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Typhoon Jangmi (19W)

September 26th, 2008 Category: Tropical Cyclones

September 26th, 2009 - Typhoon JangmiJangmi

September 26th, 2009 - Typhoon Jangmi

Typhoon Jangmi - Image Enhanced

Typhoon Jangmi - Image Enhanced

Typhoon Jangmi (19W) has turned gradually poleward while rapidly intensifying over the past 12 hours. An increase in storm organization is witnessed by the appearance of a 30 nm eye in multispectral satellite imagery.

The current intensity estimate of 90 knots is consistent with Dvorak t-numbers of 4.0 from both PGTW and RJTD. Typhoon Jangmi is tracking toward a weakness in the subtropical steering ridge induced by a mid-latitude trough to the north. Upper level outflow remains very strong, particulary toward a tropical upper tropospheric trough (TUTT) cell to the northeast.

The forecast philosophy has not changed significantly since the previous issuance of the prognostic reasoning message. Typhoon Jangmi is expected to turn toward a more westward track over the next 24 hours as the mid-latitude trough to the north progresses eastward and subtropical ridging rebuilds on the poleward side of the typhoon. Typhoon Jangmi will then continue generally northwestward along the steering ridge periphery toward taiwan through tau 72. Upper level outflow is expected to remain strong and along track ocean heat content high, so further intensification is likely before the typhoon impacts any landmass. By tau 72, however, the storm circulation will likely interact with the Island of Taiwan, beginning a weakenening trend.

The current forecast is supported with good confidence by the available numerical model guidance, and lies slighlty equatorward of the consensus in the tau 0 to tau 72 period. Some erratic track motion may occur if the circulation moves farther northward and passes over central Taiwan in the tau 48 to tau 72 period.

In the extended period, a second mid-latitude trough will work to further weaken the subtropical steering ridge. As this weakness develops, Typhoon Jangmi may turn slightly poleward as it moves inland into southeastern China and begins to dissipate.

Although there is some disagreement among the models in the extended forecast track depiction, all show the circulation progressing well into China during this period.

source JTWC

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