Thursday, July 14, 2011

Typhoon Ma-On Update #8

Typhoon Ma-On continues to intensify as it slowly moves away from the Mariana Islands. TY Ma-On was last located approximately 760km north northwest of Guam. Maximum sustained winds have increased to 185kph with gusts up to 230kph. Ma-On is moving westward at 23kph. Ma-On is now a Category 3 typhoon on the Saffir-Simpson Scale.

A Tropical Storm Warning is still in effect for Pagan, Agrihan, and Alamagan.

Scattered thunderstorms will continue to affect CNMI and Guam throughout today coupled with strong winds and rough waves.

Latest IR image shows that the northern half of the storm remains impinged by the subsidence (sinking air) and dry air north of the storm. Water vapor image also shows that Ma-On is now trying to develop a Poleward Outflow Channel although it is still battling dry air on the western side of the storm. Ma-On's southern half, however, remains in excellent condition and that is why agencies and Dvorak estimates continue to increase the strength of this storm, albeit at a slow pace.

Computer models, meanwhile, are also in better agreement with 3 models (GFS, CMC, and NGX) all showing a landfall somewhere in Shikoku; GFS actually just skirts the southern coast of Japan before recurving towards the North Pacific. The ECMWF, on the other hand, shows a landfall in Kyushu as a strong Typhoon. The UKMET remains the westernmost outlier, still showing that straight-runner and a sharp recurve towards Okinawa.

The critical part of the steering, aside from the strength of the STR, is observing the effects of a developing disturbance east of the Philippines (Invest 92W). If it does develop, it could influence somewhat Typhoon Ma-On as it nears this disturbance. Looking at the models, it seems UKMET is overdoing the Direct Cyclone Interaction but we'll still have to see the effects it will have, if any.

Latest IR still showing cold cloud-tops, mainly to the south and southwest of the center. A recent AMSRE microwave image also shows a developing low level circulation with the bulk of activity remaining in the south. A TCFA alert is still posted and JMA continues to show this as a tropical depression.

Another update will be posted at 3pm (Philippine Time) today with our updated forecast track.
Issued (21 UTC) 5am PhT 071511

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