Wednesday, July 6, 2011

Tropical Update

The monsoon trough moving northward continues to bring widely scattered showers across parts of the Philippines. A low pressure area, Invest 94W, continues to spin near Luzon while a new LPA, Invest 99W, was spotted in South China Sea. 98W has dissipated.

94W was last located approximately 180km northeast of Aparri, Cagayan. IR and VIS satellite imagery shows an area devoid of any vigorous development. The area, right now, is just too hostile it seems for TC development with wind shear still in the 20-30kt range. Some computer models do keep on showing a very weak circulation in the coming days, which will eventually impact either Taiwan or the Senkaku Islands (near Okinawa). CMC is the most aggressive in developing a storm. GFS shows the same scenario, albeit at a slower pace. Most models do show this "future" storm stalling east of Taiwan as the steering influences weaken around the area. Still rated "Low" by JTWC so will continue to keep an eye on it and the main thing keeping this systems from intensifying is the wind shear, so as I've said yesterday, if the wind shear relaxes we could see a cyclone form.

A new invest was spotted today. Invest 99W was located approximately 220km west of Laoag City. A recent AMSRE 37Ghz microwave image shows a weak low level curved banding while IR and VIS images show few cold cloud tops although seems to be mostly associated with the diurnal cycle. Not yet rated by the JTWC, and not being shown by the models yet. Environment is not that friendly either but we'll keep on watching.

As for the general weather, the monsoon trough continues to lift itself northward slowly bringing scattered showers with occasional heavy downpours. Recent METARS from Laoag, Clark, and Manila all indicate cloudy skies with thunderstorms. Partly to mostly cloudy skies in Cebu and Visayas although increased chance for precipitation. Weather has actually improved over much of Mindanao although the threat for afternoon thunderstorms still remain. Just watch for downpours that can certainly bring flash floods especially near bodies of water and urban areas such as Manila. Be mindful of landslides also in mountainous areas with very few big trees, as what we've seen in Bukidnon in Mindanao.

Long-range forecasts from computer models show the trough will not be moving anytime soon so we should expect this kind of weather to last until next week.

Meanwhile, a tropical disturbance not associated with the trough continues to move across Micronesia bringing scattered showers in the islands there. Wind shear is relatively low in this part of the Pacific although neither JTWC nor NRLMRY is rating this LPA just yet. Computer models are split over the eventual evolution of this system. As always, CMC leads of the pack in terms of intensity bringing northward near Guam in the coming days. Another area to look out so always keep it right here for latest daily updates!

Issued (0830 UTC) 430pm PhT 070611

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