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Subtropical Depression 17W 2021

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Satellite images and tracking maps of Subtropical Depression 17W 2021, August 31 - September 3. Max wind speed 55km/h.

17W is located 2165 km southeast of Misawa, Japan, and has moved north-northwestward at 6 km/h (3 knots) over the past 6 hours.

17W is currently tracking northwestward under the influence of the subtropical ridge located to the east-northeast. In 12 hours, the system will intensify slightly to 65 km/h (35 knots) and turn northward as it begins to round the subtropical ridge axis. Afterwards, decreasing sea surface temperatures will begin to gradually weaken the system.

In 36 hours, 17W will begin to accelerate northeastward as it begins interacting with the westerlies in the baroclinic zone. In around 2 days, the system will begin to experience rapidly increasing wind shear, which in addition to further cooling sea surface temperatures, will begin extra-tropical transition (ETT).

17W is expected to complete ETT in 3 days. Forecast guidance are in good agreement in regards to forecast track with the exception of NVGM and AFUM which are western outliers. Therefore, the JTWC forecast track is placed slightly to the right of the model consensus.

Intensity guidance is in relatively fair agreement with all consensus members keeping the intensity under 65 km/h (35 knots) and then weakening the system for the remainder of the forecast period.

The JTWC intensity forecast is placed slightly above intensity consensus at 12 hours to continue the observed trend of steady intensification, and then is slightly below concensus at later times to account for weakening due to extratropical transition.

Maximum significant wave height is 3.7 meters (12 feet).

Information provided by the Joint Typhoon Warning Center (JTWC).

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