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Tropical Cyclone Anggrek (02S) Tracks West-Southwestward – November 4th, 2010

14.2S 95.8E

November 4th, 2010 Category: Image of the day, Tropical Cyclones

Tropical Cyclone Anggrek (02S) - November 3rd, 2010

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Track of TC 02S

Tropical Cyclone Anggrek (02S), located approximately 180 nm south-southwest of the Cocos Islands, has tracked west-southwestward at 07 knots over the past six hours. Maximum significant wave height is 15 feet.

Animated infrared imagery depicts an exposed, well-defined low-level circulation center (LLCC) with deep convective banding over the southeast quadrant. Animated water vapor imagery depicts increasing northerly vertical wind shear (VWS) over the past 12 hours.

Imagery and recent upper-level wind data indicate 20-30 knot northerly flow associated with an anticylone near 12S 103E. Eespite the increased VWS and exposed LLCC, an ASCAT image supports a well-defined, symmetric wind field with numerous 30-35 knot winds.

The current intensity was assessed at 40 knots based on the ASCAT low bias as well as Dvorak current intensity estimates ranging from 35 to 45 knots.

TC 02S is tracking west-southwestward along the northern periphery of a finger of the low- mid-level subtropical ridge. The model trackers are in good agreement through TAU 48 with the exception of WBAR, which tracks the system southward through southeastward.

Anggrek is expected to weaken through the period due to cooler SST and increasing VWS after TAU 24 associated with an approaching, deepening shortwave trough, and should dissipate as a significant TC in the next 24-36 hours.

Tropical Cyclone Anggrek (02S) Expected to Steadily Intensify

4.2S 95.8E

November 2nd, 2010 Category: Tropical Cyclones

Tropical Cyclone Anggrek (02S) - November 1st, 2010

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Track of TC 02S

Tropical Cyclone Anggrek (02S), located approximately 70 nm
southeast of the Cocos Islands, has tracked southward at 05
knots over the past six hours. Maximum significant wave height is 20 feet.

Animated multispectral satellite imagery (MSI) shows tightly wrapped low level convective banding with central deep convection. There is uncertainty in the initial position due to deep convection obscuring the low level circulation center (LLCC) in MSI. The initial intensity estimates range from 45 to 55 knots.

Upper level analysis indicates TC 02S is located just north of the subtropical ridge axis in an area of low vertical wind shear and divergence aloft. The system is currently tracking along a mid-level subtropical steering ridge centered to the east of the LLCC.

The subtropical steering ridge is expected to re-build to the southeast and allow TC 02S to turn southwestward within the initial TAUs. Additionally, the system is expected to steadily intensify as it continues to track into a more favorable upper level environment and over water with marginal ocean heat content.

Around TAU 48, a mid-level, upper level trough is expected to weaken the steering ridge to allow the system to turn poleward. TC 02S should begin to weaken with increased vertical wind shear associated with the upper level trough and decreasing ocean heat content and then dissipate as a significant tropical cyclone by TAU 96.

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.

Tropical Cyclone Bongani (02S) Near Northern Madagascar

9.1S 52.0E

November 24th, 2009 Category: Tropical Storms

Tropical Cyclone Bongani - November 23rd, 2009

Tropical Cyclone Bongani - November 23rd, 2009

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

Track of TC 02S

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Tropical Cyclone Bongani (02S), partially visible along the right edge, is located approximately 685 nm north-northeast of Antananarivo, Madagascar (below). The system has tracked west-southwestward at 6 knots over the past six hours.

Animated infrared satellite imagery indicates increasingly disorganized deep convection, however, a recent METOP-A image depicts a partially exposed but well-defined low-level circulation center (LLCC) with convective banding over the western semi-circle.

The current intensity of 45 knots is higher than the Dvorak estimates of 35 knots based on an ASCAT image (25-km) showing 40-45 knot unflagged winds.

TC 02S is forecast to track slowly west-southwestward through TAU 48 under the steering influence of a weak low- to mid-level subtropical ridge (STR) then is forecast to accelerate more southwestward after TAU 72 as the STR strengthens and shifts east of Madagascar. The majority of the model guidance indicates the system will likely turn poleward over water, while one model suggests the system could turn poleward later, as it tracks over Mozambique.

Bongani is forecast to intensify slowly but should strengthen after TAU 48 due to improved poleward outflow. TC 02S will likely weaken after TAU 96 due to increased vertical wind shear associated with the approaching midlatitude shortwave trough. Maximum significant wave height is 12 feet.

Tropical Cyclone 02S Forms in the Indian Ocean

November 19th, 2008 Category: Tropical Cyclones

Tropical Cyclone 02S - November 19th, 2008

Tropical Cyclone 02S - November 19th, 2008

Tropical Cyclone 02S - enhanced image

Tropical Cyclone 02S - enhanced image

Tropical Cyclone 02S, located in the Indian Ocean approximately 185 nautical miles northeast of Cocos Island, has tracked east-southeastward at 12 knots over the past six hours.

Recent imagery depicts a well-consolidated low level circulation center (LLCC) with improving deep convection wrapping into the west and south sides of the circulation.

Although convection has decreased slightly over the past 12 hours, recent imagery shows a resurgence in convective activity with banding becoming tighter and better defined.

The LLCC lies beneath a weakly developing upper-level anticyclone in an area of moderate easterly vertical wind shear.

This, coupled with relatively weak ocean heat content values may serve to limit the maximum intensity of the system.

Maximum sustained surface winds are estimated at 30 to 35 knots, with 30 to 40 knot winds near the center. Maximum significant wave height is 8 feet.

The system is expected to track east-southeastward over the next 48 hours under the influence of low- to mid-level westerly flow equatorward of the system.

source JTWC