west pacific Tropical Storm Toraji

[Somerset Squall]

The fifteenth tropical depression of the season has formed roughly 150 miles west of Okinawa, and northeast of Taiwan. 15W has winds of 25kts and some deep convection over an elongated LLC. The depression is currently in an area of low shear and marginal sea temps. 15W is forecast to head northeastwards then north as a ridge builds to the east. This will take the depression west of Japan into much cooler water, initiating extratropical transition. Thereafter, 15W will impact Japan as an extratropical depression.

Edited September 1, 2013 by Somerset Squall

[Somerset Squall]

JMA has upgraded the depression to Tropical Storm Toraji, with winds now at 35kts. Toraji has shown some improvement in organisation over the last few hours with convective banding features forming about the LLCC. Toraji doesn't have long to strengthen, and probably won't get above a moderate strength tropical storm before it reaches cooler water.

[Somerset Squall]

Toraji has strengthened over the last 24 hours, and is now a 50kt tropical storm. Convection continues to build over the LLCC, and banding features are becoming more prominant. Toraji is tracking slowly northeastwards towards southwest Japan. This motion is expected to persist, but could slow even more as steering influences become weak. Toraji could dissipate over Japan instead of moving northwards into the Sea Of Japan before beoming extratropical. Very heavy rains will continue spreading northeast through western and central Japan as Toraji closes in, with flooding a likelihood.

[Somerset Squall]

Strong southwesterly shear and cold air intrusion have initiated extratropical transition as Toraji nears Japan. Winds are down slightly to 45kts. Toraji will make landfall soon whilst completing extratropical transition. The storm's track has shifted a little further south too, meaning that Toraji's extratropical remnant will move up the spine of Japan rather than to the north. Rains will continue for a while yet, and spread to the rest of Japan with the continued northeasterly motion of the storm.

[Somerset Squall]

Toraji has become extratropical. The centre of the storm has elongated and there is no deep convection over the centre of the storm. Convection continues to shear well northeast of it, causing heavy rains to Central Japan. Extratropical Toraji will continue northeastwards, bringing further heavy rains to the rest of Japan.

[Coast]

 

 

A visible image of Tropical Storm Toraji was captured on Sept. 3 at 02:10 UTC/Sept. 2 at 10:10 p.m. is it continued moving north past eastern China and approached southern Japan. The image was taken by the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA's Terra satellite. The image showed strong thunderstorms wrapped around the center of the tropical storm. Bands of thunderstorms wrapping into the center from the north extended over Kyushu. Kyushu is the third largest island of Japan and is farthest southwest of Japan's four main islands.

 

At 1500 UTC/11 a.m. EDT on Monday, Sept. 2, Toraji had maximum sustained winds near 35 knots/40 mph/64 kph, so it was a minimal tropical storm. It was located about 100 miles northwest of Kadena Air Base, Okinawa, near 27.7 north and 126.5 west. Toraji was generating 13-foot/3.9-meter-high seas. That day, infrared satellite data from the MODIS instrument aboard NASA's Aqua satellite showed strong bands of thunderstorms wrapping around the southeastern and eastern quadrant of the storm, and spinning into the low-level center of circulation. Aqua passed over Toraji on Sept. 2 at 1328 UTC/9:28 a.m. EDT.

 

By Monday, Sept. 3 at 1500 UTC/11 a.m. EDT, Toraji's maximum sustained winds increased to 50 knots/57.5 mph/92.6 kph. The strongest winds are in the northeastern quadrant of the storm. Toraji moved closed to Kyushu and was centered near 30.5 north and 129.3 east, about 172 nautical miles/198 miles/318 km south-southwest of Sasebo, Japan. Toraji is moving to the northeast at 9 knots/10.3 mph/16.6 kph.

 

Wind shear has increased from the southwest today, Sept. 3. A deep layered mid-latitude trough (elongated area of low pressure) located over the Yellow Sea has created strong vertical wind shear. Winds are blowing from the southwest at up to 30 knots/34.5 mph/55.5 kph Toraji is now expected to make landfall in Kyushu and move back over open waters in the Sea of Japan where it is expected to parallel the western coast of Japan. It is expected to begin interacting with mid-level westerly winds and the Baroclinic Zone and become extra-tropical later today.

 

According to NOAA, the Baroclinic Zone is a region in which a temperature gradient exists on a constant pressure surface. Baroclinic zones are favored areas for strengthening and weakening systems; barotropic systems, on the other hand, do not exhibit significant changes in intensity. Also, wind shear is characteristic of a baroclinic zone, and wind shear can tear tropical cyclones apart.

Between the increased wind shear from the southwest and the interaction with the land (Kyushu), Tropical Storm Toraji is not expected to intensify before making landfall

 

 

 

http://phys.org/news/2013-09-nasa-satellite-tropical-storm-toraji.html#jCp