Monthly Archives: February 2017

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 Dineo Makes Landfall in Mozambique

Tropical Cyclone Dineo made landfall on the coast of Mozambique near Massinga on Wednesday.  Dineo intensified prior to landfall.  The maximum sustained wind speed at the time of landfall was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (170 km/h).  Tropical Cyclone Dineo was capable of causing minor wind damage.  It may have produced a storm surge near and to the south of where the center made landfall.  Tropical Cyclone Dineo is producing locally heavy rain as it moves inland over Mozambique.

At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Dineo was located at latitude 23.3°N and longitude 33.6°E which put it about 125 miles (205 km) west-northwest of Inhambane, Mozambique.  Dineo was moving toward the west at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 70 m.p.h.  (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 981.

Even though it has moved inland the structure of Tropical Cyclone Dineo is still very well organized.  The remnants of the eye and the eyewall are still visible on satellite imagery.  There are several rainbands rotating around the core of Tropical Cyclone Dineo.  The strongest winds are occurring in thunderstorms in the bands that are still offshore over the Indian Ocean.  The thunderstorms near the center of Dineo are still generating upper level divergence which is pumping mass away from the core of the tropical cyclone.

Tropical Cyclone Dineo will continue to weaken slowly as it moves farther inland.  The atmospheric environment is favorable for a tropical cyclone.  The upper level winds are weak and there is little vertical wind shear.  However, now that the core of Dineo is inland, it is away from the warm water of the Indian Ocean which fueled the tropical cyclone’s intensification.  So, Tropical Cyclone Dineo will spin down, but at a slower rate than occurs with some landfalling tropical cyclones.

A subtropical ridge is steering Tropical Cyclone Dineo toward the west and that general motion is expected to continue.  On its anticipated track the center of Tropical Cyclone Dineo could pass near Dindiza, Chigubo and Mapai in Mozambique.  Dineo could produce locally heavy rain when it moves over those areas.  Tropical Cyclone Dineo or its remnants could also bring locally heavy rain to parts of northern South Africa, southern Zimbabwe and eastern Botswana.

Tropical Cyclone Dineo Intensifies As It Nears Mozambique

Tropical Cyclone Dineo intensified on Tuesday as it moved closer to Mozambique.  At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Dineo was located at latitude 22.8°S and longitude 37.5°E which put it about 160 miles (260 km) east-northeast of Inhambane, Mozambique.  Dineo was moving toward the west-southwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h).  The minimum surface pressure was 981 mb.

Tropical Cyclone Dineo intensified on Tuesday and it was on the verge of reaching the intensity of a hurricane/typhoon.  A primary rainband wrapped most of the way around a circular eye.  There was a break on the western side of the developing eyewall.  The strongest winds were occurring in thunderstorms in the eyewall.  Several other bands of showers and thunderstorms were rotating around the core of Tropical Cyclone Dineo.  Thunderstorms around the core of Dineo were generating upper level divergence which was transporting mass away from the center of the tropical cyclone.

Tropical Cyclone Dineo will move through a favorable environment until it reaches Mozambique.  Dineo 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 will allow Tropical Cyclone Dineo to continue to intensify during the next 12 to 18 hours.  It will become the equivalent of a hurricane/typhoon on Wednesday.

A subtropical ridge is steering Tropical Cyclone Dineo toward the west-southwest and that general motion is expected to continue for another 12 to 24 hours.  On its anticipated track Tropical Cyclone Dineo is expected to make landfall on the coast of Mozambique north of Inhambane in less than 24 hours.  Tropical Cyclone Dineo will be the equivalent of a hurricane/typhoon when it makes landfall.  Dineo will bring strong winds and locally heavy rain when it moves into Mozambique.  Heavy rain could create the potential for flash floods.  Tropical Cyclone Dineo will also produce a storm surge along the coast.  The highest storm surge will occur south of where the center makes landfall as the clockwise rotation pushes water toward the coast.

Tropical Cyclone Dineo Moves Toward Mozambique

Tropical Cyclone Dineo started to move slowly toward Mozambique on Monday.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Dineo was located at latitude 22.0°S and longitude 38.9°E which put it about 265 miles (430 km) east-northeast of Inhambane, Mozambique.  Dineo was moving toward the west-southwest at 6 m.p.h. (10 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 994 mb.

