Monthly Archives: October 2019

Tropical Cyclone Maha Forms Southwest of India

Tropical Cyclone Maha formed over the Arabian Sea southwest of India on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Tropical Cyclone Maha was located at latitude 11.0°N and longitude 73.3°E which put it about 140 miles (225 km) southwest of Mangalore, India.  Maha was moving toward the northwest at 11 m.p.h. (17 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.

More thunderstorms formed near the center of a low pressure over the Arabian Sea west of the southern tip of India on Wednesday and the India Meteorological Department designated the system as Tropical Cyclone Maha.  The circulation around Tropical Cyclone Maha was still organizing on Wednesday.  Bands of showers and thunderstorms were forming and the bands were starting to revolve around the center of Maha.  The strongest thunderstorms were occurring in bands in the western half of the circulation.  Some thunderstorms were also forming in bands in the eastern half of the tropical cyclone, but the proximity to southern India may have been making the air a little drier in that part of Maha.  Winds to tropical storm force extended out about 80 miles (130 km) from the center of circulation.

Tropical Cyclone Maha will move through an environment favorable for intensification during the next few days.  Maha will move over water where the Sea Surface Temperature is near 29°C.  It will move underneath the axis of an upper level ridge running east to west over India and the eastern Arabian Sea.  The upper level winds will be weak and there will not be a lot of vertical wind shear during the next day or two.  Tropical Cyclone Maha will continue to intensify and it is forecast to strengthen into the equivalent of a hurricane/typhoon.  Maha could strengthen more quickly once an inner core with an eye and an eyewall develop.

The middle portion of the upper level ridge will steer Tropical Cyclone Maha toward the northwest during the next 48 hours.  When Maha reaches the northern Arabian Sea a second ridge of high pressure over South Asia will steer the tropical cyclone toward the west.  On its anticipated track Tropical Cyclone Maha will move parallel to the west coast of India.

Elsewhere over the Arabian Sea, Tropical Cyclone Kyarr was weakening rapidly southeast of Oman.  The circulation pulled drier air from the Arabian peninsula into the core of Kyarr and most of the thunderstorms dissipated when the drier air reached them.  At 5:00 p.m. EDT on Wednesday the center of Tropical Cyclone Kyarr was located at latitude 18.3°N and longitude 60.7°E which put it about 190 miles (305 km) southeast of Masirah Island, Oman.  Kyarr was moving toward the southwest 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 987 mb.

Tropical Storm Matmo Makes Landfall in Vietnam

Tropical Storm Matmo made landfall on the southern coast of Vietnam near Quy Nhon on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Tropical Storm Matmo was located at latitude 13.7°N and longitude 108.2°E which put it about 50 miles (80 km) west of Quy Nhon, Vietnam.  Matmo was moving toward the west at 13 m.p.h. (20 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 944 mb.

Tropical Storm Matmo organized quickly as it approached the coast of southern Vietnam on Wednesday.  The inner end of a band of showers and thunderstorms wrapped about 75% around the center of circulation and an eye appeared to be forming.  Thunderstorms near the center of Matmo were generating upper level divergence which was pumping mass away from the tropical storm.  The removal of mass allowed the pressure to decrease which caused the wind speed to increase.  The maximum sustained wind speed at the time when Tropical Storm Matmo made landfall was 60-65 m.p.h. (95-105 km/h).

Tropical Storm Matmo began to weaken after the center moved over land.  The strongest winds were occurring in bands of showers and thunderstorms in the eastern half of Matmo over the South China Sea.  Wind speeds in the parts of the circulation what were over land were less.  Tropical Storm Matmo will continue to move westward during the next several days.  Matmo will drop heavy rain over parts of southern Vietnam, Cambodia, southern Laos, and Thailand.  Heavy rain could cause floods in some locations.

Subtropical Storm Rebekah Forms West of the Azores

Subtropical Storm Rebekah formed west of the Azores on Wednesday afternoon.  At 5:00 p.m. EDY on Wednesday the center of Subtropical Storm Rebekah was located at latitude 38.3°N and longitude 40.7°W which put it about 745 miles (1195 km) west of the Azores.  Rebekah was moving toward the east at 13 m.p.h. (20 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 987 mb.

Subtropical Storm Rebekah formed in a manner very similar to the way Hurricane Pablo developed last week.  A small center of circulation developed in the middle of a much larger, extratropical cyclone.  Thunderstorms developed around the center of the small low pressure system.  Even though the small low was over water where the Sea Surface Temperature is near 22°C, cold air in the upper troposphere generated enough instability to allow the thunderstorms to grow upward.  Bands of showers and thunderstorms developed and began to revolve around the small low pressure system, and the National Hurricane Center designated the system at Subtropical Storm Rebekah.  Winds to tropical storm force extended out 90 miles (145 km) from the center of Rebekah.

