Friday, August 19, 2011

Tropical Update

We have some important updates today. A low pressure area has now formed near the Marianas: Invest 95W. The cluster of convection is located northeast of Guam (700km). The Visual Satellite image shows a fairly robust system with good mid-level presentation and with a slightly elongated low-level circulation. IR image shows convective activity is looking good as well with some "hot tower" firing off near the center.

Invest 95W is in a very good environment with weak wind shear, good outflow, and high sea surface temperatures which should allow it to slowly develop over the next few days. JTWC is currently rating this LPA as "LOW". If it does develop, it should move generally to the north towards Southern Japan around the western periphery of the Subtropical Ridge centered over the North Pacific.

Computer models are kinda split right now (we'll discuss the models later in this post) in terms of 95W's development but the latest trends suggest we could be seeing our next tropical system in the next 3 to 5 days.

Image below (NRLMRY) shows the Western Pacific Basin and the location of Invest 95W, as well as the ITCZ.

SW Monsoon still affecting the Indochina dropping 50-150mm of rain in 24 hours. The Philippines, on the other hand, will experience scattered showers with isolated pockets of heavy rain. Radar images from Subic and Hinatuan (PAGASA) showing scattered rain showers. A weak disturbance just east of Luzon is also enhancing some precipitation in the Northern Luzon area. Expect light to moderate amounts of rain for the next 24 to 36 hours (50-100mm).

Now into the computer models:

The latest global model suite (00z) shows 2 scenarios as we head into next week; discussed below (image from NRLMRY):

The first one (Red) is supported by GFS, the CMC, NOGAPS (somewhat), and the FIM (an experimental model) - shows a cyclone forming near the Marianas (could be 95W) moving north towards S. Japan with another cyclone developing near that same area and moving generally northward as well.

The second one (Blue) is being shown by the ECMWF, NOGAPS, and UKMET... they limit the development of 95W and instead focus on another vortex near Yap, bringing it towards the Taiwan-Okinawa area. Euro and NOGAPS also shows a potential cyclone development north of CNMI at the end of their respective runs.

Whatever scenario pans out, looks like the models are indeed painting a more active W. Pacific by next week.
Issued (0830 UTC) 430pm PhT 081911

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