The circulation of Tropical Cyclone Dineo became more organized on Monday.  A primary rainband wrapped tightly around the eastern side of the center of circulation.  Recent microwave satellite imagery hinted at the formation of an eye at the center of circulation and a broken eyewall around the developing eye.  The strongest winds were occurring in thunderstorms in the primary rainband.  Additional bands of thunderstorms developed in the eastern half of the circulation.  A few thunderstorms formed west of the center, but most of the bands in that part of the circulation consist of low clouds and showers.  There may be some drier air in the western part of the circulation and the drier air may be inhibiting the development of thunderstorms in that region.  The thunderstorms near the center of circulation are generating upper level divergence.

Tropical Cyclone Dineo will be moving through a favorable environment during the next 24 hours.  It will be moving over water where the Sea Surface Temperature is near 30°C.  An upper level ridge centered over southern Africa will produce southwesterly winds that will blow toward the top of the circulation.  Those winds will produce some wind shear and they will limit upper level divergence on the western side of the circulation.  While the wind shear may slow the rate of intensification during the next 24 hours, Tropical Cyclone Dineo should strengthen on Tuesday.  Dineo could intensify into the equivalent of a hurricane/typhoon before it reaches the coast of Mozambique.

Tropical Cyclone Dineo is near the western end of a subtropical ridge which is steering it slowly toward the west-northwest.  That ridge is expected to continue to steer Tropical Cyclone Dineo toward the west-northwest during the next 12 to 24 hours.  Eventually, the ridge is expected to get stronger and extend westward.  When that happens, the ridge could steer Dineo more toward the west.  On its anticipated track Tropical Cyclone Dineo could approach the coast of Mozambique north of Inhambane in 24 to 30 hours.

Tropical Cyclone Dineo could be the equivalent of a hurricane/typhoon when it reaches Mozambique.  It will bring gusty winds and heavy rain to parts of Mozambique.  Dineo could also generate a storm surge at the coast when it makes landfall.

Tropical Cyclone 05S Forms Over Mozambique Channel

A surface circulation organized quickly inside a low pressure system over the Mozambique Channel on Sunday and the system was designated as Tropical Cyclone 05S.  At 7:00 p.m. EST on Sunday the center or Tropical Cyclone 05S was located at latitude 21.6°N and longitude 39.9°E which put it about 540 miles (870 km) northeast of Maputo, Mozambique.  Tropical Cyclone 05S was moving toward the south-southwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1000 mb.

Tropical Cyclone 05S has a tight center of circulation, but the distribution of thunderstorms is asymmetrical.  Multiple bands of thunderstorms developed in the eastern half of the circulation.  The strongest winds are occurring in the bands of thunderstorms.  However, there are mainly showers and a few isolated thunderstorms in the bands in the western half of the circulation.  The thunderstorms in the bands east of the center of circulation are beginning to generate upper level divergence.

Tropical Cyclone 05S will be moving through a favorable environment during the next several days.  It will be moving over water where the Sea Surface Temperature is near 30°C.  Tropical Cyclone 05S is underneath an upper level ridge.  The upper level winds are weak and there is not much vertical wind shear.  There may be some drier air in the western half of the circulation and that is the only inhibiting factor in the environment around Tropical Cyclone 05S.  Given the mostly favorable environment Tropical Cyclone 05S is likely to intensify during the next day or two.  If an inner core becomes fully developed, then a period of rapid intensification may be possible.

Tropical Cyclone 05S is currently in an area of weak steering currents because of its position underneath the upper level ridge.  Some global models are indicating that a track toward the southwest could be possible if the tropical cyclone moves closer to the western portion of the ridge.  On its anticipated track Tropical Cyclone 05S could move in the general direction of Mozambique.

Tropical Cyclone Carlos Intensifies Southwest of La Reunion

Tropical Cyclone Carlos intensified on Wednesday as it moved farther southwest of La Reunion.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone Carlos was located at latitude 23.9°S and longitude 53.4°E which put it about 240 miles (390 km) south-southwest of St. Denis, La Reunion.  Carlos was moving toward the southeast at 9 m.p.h. (15 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 989 mb.

Tropical Cyclone Carlos is more well organized than it has been during any part of its existence.  A ring of thunderstorms wraps nearly completely around a small eye at the center of circulation.  There is only a small break in the eyewall on the northwest side of the eye.  Several other bands of thunderstorms exist in the eastern half of the circulation.  There are far fewer thunderstorms in the western half of the circulation.  The thunderstorms in the eyewall are generating strong upper level divergence which is pumping out mass in all directions.  The well developed upper level divergence allowed the surface pressure to decrease and the winds increased in response to the lower central pressure.