Subtropical Storm Rebekah could strengthen during the next 24 hours.  Although Rebekah will move over water where the Sea Surface Temperature is near 22°C, colder air in the middle and upper troposphere will keep enough potential instability in the atmosphere to allow for the continued development of thunderstorms.  Since Rebekah is at the center of the larger low pressure system, the vertical wind shear will be less.  Subtropical storm Rebekah may intensify during the next day or so and it could make a transition to a tropical storm.

Subtropical Storm Rebekah will move eastward along with the larger low pressure system that surrounds the much smaller subtropical storm.  Southerly winds blowing around the eastern side of the larger low could push Rebekah toward the north at times.  On its anticipated track Subtropical Storm Rebekah could approach the western Azores on Friday.

Tropical Cyclone Kyarr Weakens East of Oman

Tropical Cyclone Kyarr weakened east of Oman on Tuesday.  At 11:00 EDT on Tuesday the center of Tropical Cyclone Kyarr was located at latitude 19.5°N and longitude 62.0°E which put it about 220 miles (355 km) east-southeast of Masirah Island, Oman.  Kyarr was moving toward the west at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (230 km/h).  The minimum surface pressure was 954 mb.

The structure of the circulation around Tropical Cyclone Kyarr exhibited less organization on Tuesday.  The southwestern part of the ring of thunderstorms around the eye weakened.  In addition, bands of showers and thunderstorms in the western half of Kyarr also weakened.  Two factors seemed to be contributing to the weakening trend.  Tropical Cyclone Kyarr moved slowly during the last 24 to 36 hours.  The circulation mixed cooler water to the upper levels of the Arabian Sea and Kyarr was not able to extract as much energy from the water.  The circulation around Tropical Cyclone Kyarr may have pulled drier air from the Arabian peninsula into the western half of the circulation.  Even though Kyarr weakened on Tuesday. winds to hurricane/typhoon force extended out 35 miles (55 km) from the center of circulation.  Winds to tropical storm force extended out 130 miles (210 km) from the center.

Tropical Cyclone Kyarr will probably continue to weaken during the next several days.  Kyarr will move away from the cooler water it mixed to the surface and it will be in an area where there will not be a lot of vertical wind shear.  However, Tropical Cyclone Kyarr is likely to draw more drier air into the circulation.  The drier air will make it more difficult for thunderstorms to develop in rainbands around the tropical cyclone.

Tropical Cyclone Kyarr will move south of a ridge of high pressure over southwest Asia.  The high is forecast to strengthen during next several days.  When the high strengthens it will steer Kyarr toward the southwest.  On its anticipated track Tropical Cyclone Kyarr will move parallel to the coast of Oman.  Kyarr could approach Socotra Island and Somalia in four or five days.

Tropical Storm Matmo Forms East of Vietnam

Tropical Storm Matmo formed over the South China Sea east of Vietnam on Tuesday.  At 5:00 p.m. EDT on Tuesday the center of Tropical Storm Matmo was located at latitude 12.7°N and longitude 112.2°E which put it about 60 miles (260 km) east of Dai Lanh, Vietnam.  Matmo was moving toward the west at 16 m.p.h. (26 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 998 mb.

More thunderstorms developed near the center of a low pressure system over the South China Sea east of Vietnam on Tuesday and the Japan Meteorological Agency designated the system as Tropical Storm Matmo.  The circulation around Tropical Storm Matmo was still organizing.  Thunderstorms were forming around the center of circulation.  Bands of showers and thunderstorms were developing in the northern and western parts of the tropical storm.  Bands in the eastern and southern parts of the circulation consisted primarily of showers and lower clouds.  Storms near the center of circulation were beginning to generate upper level divergence.

Tropical Storm Matmo will move through an environment favorable for intensification during the next 12 to 18 hours.  Matmo will move over water where the Sea Surface Temperature is near 29°C.  It will move under the west part of an upper level ridge where the winds are weaker and where there is less vertical wind shear.  Tropical Storm Matmo could strengthen during the next 12 hours.  Matmo will near the coast of Vietnam in about 12 hours and it will start to weaken when the center moves over land.

Tropical Storm Matmo will move south of a ridge of high pressure over the Western North Pacific Ocean.  The ridge will steer Matmo toward the west.  On its anticipated track Tropical Storm Matmo could make landfall on the coast of Vietnam between Dai Lanh and Quy Nhon in 12 to 18 hours.  Matmo will bring gusty winds to the coastal regions of southern Vietnam.  Tropical Storm Matmo could also drop heavy rain over parts of southern Vietnam, Cambodia, southern Laos and eastern Thailand.  Heavy rain could cause floods in some locations.

