Monday, December 12, 2011

Tropical Depression 26W Update #1

Invest 94W has just been upgraded by the Joint Typhoon Warning Center into a Tropical Depression. The center of 26W was last located approximately 450km west of Southern Palawan or about 750km east of Ho Chi Minh in Vietnam. Maximum sustained winds are estimated to be around 45kph gusting to 65kph. TD 26W is moving westward at 15kph.

Significant improvements in the upper-air environment in the past 24 hours have really helped the recent organization of 26W. Wind shear in the area is currently sitting at around 15 to 20 knots with sea surface temperatures somewhat favorable. Dry air from the north easterlies (monsoon) are being offset by a surge of south westerlies that JTWC is attributing to a MJO event. These conditions should help 26W strengthen a little bit or at least maintain its current intensity for another 24 to 48 hours. Computer models bring 26W westward and eventually southwestward under the ridge and could begin to affect Southern Vietnam by Tuesday.

Satellite image below (from NRLMRY) shows the partially exposed low-level circulation center as well as the blow-up of strong convection (brighter white clouds) west and northwest of the circulation. The eastern side of the storm is "empty" due to the presence of shear.

Meanwhile, nother area of low-pressure was spotted in the middle of the Western Pacific. Invest 95W is located about 700km west of Pohnpei in Micronesia. Cyclonic turning is evident on the satellite loop as well as a recent microwave image. 95W is located in an area of light to moderate wind shear (10 to 20kts) with favorable sea temperatures. Computer models are not showing any development and most of them keep it as a weak tropical wave moving westward. Nevertheless, we'll continue to watch this little system as it could definitely evolve into something more than a LPA.

IR image from NRLMRY

Issued (09 UTC) 5pm PhT 121211

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