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Tropical Cyclone Dumile (07S) Expected to Accelerate, Then Weaken – January 4th, 2013

13.4S 53.6E

January 4th, 2013 Category: Image of the day, Tropical Storms

Tropical Storm 07S – January 2nd, 2013

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Track of Tropical Storm 07S - January 2nd, 2013 © Univ. of Wisconsin

Track of TS 07S

Tropical Cyclone Dumile (07S), located approximately 260 nm south-southwest of La Reunion, has tracked southward at 11 knots over the past six hours. Maximum significant wave height is 32 feet.

Animated multispectral satellite imagery indicates the system remains well defined with a ragged eye but has started to elongate as the banding to the north continues to weaken. An SSMIS 91 ghz microwave image continues to show a large microwave eye with the northern eyewall becoming shallow as it further degrades.

The initial intensity is maintained at 70 knots, based on the average of Dvorak intensity estimates from PGTW and KNES ranging from 65 to 77 knots. There is high confidence in the initial position based on the eye feature in the aforementioned imagery.

Upper-level analysis and animated water vapor imagery indicate that TC 07S has strong poleward outflow into the westerlies to the south as well as an equatorward outflow channel which has weakened in the past 12 hours as the system drives further south.

Dumile currently lies in an area of moderate (10-20 knots) vertical wind shear (VWS). It is tracking southward along the western periphery of the deep subtropical ridge (STR) positioned to the east. The system is forecast to turn to the southeast as it recurves around the STR and start to accelerate in the next 12 hours, weakening slightly.

TC 07S will begin extra-tropical transition (ETT) at TAU 24, and then weaken rapidly through TAU 36 due to increasing VWS and rapidly cooling SSTs as it completes ETT. Numerical model guidance remains in tight agreement, supporting the JTWC forecast track with high confidence.

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