Tropical Cyclone Carlos moved into an area where the upper level winds were not as strong and the vertical wind shear diminished.  Carlos is currently in an area where there is little vertical wind shear.  It is moving over water where the Sea Surface Temperature is near 28°C.  When the shear diminished the tropical cyclone was able to extract and to use the energy from the ocean more efficiently which allowed it to intensify.  Tropical Cyclone Carlos will continue to move through a favorable environment for another 24 to 36 hours.  It still has a chance to intensify into the equivalent of a hurricane/typhoon.  Eventually, when Tropical Cyclone Carlos moves to a higher latitude, it will move into an area of stronger upper level winds.  When that happens increased wind shear and cooler Sea Surface Temperatures will cause Tropical Cyclone Carlos to weaken.

Tropical Cyclone Carlos has reached the western end of a subtropical ridge.  The counterclockwise flow around the ridge is starting to steer Carlos toward the southeast.  A general southeasterly motion is expected to continue during the next several days.  On its anticipated track the core of Tropical Cyclone Carlos with the strongest winds is expected to pass south of La Reunion.

Tropical Cyclone Carlos Passing West of La Reunion

The core of Tropical Cyclone Carlos passed west of La Reunion on Tuesday.  At 10:00 p.m. EST on Tuesday the center of Tropical Cyclone Carlos was located at latitude 21.4°S and longitude 53.2°E which put it about 130 miles (210 km) west-southwest of St. Denis, La Reunion.  Carlos was moving toward the southwest 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 1000 mb.

Limited thunderstorm formation and moderate vertical wind shear caused the low level circulation to weaken slightly on Tuesday.  A few more thunderstorms appeared to develop south of the center of circulation during the past few hours.  Additional thunderstorms seemed to be forming in spiral bands outside the core of the circulation.  The thunderstorms forming south of the core were generating upper level divergence which was pumping mass away from center of circulation,  So, after appearing less organized earlier in the day, the circulation of Tropical Cyclone Carlos seemed to be showing signs of greater organization in recent hours.

An upper level ridge east of Carlos is generating northeasterly winds that are blowing toward the top of the tropical cyclone.  Those winds are producing moderate vertical wind shear, which is inhibiting intensification.  However, Tropical Cyclone Carlos is moving over water where the Sea Surface Temperature is near 28°C.  So, there is plenty of energy in the upper ocean to support strengthening.  The upper level winds could diminish during the next 24 hours.  If the vertical wind shear decreases, then Tropical Cyclone Carlos could intensify during the next 24 to 36 hours.

Carlos is moving around the western end of a subtropical ridge which is steering the tropical cyclone toward the southwest.  Tropical Cyclone Carlos is expected to reach the western end of the ridge in 24 to 36 hours and then it will start to move toward the southeast.  On its anticipated track the core of Tropical Cyclone Carlos will move between La Reunion and Madagascar.  Tropical Cyclone Carlos is expected to pass south of La Reunion after it starts to move toward the southeast.

Tropical Cyclone Carlos brought locally heavy rain to portions of Mauritius and La Reunion.  Outer rainbands could bring some additional rain to parts of La Reunion during the next day or two.

Tropical Cyclone Carlos Weakens As It Passes Northwest of Mauritius

Tropical Cyclone Carlos weakened on Monday as it passed northwest of Mauritius.  At 10:00 p.m. EST on Monday the center of Tropical Cyclone Carlos was located at latitude 19.3°S and longitude 56.0°E which put it about 100 miles (160 km) northwest of Port Louis, Mauritius.  Carlos was moving toward the southwest at 10 m.p.h. (16 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 997 mb.

An upper level ridge centered northeast of Carlos generated northerly winds which created moderate vertical wind shear over the top of the tropical cyclone.  The upper level winds sheared the tops off many of the thunderstorms and created an asymmetrical distribution of the convection.  The strongest thunderstorms are currently in a short spiral band located southwest of the center of circulation.  Although there is a well defined low level circulation, the bands in other parts of Tropical Cyclone Carlos contain mostly showers and low clouds.  The thunderstorms in the short spiral band are generating some upper level divergence which is pumping out mass to the south of the tropical cyclone.

Tropical Cyclone Carlos is moving through an environment that is currently unfavorable for intensification.  However, the environment could become more favorable during the next day or two.  Tropical Cyclone Carlos will move over water where the Sea Surface Temperature is near 28°C.  The strength of the upper level winds could diminish during the next 24 to 48 hours.  If the vertical wind shear decreases, Tropical Cyclone Carlos could intensify before it moves over colder water later this week.  There is still a chance that Tropical Cyclone Carlos could reach hurricane intensity during the next day or two.

