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Archive for Tropical Storms

Tropical Cyclone Laurence (06S) Continues Land Interaction by Australian Coast – December 17th, 2009

17.9S 122.2E

December 17th, 2009 Category: Image of the day, Tropical Storms

Tropical Cyclone Laurence (06S) - December 16th, 2009

Tropical Cyclone Laurence (06S) - December 16th, 2009

Track of TC 06S - December 16th, 2009 © Univ. of Wisconsin

Track of TC 06S

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Tropical Cyclone Laurence (06S), located approximately 130 nm east-northeast of Broome, Australia, has tracked southward at 2 knots over the last six hours. Animated infrared satellite imagery shows that the system has tracked onto land and is starting to slow down.

Model guidance indicates TC 06S will continue to track under the influence of a mid-level ridge located over the western portion of central Australia. The ridge is expected to re-align over the next 48 hours, causing the track to shift to a more westward direction.

As the system weakens the steering will shift to the lower levels, and surface ridging across southern Australia will help to keep the low level tracking towards the coast again around TAU 48. Land effects and increasing vertical wind shear will weaken the system throughout the next 48 hours, and is not expected to re-develop after approaching the coast. However, there are some models suggesting the system could track back over water and re-develop.

Tropical Cyclone Ward (05B) Makes Landfall Near Trincomalee, Sri Lanka

8.5N 81.2E

December 15th, 2009 Category: Tropical Storms

Tropical Cyclone Ward (05B) - December 13th, 2009

Tropical Cyclone Ward (05B) - December 13th, 2009

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Tropical Cyclone Ward (05B), located approximately 140 nm northeast of Colombo, Sri Lanka, has tracked west-southwestward at 3 knots over the past six hours. The current intensity is based on Dvorak estimates of 30 knots. Maximum significant wave height is 10 feet.

Animated multispectral satellite imagery indicates that the low level circulation center (LLCC) has become increasingly disorganized with bursts of deep convection east of the center. A TRMM 37V Ghz image shows that the LLCC is located along the east coast of Sri Lanka with weakly curved banding.

After wandering some time to the east of Sri Lanka, the system made landfall near Trincomalee on December 14th. TC 05B is currently drifting west-southwestward and is expected to continue tracking across the east coast of Sri Lanka, and dissipate within the next 12 hours.

Tropical Cyclone Laurence (06S) Makes Landfall in Australia

14.2S 128.8E

December 15th, 2009 Category: Tropical Storms

Tropical Cyclone Laurence (06S) - December 13th, 2009

Tropical Cyclone Laurence (06S) - December 13th, 2009

Track of TC 06S - December 14th, 2009 © Univ. of Wisconsin

Track of TC 06S

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Tropical Cyclone Laurence (06S) tracked through Darwin Australia this weekend before sliding back into the Timor Sea and is now forecast to make a second landfall in Australia. The storm is forecast to make landfall north of Wyndham in the Kimberley region, then parallel the coastline while moving over land for the next couple of days, heading southwest through the northern area of the Great Sandy Desert and into the Pilbara region.

Laurence is currently located approximately 250 nautical miles west-southwest of Darwin, Australia, and has tracked westward along the northwestern periphery of the mid-level subtropical steering ridge at 6 knots over the past six hours. Maximum significant wave height is 14 feet.

Upper-level analysis indicates the system is near the subtropical ridge axis and animated water vapor imagery shows good poleward and equatorward outflow. Accordingly, the system has intensified over the last 6 to 12 hours and an AMSR-E microwave image shows tightly wrapped banding and a microwave eye. Wyndham radar imagery also shows the wrapping convection and apparent low level circulation center, confirming the position.

TC 06S is expected to continue tracking generally west-southwestward along the northwestern coast of Australia throughout the forecast period. In the near term, an approaching mid-latitude trough will pass to the south but enable the steering ridge to remain oriented north-south, allowing the system to begin tracking south-southwestward over the next 24 hours.

By TAU 48, however, the system should weaken slightly as it interacts over land and it will turn more westward as a lobe of the steering ridge builds more southwestward. After TAU 96, the system should track back over very warm water and begin to re-intensify under favorable environmental conditions.

Tropical Cyclone Cleo (03S) Gradually Weakens

8.6S 63.9E

December 11th, 2009 Category: Tropical Storms

Tropical Cyclone Cleo (03S) - December 9th, 2009

Tropical Cyclone Cleo (03S) - December 9th, 2009

Track of TC 03S - December 11th, 2009 © Univ. of Wisconsin

Track of TC 03S

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On December 6th, a tropical disturbance formed in the central Indian Ocean. The storm was expected to strengthen slowly, however, the next day, the disturbance strengthened into a severe tropical storm and was designated Tropical Cyclone 03S. On December 8th, it strengthened rapidly to become the first Intense Tropical Cyclone of the southwest Indian Ocean cyclone season.

TC 03S sustained this strength for a day, as can be observed in this image from December 9th. The following day, it slowly weakened to a category 2 cyclone and continued to weaken throughout the day to a tropical storm.

Currently, Tropical Cyclone Cleo (03S), located approximately 480 nm southwest of Diego Garcia, has tracked west-northwestward at 9 knots over the past six hours. The low level circulation center remains fully exposed, and the remaining deep convection is nearly depleted.

Convection is not expected to rebuild over the center due to the continued effects of vertical wind shear and dry air. Intensity fixes concur that the system is 35 knots or less. Maximum significant wave height is 14 feet.

Tropical Cyclone Bongani (02S) Expected to Track into Mozambique Channel

9.1S 49.9E

November 25th, 2009 Category: Tropical Storms

Tropical Cyclone Bongani - November 24th, 2009

Tropical Cyclone Bongani - November 24th, 2009

Track of TC 02S - November 24th, 2009 © Univ. of Wisconsin

Track of TC 02S

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Tropical Cyclone Bongani (02S), located approximately 560 nm north-northeast of Antananarivo, Madagascar, has tracked south-southwestward at 11 knots over the past six hours. The maximum significant wave height is 13 feet.

The forecast has been shifted south of the previous forecast based on a WSAT Coriolis 37h microwave image that shows a formative microwave eye south-of-track.

Despite the improved low level microwave signature evidenced in the aforementioned microwave image, deep convection has waned over the past 12 hours. Consequently, Dvorak intensity estimates from PGTW underestimate the current intensity.

The cyclone will continue to track just south of west along the western periphery of the mid-level subtropical ridge that is building east to west. Slow intensification is expected under the influence of generally favorable environmental conditions. However, the peak intensity has been decreased to 65 knots based on the latest intensity guidance.

The forecast track will bend increasingly poleward as the cyclone tracks into the Mozambique Channel due to the influence of an approaching upper level trough that will temporarily erode and re-orient the steering ridge. In addition, the trough will provide increased poleward venting before vertical wind shear elevates beyond TAU 72. After the trough passes the forecast track will flatten and the system will track inland over interior Mozambique, and will dissipate.