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Posted by Webmaster (Michael Padua) on October 8, 2006, 11:36 pm
Message modified by board administrator May 4, 2011, 6:04 pm
I was dismayed about PAGASA's article on their puzzlement of Milenyo.
Here are my answers on why MILENYO/XANGSANE rapidly intensified upon crossing Albay Gulf and not quickly losing strength while crossing Southern Luzon:
(1) The warm Sea Surface Temperatures (SSTs) present along the Philippine Sea, Sibuyan Sea and especially along the Albay-Lagonoy Gulf & San Bernardino Strait - which for my analysis are "pump-up" areas for typhoons passing by. Sea surface temperatures during the time the typhoon passed by ranges from 29 to 30 degrees celsius. Remember, that Typhoons get their fuel/energy from warm ssts (wam moist air) of at least 26 deg C.
(2) The very Low Vertical Wind Shear, a.k.a. Upper-Level Winds (winds blowing from 10,000 to 50,000 feet above sea level) over Southern Luzon-Northern Visayas Area. Wind Shear conditions can determine if a Typhoon can strengthen or not. Since a typhoon can reach a height of 50,000 ft., a strong vertical wind shear can stall the intensification process of a Typhoon and eventually weaken them. It's like placing a cone filled with ice cream infront of a blowing electric fan. While weaker shear, like the one during Milenyo's presence which is only about 9 km/hr can make the typhoon become more powerful.
(3) The topographic landscapes of Southern Luzon and Visayan Islands. One must know that the topography of Samar & Bicol are mostly flat except for some mountains which has no direct effects on typhoons, especially when it is moving fast. Take note that Milenyo has accelerated from 9 to about 20 km/hr, also the "archipelagic" nature of the Philippines, in which there are still pockets of warm ssts where typhoons can get fuel. e.g., Sibuyan Sea, Lamon Bay, Ragay Gulf.
(4) The Enhanced phase of the Madden-Julian Oscillation (MJO). One must know that the enhanced phase of MJO, can contribute further to the development of typhoons.
Here's a short definition of MJO taken from Wikipedia.org:
"The Madden-Julian Oscillation (MJO) is an equatorial traveling pattern of anomalous rainfall. The MJO is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean.
The wet phase of enhanced convection and precipitation is followed by a dry phase where convection is suppressed. Each cycle lasts approximately 30-60 days.
There is evidence that the MJO modulates this activity (particularly for the strongest storms) by providing a large-scale environment that is favorable (or unfavorable) for development. The strongest tropical cyclones tend to develop when the MJO favors enhanced precipitation. As the MJO progresses eastward, the favored region for tropical cyclone activity also shifts eastward from the western Pacific to the eastern Pacific and finally to the Atlantic basin."
(5) Other meteorological factors which can only be understood in the scientific community (eg. Dual Outflows, Nearby presence of TUTT).
Here are similar examples of Typhoon undergoing similar scenarios in the past:
*Super Typhoon SISANG (Nina) - Nov 26, 1987
*Typhoon SALING (Dan) - Oct 9, 1989
*Typhoon BEBENG (Vera) - July 14, 1983
The Albay-Lagonoy Gulf Area - must be studied thoroughly as it may be one of the most "pump-up" areas for Tropical Cyclones during the height of the Typhoon Seasons. This is similar to that of the Gulf Stream of the United States.
Take note: The waters of the Albay-Lagonoy Gulf Area are warm enough to fuel typhoons due to the north equatorial ocean current that moves across the Western Pacific Ocean and piles up warm SSTs over the area.
The above factors were confirmed by my good friend, Major Roger T. Edson, one of the leading, retired Joint Typhoon Warning Center (JTWC) forecasters of the US Air Force/Navy. He's now the Science and Operations Officer at the US National Weather Office in Guam.
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