Monthly Archives: December 2016

Tropical Cyclone Vardah Reorganizes Over the Arabian Sea

After moving across southern India and weakening Tropical Cyclone Vardah began to reorganize over the eastern Arabian Sea on Thursday.  At 7:00 p.m. EST on Thursday the center of Tropical Cyclone Vardah was located near latitude 11.0°N and longitude 68.0°E which put it about 1140 miles (1840 km) east of Baargaal, Somalia.  Vardah was moving toward the west at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 35 m.p.h. (55 km/h).  The minimum surface pressure was 1007 mb.

Tropical Cyclone Vardah retained a well organized low level circulation as it moved across southern India and into the eastern Arabian Sea.  However, almost all of the showers and thunderstorms dissipated as the cyclone crossed over land.  A few showers and thunderstorms began to redevelop about 24 hours ago.  There are now several rainbands that are spiraling around the circulation and stronger thunderstorms are forming in some of those bands.  The thunderstorms are beginning to produce upper level divergence.

Tropical Cyclone Vardah will be moving through an environment that is favorable for intensification.  Vardah will be moving over water where the Sea Surface Temperature is near 28°C.  The upper level winds are weak and there is not much vertical wind shear.  Tropical Cyclone Vardah should continue to redevelop during the next 24 hours.

A subtropical ridge to the north of Vardah has been steering the tropical cyclone toward the west and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Vardah will move across the Arabian Sea toward eastern Africa during the next several days.

Tropical Cyclone Vardah Moving Across Southern India

Tropical Cyclone Vardah made landfall near Chennai and moved westward across southern India on Monday.  At 8:00 p.m. EST on Monday the center of Tropical Cyclone Vardah was located at latitude 13.1°N and longitude 77.9°E which put it about 60 miles (100 km) east of Bangalore, India.  Vardah was moving toward the west at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1005 mb.

Tropical Cyclone Vardah was the equivalent of a hurricane when it made landfall and it brought strong winds and heavy rain to the area around Chennai, India.  Vardah weakened steadily after making landfall and most of the thunderstorms have weakened.  The spiral bands still contains scattered showers, but the winds have diminished.  The low level circulation is still well organized and there is a distinct center of low pressure at the surface.

A subtropical ridge to the north of Vardah continues to steer the tropical cyclone toward the west.  On its anticipated track Tropical Cyclone Vardah is expected to move over the Arabian Sea near Mangalore in about 24 hours.  Some numerical models are suggesting that Tropical Cyclone Vardah could reorganize after the center moves back over the water.

Tropical Cyclone Vardah Nearing Landfall in India

Tropical Cyclone Vardah moved steadily toward a landfall near Chennai India on Sunday.  At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Vardah was located at latitude 13.2°N and longitude 81.1°E which put it about 60 miles (105 km) east of Chennai, India.  Vardah was moving toward the west 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/h).  The minimum surface pressure was 967 mb.

The Indian Meteorological Department’s radar at Chennai shows that Tropical Cyclone Vardah is very well organized and symmetrical.  There is a circular eye surrounded by a ring of strong thunderstorms.  The strongest storms are west and south of the eye, and the ring is thinner east of the eye.  There are multiple bands of thunderstorms and the heaviest thunderstorms in those bands are also in the western half of the circulation.  The thunderstorms are generating strong upper level divergence which is pumping out mass to the west and north of the tropical cyclone.

Tropical Cyclone Vardah is moving over water where the Sea Surface Temperature is near 29°C.  The energy from the ocean will keep Vardah from weakening before it makes landfall.  Tropical Cyclone Vardah will weaken steadily once it begins to move over southern India.

A subtropical ridge north of Vardah is steering the tropical cyclone toward the west and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Vardah will make landfall near Chennai, India in a few hours.  Vardah will continue to move west across southern India after it moves inland.

Tropical Cyclone Vardah will bring strong winds and heavy rain to the area around Chennai.  The Hurricane Intensity Index (HII) is 12.7.  The Hurricane Size Index (HSI) is 11.3 and the Hurricane Wind Intensity Size Index (HWISI) is 24.0.  Those indices indicate that Tropical Cyclone Vardah is capable of causing regional minor wind damage when it makes landafall.

Vardah will also generate a storm surge along portion of the coast north of Chennai where the wind will blow the water toward the coast.  Vardah will produce locally heavy rain over Tamil Nadu, Andhra Pradesh and Karnataka.  The heavy rain could produce floods and mudslides.

Tropical Cyclone Vardah Reaches Hurricane Intensity

Tropical Cyclone Vardah intensified into the equivalent of a hurricane on Saturday as it moved across the Bay of Bengal toward India.  At 4:00 p.m. EST on Saturday the center of Tropical Cyclone Vardah was located at latitude 13.0°N and longitude 84.8°E which put it about 290 miles (470 km) east of Chennai, India.  Vardah was moving toward the west at 13 m.p.h. (21 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 974 mb.

