Monthly Archives: November 2015

Tropical Cyclone Megh Moving Slowly West Over the Arabian Sea

Tropical Cyclone Megh moved slowly westward over the Arabian Sea on Friday.  At 4:00 p.m. EDT on Friday the center of Tropical Cyclone Megh was located at latitude 12.9°N and longitude 60.4°E which put it about 420 miles (680 km) east of Socotra Island, Yemen.  Megh was moving toward the west at 7 m.p.h. (11 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 990 mb.

The convection around Tropical Cyclone Megh diminished earlier today, but more thunderstorms have formed near the center of circulation during the past few hours.  Megh has a well formed, symmetrical circulation with an eyelike feature at the center.  It is a small cyclone and tropical storm force winds only extend out about 50 miles (80 km) from the center.  The new thunderstorms near the center of circulation are starting to generate upper level divergence.

Aside from the possible drier air, the environment surrounding Tropical Cyclone Megh is favorable for intensification,  It is over water where the Sea Surface Temperature is near 28°C.  The winds in the upper levels are light and there is not much vertical wind shear.  Now that thunderstorms are redeveloping near the core of the circulation, Tropical  Cyclone Megh should begin to intensify and it is still likely to reach hurricane intensity in a day or two.

A ridge north of Megh is steering the tropical cyclone toward the west and that general motion is expected to continue during the weekend.  On its anticipated track, Tropical Cyclone Megh could approach Socotra Island, Yemen in about 36 hours.  It could be the equivalent of a hurricane at that time.  Given the prior damage caused by Tropical Cyclone Chapala, Megh could have a significant impact on Socotra Island.

Disturbance Brings Squally Weather to the Northwest Caribbean Sea

A complicated disturbance over the northwestern Caribbean Sea is bringing squally weather to that area.  A tropical wave over the western Caribbean Sea is interacting with an upper level low over eastern Mexico.  The disturbance is causing thunderstorms over a region that extends from the northwestern Caribbean Sea to the southern Gulf of Mexico.  Upper level divergence east of the upper low has led to the formation of a surface low pressure system east of Belize.  At 7:00 p.m. EST on Thursday the center of the surface low was located at latitude 18°N and longitude 86°W which put it about 150 miles (240 km) east-southeast of Chetumal, Mexico.  The surface low was moving toward the west-northwest at 10 m.p.h. (16 m.p.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 1011 mb.

The disturbance is not very well organized, which is normally the case when a tropical wave interacts with an upper level low.  There is a broken area of thunderstorms that extends around the east and northern sides of the disturbance.  However, there are not many thunderstorms close to the center of the surface low.  The upper low is causing vertical wind shear over the western half of the surface low.  Some upper level divergence is occurring over the eastern half of the surface low.

A large high pressure system over the western Atlantic Ocean is steering the disturbance toward the west-northwest.  That general steering pattern is expected to continue for the next two days.  On its anticipated track the disturbance will move over the Yucatan peninsula and over the southern Gulf of Mexico during the next several days.

The disturbance is in an environment that is marginally favorable for tropical development.  The Sea Surface Temperature of the northwestern Caribbean is near 29°C.  There is vertical wind shear, but it may be just small enough to allow for slow development.  On the other hand, the disturbance will move over the Yucatan peninsula which will further inhibit development.  There may also be a chance for development after the disturbance moves over the southern Gulf of Mexico.  The National Hurricane Center is giving a 20% probability of tropical cyclone formation out of the disturbance.

Tropical Cyclone Megh Forms Over the Arabian Sea

A new tropical cyclone, designated with the name Megh, formed Thursday over the same portion of the Arabian Sea where Tropical Cyclone Chapala developed.  At 4:00 p.m. EST on Thursday the center of Tropical Cyclone Megh was located at latitude 13.6°N and longitude 63.0°E which put it about 640 miles (1030 km) east of Socotra Island, Yemen.  Megh was moving toward the west-southwest at 6 m.p.h. (10 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 994 mb.

Tropical Cyclone Megh exhibited increased organization on Thursday.  A core of thunderstorms developed near the center of circulation and a primary rainband spirals around the northern and western sides of the tropical cyclone.  The thunderstorms near the core of Megh are beginning to generate upper level divergence, especially toward the east.

Tropical Cyclone Megh is an environment favorable for intensification.  It is over water where the Sea Surface Temperature is near 28°C.  An upper level ridge north of Megh is generating light northeasterly winds over the top of the tropical cyclone, but the vertical wind shear is modest.  Megh should continue to intensify and it could reach the equivalent of hurricane intensity in a day or two.

The ridge is steering Tropical Cyclone Megh a little south of due west and that general steering motion is expected to continue for several days.  On its anticipated track, Tropical Cyclone Megh could approach Socotra Island, Yemen in 48 to 60 hours.  Since the outer portions of Tropical Cyclone Chapala caused damage on Socotra Island, a direct hit by Tropical Cyclone Megh could have a significant impact there.

