Friday, September 16, 2011

Tropical Storm Roke Update #5

Note: No Video Updates for today.

Tropical Storm Roke has slightly intensified and has begun to really slow down. It was last located approximately 220km east of Okinawa. Maximum sustained winds have increased to 75kph gusting to 100kph. Roke is moving west northwestward at 5kph.

Latest radar from JMA showing bands of moderate rain offshore of Okinawa. Winds are also beginning to pick up in the islands, ranging from 25 to 40kph with gale force gusts. This is expected to increase throughout tonight and into tomorrow.

Radar from JMA showing Okinawa, for more images click HERE

I also want to mention the islands of Kyushu and Shikoku. Even though these areas are well north of Roke, the storm's outflow is actually enhancing the formation of thunderstorms and widespread heavy rain. Some places have already received more than 100mm just for today and we can expect another 100 to 200mm of rain for the next 24 hours.

Radar showing Shikoku with rain rates of between 5 to 20mm/hr with some bands of VERY HEAVY rain rates of more than 30mm/hr!!! Please beware of flooding and landslides in these areas.

Going back to TS Roke, you can see in the VIS image below the improving overall appearance on the satellite. Wind shear remains very weak and sea surface temperatures are warm. TS Roke is facing some subsidence and dry air to the northwest that is limiting intensification. Short-term forecast (indicated by the blue arrow) showing Roke to move southwestward and track just east of Okinawa tomorrow.

VIS Image from NRLMRY

Medium and long-term forecasts still have a significant spread among computer models. We do know Roke will stall or at least drift slowly around Okinawa for at least two days. The subtropical ridge is now weakening as expected and this will put Roke in a very weak steering environment. For now, we are forecasting Roke to begin turning to the north by Monday as a trough approaches from East Asia. Roke will then track to the northeast and could intensify further by that time frame.

Personal Forecast (NOT OFFICIAL)

We'll have another update tomorrow.
Issued (0930 UTC) 530pm PhT 091611

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