Tuesday, July 5, 2011

Tropical Update

An active monsoon trough continues to affect the Philippines. At the eastern end, east of the Philippines, is what looks to be a Monsoon Depression. Within this system are multiple circulations, right now we have two: Invests 94W and 98W. As the monsoon moves northward, so do the two invests. Right now, both disturbances are rated "LOW" chance by JTWC.

94W was last located approximately 500km east of Tuguegarao. ASCAT shows 30-40kph winds on the eastern side of the circulation. This LPA is in a strong wind shear environment. Furthermore, computer models have backed away in showing a cyclone formation. The TUTT in the Philippine Sea has moved northeast is enhancing outflow on 94W (the system being on the southwestern side of the cell). Due to size and not so impressive convective activity, we expect development will be slow. It still has a chance though, especially if wind shear relaxes in the area.

98W, meanwhile, was last located 480m east of Manila. The system is also having spotty convection although a recent AMSRE pass seems to show a curved banding, not sure if it is associated with a developing center. ASCAT did not pick up the exact location of the LPA although reports from Luzon indicate a weak circulation off of Catanduanes, also latest METAR from RPLL (NAIA) of northwesterly winds and 1004mb pressure suggest that the LPA might just be nearby Luzon. Computer models slowly lift the storm northward, with some forecasting it to be a weak cyclone affecting Taiwan this weekend or early next week.

With the active monsoon, expect cloudy skies with increased chance for rainfall to continue this week. As the monsoon trough lifts northward, and as a surface ridge builds itself east of Mindanao, expect clearing weather for places in Southern Philippines.

Moving on, a weak disturbance was spotted in Eastern Micronesia, now moving west of Chuuk (well southeast of Guam). Latest Area Forecast Discussion (AFD) by NOAA-GUAM, notes the circulation associated with the high clouds. They are also noting how computer models are forecasting this to continue developing in the coming days. Computer models are not picking this up yet, except CMC. NRLMRY is not putting this up as an invest either. With that said, the system still has a lot of ways to go so we will continue to watch.

Issued (08 UTC) 4pm PhT 070511

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