Wednesday, September 14, 2011

Tropical Storm Roke Update #3 w/ Video

18W (Former Bagyong "Onyok") has intensified into a Tropical Storm and is now bearing the international name "Roke".

TS Roke was last located approximately 850km east southeast of Okinawa, moving west northwestward at 15kph. Maximum sustained winds are now at 65kph gusting to 90kph. The storm itself is still encountering some shear with the low-level center remaining fully exposed. The main convective activity is still displaced well east of the system. Aside from shear, dry air and subsidence are also hindering Roke's intensification. Nevertheless, conditions look to be improving over the next couple of days so we could see TS Roke intensify a little bit before approaching Okinawa.

Computer models are in good agreement that this will track towards Okinawa/Amami by this weekend. However, they begin to diverge into the early part of next week. The main steering influence right now is the Subtropical Ridge (STR) situated southeast of Japan and is pushing Roke west northwestward. However, that STR is forecast to weaken and reorient itself to the east by Sunday. This will leave a weak steering current near Okinawa by which time TS Roke will begin to slow down significantly and will meander in the East China Sea. Some models take it north towards Kyushu while some models are bringing Roke towards the southwest, potentially towards Taiwan.

Our 5-day forecast agrees with the consensus and we are bringing Roke near Okinawa beginning Saturday. It will then slow down and will remain near Okinawa for almost 3 days. We have very low confidence with the 3 to 5 day time frame and this will all rest on the timing of the weakening of the ridge. Hopefully we'll have a better idea on the eventual track in the coming days. Right now, it is very clear that Okinawa will begin to see some strong winds beginning Friday so hope you are beginning to prepare in that islands!

Personal Forecast (NOT OFFICIAL!)

Other systems we are watching are Invest 94W and 95W. 94W is located well east of Micronesia. The low-level center is partially exposed with convective activity beginning to wrap around the system. JTWC is giving this system a "MEDIUM" chance of developing within 24 hours. Computer models are bringing 94W to the northwest and is forecast to dissipate by early next week without affecting any land mass.

Invest 95W, meanwhile, is located just to the northeast of Luzon. It also has a ill-defined low-level center and some fragmented and weak convective activity. The environment is somewhat favorable for intensification although the proximity of TS Roke northeast of the system will like affect 95W's intensification. Nevertheless, 95W will probably bring some rains across Extreme Northern Luzon, Batanes Islands, and Taiwan. We'll continue monitoring these systems.

Video Update for more info!

We'll have another update tomorrow.
Issued (09 UTC) 5pm PhT 091411

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