Intense Tropical Cyclone Kyarr Moves Toward Oman

Intense Tropical Cyclone Kyarr moved toward Oman on Sunday.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Kyarr was located at latitude 18.3°N and longitude 65.2°E which put it about 460 miles (745 km) east-southeast of Masirah Island, Oman.  Kyarr was moving toward the west-northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h).  The minimum surface pressure was 932 mb.

The circulation around Tropical Cyclone Kyarr remained very symmetrical on Sunday.  Microwave satellite images seemed to indicate that there were two symmetric eye eyewalls surrounding the center of Kyarr.  Bands of showers and thunderstorms were revolving around the larger core of Tropical Cyclone Kyarr.  Storms near the core were generating upper level divergence which was pumping mass away from the tropical cyclone in all directions.

The formation of a second, outer eyewall caused the circulation around Tropical Cyclone Kyarr to increase in size.  Winds to hurricane/typhoon force extended out 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center.  The Hurricane Intensity Index (HII) for Tropical Cyclone Kyarr was 31.6.  The Hurricane  Size Index (HSI) was 19.1 and the Hurricane Wind Intensity Size Index (HWISI) was 50.7.

The formation of concentric eyewalls indicated that an eyewall replacement cycle was in progress.  Tropical Cyclone Kyarr will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Even though Kyarr will move through an environment favorable for strong tropical cyclones, it will likely weaken while the inner eyewall dissipates.

Tropical Cyclone Kyarr will move south of a ridge of high pressure over South Asia.  The ridge will steer Kyarr in a westward direction during the next few days.  On its anticipated track Tropical Cyclone Kyarr could approach the coast of Oman in three or four days.

Pablo Strengthens into a Hurricane Northeast of the Azores

Former Tropical Storm Pablo strengthened into a hurricane northeast of the Azores on Sunday.  At 11:00 a.m. EDT on Sunday the center of Hurricane Pablo was located at latitude 42.8°N and longitude 18.3°W which put it about 535 miles (865 km) northeast of Lajes, Azores.  Pablo was moving toward the north-northeast at 32 m.p.h. (52 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 983 mb.

Thunderstorms around the eye of former Tropical Storm Pablo strengthened on Sunday morning and Pablo intensified into a hurricane.  The circulation around Hurricane Pablo was still small.  Winds to hurricane force extended out about 10 miles (15 km) from the center of circulation.  Bands of showers and thunderstorms were revolving around the core of Pablo.  Winds to tropical storm force extended out 80 miles (130 km) from the center.

Hurricane Pablo was moving over water where the Sea Surface Temperature was near 18°C.  Water that cold would not normally contain enough energy to support a hurricane.  However the temperature of the air in the middle and upper troposphere is cold enough to allow for potential instability.  Convergence around the center of Hurricane Pablo generated enough rising motion to produce thunderstorms with tall, cold clouds tops around the eye at the center of the hurricane.  Enough water vapor condensed in the thunderstorms to produce a warm core which made Pablo a tropical cyclone.

Even though Hurricane Pablo is over Sea Surface Temperatures that would normal cause a hurricane to weak, Pablo could strengthen a little more during the next 12 hours.  It will move through a region where there is not a lot of vertical wind shear.  A larger low pressure system west of Pablo is likely to absorb the hurricane in a day or so.

Hurricane Pablo will move around the eastern side of the larger low pressure system.  The low will steer Pablo toward the north during the next 12 hours.  The larger low will turn Pablo toward the northwest on Monday.  On its anticipated track Hurricane Pablo is forecast to remain southwest of Ireland.

Tropical Cyclone Kyarr Strengthens to Equivalent of a Major Hurricane over Arabian Sea

Tropical Cyclone Kyarr strengthened to the equivalent of a major hurricane over the Arabian Sea on Saturday.  At 5:00 p.m. EDT on Saturday the center of Tropical Cyclone Kyarr was located at latitude 16.9°N and longitude 68.6°E which put it about 705 miles (1135 km) east-southeast of Masirah Island, Oman.  Kyarr was moving toward the west at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 944 mb.

Tropical Cyclone Kyarr intensified rapidly into the equivalent of a major hurricane during the past 36 hours.  A small eye formed at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Tropical Cyclone Kyarr.  Storms near the core of Kyarr were generating strong upper level divergence which was pumping mass away from the tropical cyclone in all directions.

The circulation around Tropical Cyclone Kyarr was very symmetrical.  Winds to hurricane/typhoon force extended out 40 miles (65 km) from the center of circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center.  The Hurricane Intensity Index (HII) was 25.1.  The Hurricane Size Index (HSI) was 15.1 and the Hurricane Wind intensity Size Index (HWISI) was 40.2.

Tropical Cyclone Kyarr will move through an environment favorable for intensification during the next 12 to 24 hours.  Kyarr will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Tropical Cyclone Kyarr could strengthen during the next 24 hours.  An inner rainband could wrap around the eye and eyewall at some point.  That would start an eyewall replacement cycle which would cause Kyarr to weaken.