Tropical Cyclone Chapala Makes Landfall in Yemen

Tropical Cyclone Chapala made landfall in Yemen just west of Al Mukalla as the equivalent of a hurricane.  At 10:00 p.m. EDT on Monday the center of Tropical Cyclone Chapala was located at latitude 13.9°N and longitude 48.7°E which put it 30 miles (50 km) south of Al Mukalla, Yemen.  Chapala was moving toward the west-northwest at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (170 km/).  The minimum surface pressure was 979 mb.

Tropical Cyclone Chapala reached the western end of the ridge that was steering it toward the west and it turned north toward the coast of Yemen on Monday.  When Chapala reached the western end of the ridge, southerly winds in the upper levels generated vertical wind shear and the circulation of the tropical cyclone tilted toward the north.  In addition, as the core of the circulation neared the coast, it drew in drier air from the Arabian peninsula.  The combination of more wind shear and drier air started to weaken Chapala, but the tropical cyclone was still the equivalent of a hurricane when it made landfall.

The core of Tropical Cyclone Chapala will bring strong winds and heavy rain to the coast.  Although Chapala will weaken fairly quickly as it moves into the dry interior of the Arabian peninsula, the circulation will be capable of producing locally heavy rainfall and flash floods as the tropical cyclone spins down.

Tropical Cyclone Chapala Poised to Enter Gulf of Aden

Tropical Cyclone Chapala continued to move steadily westward on Sunday and it was poised to enter the Gulf of Aden.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Chapala was located at latitude 13.2°N and longitude 52.2°E which put it about 230 miles (370 km) east-southeast of Al Mukalla, Yemen.  Chapala was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h).  The minimum surface pressure was 959 mb.

Chapala is still a very well organized tropical cyclone and it is the equivalent of a major hurricane.  Chapala has a 25 mile (40 km) wide eye, which is surrounded by numerous thunderstorms.  Those storms are generating upper level divergence which is pumping out enough mass to balance the air flowing into the center near the surface.  The balance of inflow and outflow allowed Chapala to maintain its intensity on Sunday.

Tropical Cyclone Chapala is over water where the Sea Surface Temperature is around 28.5°C and the upper level winds are light.  There is little vertical wind shear and most environmental factors support the ability of Tropical Cyclone Chapala to maintain its intensity.  However, once Chapala enters the Gulf of Aden it will have very dry air to its north over the Arabian peninsula and dry air to its south over east Africa.  Chapala will remain a strong tropical cyclone as long as the dry air does not reach its core.  However, as Tropical Cyclone Chapala moves closer to the coast of Yemen, the drier air will probably cause it to start to weaken.

A ridge north of Chapala is steering the tropical cyclone toward the west.  Chapala will reach the western end of the ridge on Monday and the tropical cyclone will turn toward the northwest.  On its anticipated track Chapala will make landfall on the coast of Yemen near Al Mukalla in 24 to 30 hours.  It will bring strong winds and heavy rain to the coast.  Chapala is likely to dissipate quickly as it moves inland over the Arabian peninsula, but it could bring heavy rain and flash floods before it does so.

Strong Tropical Cyclone Chapala on Track for Landfall in Yemen

Strong Tropical Cyclone Chapala moved steadily westward on Saturday and it remains on track for a landfall in Yemen.  At 11:00 p.m. EDT on Saturday the center of Tropical Cyclone Chapala was located at latitude 13.6°N and longitude 56.0°E which put it about 265 miles (425 km) south-southeast of Salalah, Oman and about 465 miles (765 km) east of Al Mukalla, Yemen.  Chapala was moving toward the west at 10 m.p.h. (16 km/h).  The maximum sustained wind speed was 135 m.p.h. (215 km) and there were wind gusts to 160 m.p.h. (260 km/h).  The minimum surface pressure was 952 mb.

Chapala continues to be a strong well organized tropical cyclone and it is the equivalent of a major hurricane.  It has a symmetrical circulation with a well formed eye inside a core of thunderstorms.  Multiple rainbands are rotation around the center of circulation.  Upper level divergence is pumping out mass in all directions.

Tropical Cyclone Chapala remains in a favorable environment.  It is over warm Sea Surface Temperatures and the upper level winds are light.  There is not much vertical wind shear and Chapala could maintain its intensity until it approaches the coast of Yemen.  When Chapala gets nearer the coast, it will start to pull in drier air from the Arabian peninsula.  As Chapala ingests the drier air, it will start to weaken.

A ridge north of Chapala is steering the tropical cyclone westward.  As Chapala nears the western end of the ridge, it will start to turn more toward the west-northwest.  On its anticipated track Tropical Cyclone Chapala will approach the central coast of Yemen in 36 to 48 hours.  The core of Chapala will pass north of the island of Socotra on Sunday.