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Tropical Depression 13W, Near Japan, Tracking Northeastward

29.3N 134.5E

August 12th, 2011 Category: Tropical Storms

Tropical Depression 13W - August 11th, 2011

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Track of TD 13W - August 11th, 2011 © Univ. of Wisconsin

Track of TD 13W

Tropical Depression 13W, located approximately 415 nm south of Tokyo, Japan, has tracked northeastward at 09 knots over the past six hours. Maximum significant wave height is 6 feet.

Animated infrared imagery (IR) shows a fully exposed low level circulation center (LLCC) with the most recent convective flare having completely collapsed. Other images show the exposed LLCC, no deep convection, and dry air entrainment from the west wrapping around the southeastern periphery of the system.

The initial position is based on the abovementioned IR and microwave imagery with high confidence. The initial intensity is based on PGTW and RJTD Dvorak intensity estimates of 25-30 knots. Upper level analysis and animated water vapor imagery indicate that TD 13W is south of a subtropical ridge axis and currently under moderate (10-15 knots) easterly vertical wind shear.

TD 13W is expected to continue tracking northeastward and slowly weaken due to increasingly unfavorable environmental conditions, such as decreasing ocean heat content and dry air entrainment from the west. By TAU 24 the system is expected to dissipate over water. numerical model guidance is in good agreement with the exception of ECMWF, which curves TD 13W north at TAU 24 and northwestward by TAU 36. This curve may be due to ECMWF losing track of the LLCC as the system begins to dissipate.

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