Tropical Cyclone Kyarr will move south of a ridge of high pressure over South Asia.  The ridge will steer Kyarr toward the west during the next few days.  On its anticipated track Tropical Cyclone Kyarr will move toward Oman.

Tropical Storm Olga Develops over Gulf of Mexico, Pablo near the Azores

Tropical Storm Olga developed over the Gulf of Mexico and Tropical Storm Pablo formed near the Azores on Friday afternoon.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Olga was located at latitude 26.3°N and longitude 93.2°W which put it about 260 miles (420 km) south of Lake Charles, Louisiana.  Olga was moving toward the north-northeast at 18 m.p.h. (30 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 998 mb.

A reconnaissance plane found that former Tropical Depression Seventeen had strengthened by Friday afternoon and the National Hurricane center designated the system as Tropical Storm Olga.  More thunderstorms developed near the center of Olga and the plane found that the minimum surface pressure had decreased to 998 mb.  Bands of showers and thunderstorms were also developing around the tropical storm.  The strongest rainbands were in the eastern half of the circulation.  Bands in the western half of the circulation consisted of more showers and lower clouds.  Storms near the center were generating upper level divergence which was pumping mass away to the northeast of Tropical Storm Olga.  Winds to tropical storm force extended out about 90 miles (145 km) from the center of circulation in the northeastern quadrant of Olga.

Tropical Storm Olga could strengthen a little more during the next 12 hours.  Olga will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough over the south central U.S. and Mexico will produce southwesterly winds which will blow toward the top of the circulationn. Those winds will produce moderate vertical wind shear, which will inhibit intensification.  However, the shear will not be strong enough to prevent intensification while the Olga is over the Gulf of Mexico.  The wind shear will cause Tropical Storm Olga to start a transition to an extratropical cyclone.  A cold front will move toward Olga from the northwest and the tropical storm could merge with the front during the next 24 hours.

The upper level trough will steer Tropical Storm Olga toward the north during the next several days. On its anticipated track Olga will make landfall on the coast of Louisiana during Friday night.  Tropical Storm Olga will bring  gusty winds to coastal Louisiana. Olga is likely to drop heavy rain over parts of Louisiana, Mississippi, and eastern Arkansas. The rain could cause floods in some locations.

Elsewhere over the Atlantic Ocean, visible satellite images revealed that a tiny tropical storm had developed at the center of a much larger low pressure system west of the Azores on Friday afternoon.  The National Hurricane Center designated the system as Tropical Storm Pablo.  At 5:00 p.m. EDT on Friday the center of Tropical Storm Pablo was located at latitude 35.8°N and longitude 32.2°W which put it about 325 miles (525 km) west-southwest of the Azores.  Pablo was moving toward the east-southeast at 10 m.p.h. (16 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 990 mb.  Winds to tropical storm force extended out 35 miles (55 km) from the center of Tropical Storm Pablo.

Tropical Depression Seventeen Develops over Western Gulf of Mexico

Tropical Depression Seventeen developed over the western Gulf of Mexico on Friday.  At 11:00 a.m. EDT on Friday morning the center of Tropical Depression Seventeen was located at latitude 25.6°N and longitude 94.4°W which put it about 320 miles (515 km) south-southwest of Lake Charles, Louisiana.  It was moving toward the north at 16 m.p.h. (26 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 1006 mb.

More thunderstorms developed near the center of a low pressure system over the western Gulf of Mexico on Friday morning and the National Hurricane Center designated the system as Tropical Depression Seventeen.  Bands of showers and thunderstorms were also developing around the depression.  The strongest rainbands were in the eastern half of the circulation.  Bands in the western half of the circulation consisted of more showers and lower clouds.  Storms near the center were generating upper level divergence which was pumping mass away to the northeast of the depression.

Tropical Depression Seventeen is likely to strengthen during the next 12 to 18 hours.  The depression will move over water where the Sea Surface Temperature is near 28°C.  An upper level trough over the south central U.S. and Mexico will produce southwesterly winds which will blow toward the top of the depression.  Those winds will produce moderate vertical wind shear, which will inhibit intensification.  However, the shear will not be strong enough to prevent intensification while the depression is over the Gulf of Mexico.  The wind shear will cause the depression to start a transition to an extratropical cyclone.  A cold front will move toward the depression from the northwest and the depression could merge with the front during the next 24 hours.

The upper level trough will steer the depression toward the north during the next several days.  On its anticipated track the depression will make landfall on the coast of Louisiana during Friday night.  The depression could be a tropical storm when it makes landfall.  It will bring gusty winds to coastal Louisiana.  The depression is likely to drop heavy rain over parts of Louisiana, Mississippi, and eastern Arkansas.  The rain could cause floods in some locations.