The circulation of Tropical Cyclone Vardah is well organized, but the distribution of thunderstorms is asymmetrical.  There is a broken ring of thunderstorms around the center of circulation.  Outside of that ring most of the thunderstorms are forming in the western half of the circulation.  It appears that an upper level ridge to the north of Vardah is producing easterly winds which are causing moderate vertical wind shear.  The wind shear seems to be the primary cause of the asymmetry of the convection.  The thunderstorms are generating upper level divergence which is pumping out mass to the west of the cyclone.

The environment around Tropical Cyclone Vardah is marginal for further intensification.  Vardah is moving over water where the Sea Surface Temperature is near 29°C.  However, the moderate vertical wind shear may be strong enough to inhibit further intensification.  There are some indications that the upper level winds may be getting stronger and the shear could increase.  If the shear increases, then Tropical Cyclone Vardah could start to weaken even though it is over warm water.

The same ridge that is causing the wind shear is also steering Tropical Cyclone Vardah toward the west and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Vardah could make landfall near Chennai, India in about 36 hours.  Tropical Cyclone Vardah will bring gusty winds and locally heavy rain to portions of southern India.  The heavy rain could cause flooding and mudslides.  Vardah will also cause a storm surge along the coast near and to the north of where the center makes landfall.

Tropical Cyclone Vardah Turns Toward India and Strengthens

Tropical Cyclone Vardah turned toward India and strengthened on Friday.  At 4:00 p.m. EDT on Friday the center of Tropical Cyclone Vardah was located at latitude 12.5°N and longitude 88.7°E which put it about 500 miles (800 km) southeast of Visakhapatnam, India.  Vardah was moving toward the west-northwest at 13 m.p.h. (21 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 985 mb.

Many more thunderstorms formed around the core of Tropical Cyclone Vardah and it exhibited a more symmetrical, circular shape on Friday.  The increasing organization of the circulation include multiple spiral rainbands in the outer portions of the cyclone.  The thunderstorms near the core of Vardah generated strong upper level divergence which pumped out mass and allowed the pressure to decrease more quickly.  An increased pressure gradient force generated stronger winds.

The environment around Tropical Cyclone Vardah has become much more favorable for intensification.  An upper level ridge to the east of Vardah was causing southeasterly winds and was producing moderate vertical wind shear.  Those winds have diminished and the wind shear is much less.  Since Vardah is moving over water where the Sea Surface Temperature is near 29°C, it is efficiently extracting energy from the ocean.  Tropical Cyclone Vardah will continue to intensify during the next 24 hours and it could intensify rapidly.  Vardah is likely to become the equivalent of a hurricane on Saturday.

A subtropical ridge north of Vardah is strengthening and building toward the west.  The ridge is steering Tropical Cyclone Vardah toward the west-northwest and that general motion is expected to continue.  On its anticipated track Tropical Cyclone Vardah could approach the coast of southeast India in two or three days.

Tropical Cyclone Vardah could bring strong winds and heavy rain to parts of southeastern India in three or four days.

Tropical Cyclone Forms Near Andaman Islands

A tropical cyclone formed near the Andaman Islands over the Bay of Bengal on Wednesday.  At 10:00 p.m. EST on Wednesday the center of Tropical Cyclone 05B was located at latitude 11.6°N and longitude 92.1°E which put it about 710 miles (1145 km) southeast of Visakhapatnam, India.  The tropical cyclone was moving toward the north-northeast 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 65 m.p.h. (105 km/h).  The minimum surface pressure was 997 mb.

An area of thunderstorms moved from the western Pacific Ocean into the southeastern Bay of Bengal.  The area of thunderstorms turned slowly northward near the Nicobar and Andaman Islands.  A distinct center of circulation began to organize inside the area of thunderstorms.  The Indian Meteorological Department classified the low pressure area as a depression and the Joint Typhoon Warning Center designated the system as Tropical Cyclone 05B.

The circulation of Tropical Cyclone 05B is still organizing.  A primary band of thunderstorms wraps around the northern and western side of the center of circulation.  Additional bands of thunderstorms are forming in the eastern half of the circulation.  Microwave satellite imagery suggests that an eye could be developing in the middle levels of the circulation.  The thunderstorms near the center are generating upper level divergence that is pumping out mass toward the northeast of the tropical cyclone.

Tropical Cyclone will be moving through an environment that is favorable for intensification.  It will be moving over water where the Sea Surface Temperature is near 29°C.  An upper level ridge to the west of the cyclone is producing northerly winds which are blowing across the top it.  However, the vertical wind shear is not significantly inhibiting the organization of the tropical cyclone.  Tropical Cyclone 05B could reach hurricane intensity in a couple of days.

A subtropical ridge is currently steering Tropical Cyclone 05B toward the north.  The center is moving just to the west of the Andaman Islands.  The subtropical ridge is forecast to strengthen and build toward the west.  As the ridge strengthens and extends farther west, it will start to steer the tropical cyclone toward the west.  On its anticipated track Tropical Cyclone 05B could approach the east coast of India in three or four days.

Tropical Cyclone 05B will continue to bring gusty winds and heavy rain to parts of the Andaman Islands on Thursday.  The tropical cyclone could bring strong winds, locally heavy rain, a storm surge and mudslides to southern India in a few days.