A subtropical ridge northeast of Carlos is steering the tropical cyclone toward the southwest.  That general motion is expected to continue for another 24 to 36 hours.  When Carlos reaches the southwestern end of the ridge, it is forecast to turn gradually toward the the southeast.  On its anticipated track the center of Tropical Cyclone Carlos is expected to pass northwest of Mauritius and La Reunion.  Tropical Cyclone Carlos brought locally heavy rain to parts of Mauritius.  Carlos could also bring gusty winds and locally heavy rain to parts of La Reunion.

Tropical Cyclone Carlos Stronger As It Meanders North of Mauritius

Tropical Cyclone Carlos strengthened on Sunday as it meandered slowly north of Mauritius.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Carlos was located at latitude 18.0°S and longitude 57.9°E which put it about 160 miles (260 km) north-northeast of Port Louis, Mauritius.  Carlos was moving toward the east-southeast at 3 m.p.h. (5 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 987.

Although Tropical Cyclone Carlos strengthened on Sunday, the circulation is exhibiting some effects of vertical wind shear.  Thunderstorms dissipated north of the center of circulation and the strongest thunderstorms are currently forming south of the center.  A primary band of storms extends southeast of the center of circulation.  A new broken band of showers and thunderstorms is beginning to develop around the northern periphery of the circulation.  The thunderstorms south of the center are generating upper level divergence which is pumping out mass to the southeast of the tropical cyclone.

The environment around Tropical Cyclone Carlos has both favorable and unfavorable factors.  Carlos will be moving over water where the Sea Surface Temperature is near 28°C which means there is sufficient energy in the upper ocean.  However, an upper level ridge east of Tropical Cyclone Carlos is generating northwesterly winds which are blowing across the top of the circulation.  The upper level winds are generating moderate vertical wind shear which is inhibiting the development of thunderstorms northwest of the center.  The wind shear is contributing to the asymmetrical distribution of the storms around the tropical cyclone and it is inhibiting divergence to the west of Carlos.  If the wind shear continues, it will continue to inhibit intensification.  Tropical Cyclone Carlos does have a very well organized low level circulation and it could intensify if the wind shear decreases.

The steering currents around Tropical Cyclone Carlos are weak, which is why it has not moved much during the past 24 hours.  A subtropical ridge east of Carlos is forecast to strengthen and the ridge is likely to steer the tropical cyclone more toward the southwest during the next day or two.  On its anticipated track the center of Tropical Cyclone Carlos could be near Mauritius in about 24 hours.  Carlos could be approaching La Reunion in 36 hours.  Tropical Cyclone Carlos could be the equivalent of a strong tropical storm or a hurricane when it approaches Mauritius and La Reunion.  Carlos could bring gusty winds and locally heavy rain to those locations.

Tropical Cyclone Carlos Strengthens North of Mauritius

Tropical Cyclone Carlos strengthened on Saturday as it moved north of Mauritius and La Reunion.  At 10:00 p.m. EST on Saturday the center of Tropical Cyclone Carlos was located at latitude 17.5°S and longitude 56.7°E which put it about 190 miles (310 km) north-northwest of Port Louis, Mauritius.  Carlos was moving toward the south at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 995 mb.

The circulation of Tropical Cyclone Carlos was asymmetrical for much of Saturday, but more thunderstorms formed close to the center of circulation during the past few hours.  There is a small circular clear area at the center of circulation which could indicate the formation of an eye.  Strong thunderstorms are building in a circular ring around the clear area.  The strongest winds are occurring in those thunderstorms.  There are additional showers and thunderstorms developing in bands in the eastern half of the circulation.  Few thunderstorms are forming in the western half of the circulation.  The thunderstorms around core of the circulation are generating upper level divergence which is pumping out mass.

Tropical Cyclone Carlos is moving through an environment that is favorable for intensification.  It is moving over water where the Sea Surface Temperature is near 28.5°C.  The upper level winds are weak and there is little vertical wind shear.  Carlos is likely to strengthen and there could be a period of rapid intensification if the inner core consolidates around and eye.  Tropical Cyclone Carlos is likely to intensify into the equivalent of a hurricane during the next several days.

Carlos is moving around the western end of a subtropical ridge which is steering the tropical cyclone slowly southward.  A general southward motion is expected to continue for another day or two.  After that time the subtropical ridge is expected to strengthen and steer Tropical Cyclone Carlos more toward the southwest.  On its anticipated track the center of Tropical Cyclone Carlos could be approaching Mauritius and La Reunion in 36 to 48 hours.  Even if the center passes northwest of those locations, Tropical Cyclone Carlos could come close enough to bring gusty winds and locally heavy rainfall.