Tuesday, August 21, 2012

Tropical Storm Bolaven Update #4

Tropical Storm Bolaven continues to intensify as it slowly moves away from the Marianas. The system was last located approximately 700km northwest of Guam or about 700km south of Iwo To. Maximum sustained winds are now up to 100kph with gusts of up to 130kph. Bolaven is currently moving west northwestward at 10kph.

IR Image from NRLMRY

Latest satellite image shows the central dense overcast of Bolaven becoming more organized. We are also seeing very cold cloud tops across the storm indicating strong convective activity within. Equatorward outflow has also improved in the past 24 hours with the poleward outflow also forecast to improve in the next 2 days. Bolaven successfully absorbed the remnants of Invest 98W last night and is now on its way to intensifying at a faster pace.

Based on the latest movement, Bolaven could enter the Philippine Area of Responsibility tomorrow evening (Wednesday); acquiring the local name 'Bagyong Julian'. By that time, we expect Bolaven to have intensified into a Typhoon. It will then continue moving west northwestward under the influence of the Subtropical Ridge. As Bolaven is forecast to remain in favorable conditions throughout its lifetime, it could undergo a period of Rapid Intensification by Thursday or Friday. By Saturday, the ridge is forecast to weaken as a trough approaches from the west. The weakening of the ridge should allow Bolaven to turn to the northwest.

Forecast Track (NOT OFFICIAL!)

The important aspect in the forecast track for Bolaven is the timing of the forecasted weakening of the ridge. Right now, computer models are in good agreement and takes Bolaven right into Okinawa by Saturday evening as a very powerful typhoon. The official agencies, on the other hand, is staying south of the model forecasts and are keeping Bolaven south of Okinawa sparing the island from strong damaging winds. Our forecast track above is in between the said scenarios but is positioned much closer to Okinawa. By that time, Bolaven could be a Category 3 or even a Cat 4 typhoon. However, the cone of uncertainty still remains large as there could still be wobbles and abrupt changes in movement. Therefore, residents along Northern Luzon, Taiwan, Eastern China, and the Ryukyu Islands should continue to closely monitor the developments of Bolaven.

We'll have another update tomorrow. Stay safe!
Issued (0930 UTC) 530pm PhT 082112

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