Tropical Storm Vongfong

[Somerset Squall]

The twelth tropical cyclone of the 2008 West Pacific season has formed, to the south of Japan. Moderate shear, high ocean heat content and good outflow has allowed for this development. An upper level anticyclone will continue to provide an exhaust for 12W, which should allow for some intensification as the system pushes generally northwards. A northeastwards curve is expected but the timing of this is uncertain, and also crucial in regards to whether mainland Japan will recieve a visit from 12W or not.

Also worth noting is Tropical Depression 11W. I didn't make a thred about this one as it was forecast to remain a tropical depression, and it has done so. It's now dissipating over South Korea after forming yesterday, and is giving heavy rains here but it shouldn't cause much problem. Full dissipation will occur over land.

Image of 12W:

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Storm Alert issued at 14 Aug, 2008 18:00 GMT

Tropical Depression 12W is forecast to strike land to the following likelihood(s) at the given lead time(s):

Green Alert Country(s) or Province(s)

Japan

probability for TS is 35% in about 24 hours

Note that

Green Alert (Low) is TS to between 31% and 50% probability.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

[Somerset Squall]

12W has rapidly strengthened overnight, and has become Tropical Storm Vongfong, with an initial intensity of 45kts. An upper level anticyclone has shielded Vongfong from shear and also has provided goof outflow for the storm, which has allowed for this rapid intensification. Convection is fairly deep over the centre and banding features are becoming more impressive. However, time is running out for Vongfong, because in 24hrs, the anticyclone will move away exposing the storm to very strong shear and Vongfong will get caught in upper level westerlies which will cause the storm to begin extratropical transition. Vongfong will rapidly accelerate northeastwards just to the southeast of Japan and dissiapte as an extratropical system in cold waters and high shear. Vongfong could intensify a little more before this occurs, but it is unlikely to become a typhoon.

[Somerset Squall]

Vongfong peaked at 50kts earlier this afternoon, but has since weakened. The anticyclone is no longer shielding Vongfong from the shear, and the storm is also accelerating over cooler waters. Convection remains deep in a curved band stretching to the east and south of the LLC, but convection over the centre itself is less healthy than this morning, as the latest satellite image shows:

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Storm Alert issued at 15 Aug, 2008 6:00 GMT

Tropical Storm VONGFONG is forecast to strike land to the following likelihood(s) at the given lead time(s):

Green Alert Country(s) or Province(s)

Japan

probability for TS is 45% in about 24 hours

Note that

Green Alert (Low) is TS to between 31% and 50% probability.

TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

Edited August 15, 2008 by cookie

[Somerset Squall]

Vongfong is now extratropical. It looked better for a while yesterday but the storm finally succumbed to the strong shear and cold waters.