Thursday, July 7, 2011

Tropical Update

We are still monitoring 94W east of Taiwan while a new invest, 90W, has formed in the middle of the Pacific. 99W in South China Sea has dissipated.

A low-level circulation center exhibited by 94W was last spotted approximately 350km east of Taipei, Taiwan. The center is near Miyako Islands. Latest wind readings from JMA indicate the center has passed and is now just to the northwest of Miyako or northeast of Ishigaki. Southwesterly of around 20kph and northwesterly winds of around 15kph. Furthermore, readings from Taiwan indicate 1002-1004mb surface pressure. The center is exposed and is not showing any signs of improvement. An AMSRE 37Ghz image shows weak banding and IR image not showing any kind of convection associated with the low pressure area. JTWC is still rating this system as "Low". Vertical wind shear in the area continues to be high, around 20-30kts. Computer models, however, are still intent on developing a cyclone east of Taiwan. Now, it could be that the cyclone these models are showing is not 94W; it could be another LPA that will branch off of the monsoon trough still currently in the Philippines. Nevertheless, we will continue watching 94W for possible improvement today and into tomorrow.

Moving away from this area, 90W was spotted in the middle of West Pacific. This LPA is now moving west of Wake Islands. Computer models are actually in somewhat good agreement as to the eventual development of this LPA, with the EURO and CMC being the strongest and GFS not far behind in terms of intensity. Good news is that if this does develop, it will be far away from the Philippines or any other land mass, except for small islands dotting the Pacific. JTWC is not rating this yet. The area is in a moderate wind shear environment so expect slow development. Compared to 94W, it seems this LPA has a higher chance of becoming a cyclone in 2-3 days' time.

Going to back to the Philippines, the monsoon trough has weakened somewhat and most areas are actually reporting just cloudy skies. Still, be on the lookout for thunderstorms especially in the afternoon. Based on latest METAR reports, high chance of seeing thunderstorms are Zamboanga and Davao in Mindanao and Laoag in Northern Luzon. Southwesterly flow with winds of 10-20kph will continue to persist throughout the country.

Issued (0830 UTC) 430pm PhT 070711

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