Monday, August 22, 2011

Tropical Update ("Mina")

A Tropical Cyclone Formation Alert remains in effect for Invest 96W which is already a tropical depression according to JMA and PAGASA.

Invest 96W or Tropical Depression Mina was last located approximately 460km ENE of Virac, Catanduanes. Maximum winds remain around 40kph. 96W has been moving slowly north northwestward. Latest visual satellite imagery depicts a system that is still largely unorganized with most convection displaced west of the circulation center.

VIS image from NRLMRY

Invest 96W remains in an area of weak to moderate wind shear although that has been decreasing over the past 6 hours. Ouflow remains good, helping the system to ventilate. As mentioned at the top, a TCFA remains hoisted so there is still HIGH chance for 96W to fully develop into a tropical depression within the next 24 hours.

The forecast for 96W is for it to move northeastward in the coming days, totally avoiding a landfall in the Philippines. It will enhance rainshowers throughout the country though especially on the Eastern Seaboard. Likewise, as it continues to strengthen, it will also begin to enhance the SW Monsoon once again bringing widespread precipitation especially across Western Luzon and Visayas.

Moving on to the other system, Invest 95W remains very weak and undeveloped as it drifts near the Iwo To islands well south of Japan. The low-level circulation center remains fully exposed as wind shear continues to be high (around 30kts). JTWC still giving it a "MEDIUM" chance for development while JMA is still classifying it as a weak TD.

Tropical Forecast

There are still a lot of uncertainties with regards to the forecast for the tropics. Based on latest data, I do think 96W will develop into a tropical storm within 2 to 4 days. What is tricky here is the solutions from numerous computer models of two circulations developing in the Pacific this week: Invest 96W and another near Guam. I don't really think 95W will develop into anything significant. The monsoon trough situated near the Marianas will be the likely origin of another tropical system.If we do get two systems this week, there is a good chance of direct cyclone interaction or Fujiwhara effect between this two systems, making the forecast very uncertain. What is looking more likely, though, is that Okinawa could see some tropical storm conditions this weekend. Again, this is still all up in the air and always stay tuned right here for the latest updates and forecasts.

We will have our next Tropical Update by 5am tomorrow (PhT).
Issued (0830 UTC) 430pm PhT 082211

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