestern portion of a subtropical ridge, which is steering the tropical cyclone toward the southwest.  This general motion is expected to continue.  On its anticipated track Tropical Cyclone Blanche will move across the Timor Sea and make landfall on the coast of Western Australia between Wyndham and Kalumburu in 24 to 36 hours.  Tropical Cyclone Blanche could bring some gusty winds, but the primary risk will be locally heavy rainfall and the potential for flooding.

Tropical Cyclone Alfred Develops Over Southwest Gulf of Carpentaria

More thunderstorms developed around the center of a tropical low on Sunday and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Alfred.  At 7:00 p.m. EST on Sunday the center of Tropical Cyclone Alfred was located at latitude 15.4°S and longitude 137.2°E which put it about 75 miles (120 km) northeast of Borroloola, Australia.  Alfred was moving toward the south-southeast at 5 m.p.h. (8 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 997 mb.

An area of low pressure organized over the southeastern Gulf of Carpentaria a few days ago.  The Tropical Low moved across the south coast of the Gulf of Carpentaria and then it moved westward over land.  The low turned north about 36 hours ago and it crossed into the southwest Gulf of Carpentaria on Sunday.  More thunderstorms developed closer to the center of circulation after the circulation moved over water.  Downdrafts in those storms transported stronger winds to the surface.  Upper level divergence pumped out mass and the surface pressure decreased.  When the low pressure system strengthened and acquired the necessary characteristics, the Australian Bureau of Meteorology classified it as Tropical Cyclone Alfred.

The low level circulation of Tropical Cyclone Alfred is well organized but the distribution of thunderstorms is very asymmetrical.  There is a well defined center of circulation that is over the extreme southwestern portion of the Gulf of Carpentaria.  However, most of the thunderstorms are developing southwest of the center of circulation.  Those thunderstorms are where the strongest winds are occurring.  There are few thunderstorms in the other portions of the core of the circulation.  There is one band of showers and thunderstorms farther away from the center on the eastern side of the circulation.

Tropical Cyclone Alfred will be moving through an environment that will be marginally favorable intensification.  It will be moving over water where the Sea Surface Temperature is near 31°C.  So, there is plenty of energy to support intensification.  An upper level ridge east of Alfred is producing northerly winds which are blowing over the top of the tropical cyclone.  Those winds are generating moderate wind shear, which is partially responsible for the asymmetrical distribution of thunderstorms.  In addition, the center is close to the coast and some of the circulation is passing over land.  Tropical Cyclone Alfred could intensify a little more before it gets to coast, but a weakening trend may be more likely.

A subtropical ridge is steering Tropical Cyclone Alfred toward the south-southeast and that general motion is expected to continue for another 12 to 24 hours.  On its anticipated track Tropical Cyclone Alfred could reach the coast near the border between the Northern Territory and Queensland in 12 to 18 hours.  Although Tropical Cyclone Alfred will bring some gusty winds, the greater hazard will be locally heavy rainfall.

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.