Tropical Storm Etau

[Somerset Squall]

TD 10 has formed, located several hundred miles south of Tokyo, Japan. The system has slowly been getting better organised over the last few hours, but the circulation is quite weak still and is only providing winds of 30kts. Convection is loosely wrapped around the centre, but 10W is showing little signs of definitive banding as yet. Shear is low, waters are warm and 10W is managing to display some fair to good equatorward outflow at the moment, as evidenced on latest satellite imagery, so the upshot of this is there should be at least some slow intensification over the next day or so. 10W will recurve northeastwards as it heads into the mid-lattitude westerlies, which will bring the cyclone very near to the south coast of Japan. As the system pushes northeastwards, it will encounter increasingly unfavourable wind shear and cooler waters which will weaken the system and induce extratropical transition. This shouldn't be for at least the next 48hrs though, so 10W has time to become a moderate tropical storm.

[Cookie]

busy busy

[Somerset Squall]

Indeed it is Cookie, and as that image says, much more typical for the West Pacific in August.

10W is struggling, and intensity has been reduced to 25kts. Morakot to it's west is definitely something to do with this, as it seems the much larger storm is not only robbing the environment of moisture but also restricting 10W's outflow. 10W should begin to strengthen as it nears warmer waters near the coast of Japan and puts some distance between itself and Morakot. JTWC is forecasting a peak of 35kts at this point so Japan is likely to see some rough conditions in the next day or so but nothing horrific unless 10W intensifies more than expected. Shortly after attaining storm status, 10W will begin extratropical transition as it accelerates northeastwards into colder waters.

[Cookie]

this image from weather underground sums up what you're saying

[Somerset Squall]

JMA have upgraded the depression to Tropical Storm Etau with winds of 35kts, meanwhile JTWC are still maintaining it as a tropical depression, albeit now at 30kts. Etau is a small storm (especially in comparison to Morakot!), and as Morakot is now weakening inland, Etau should be able to continue intensifying from this point forward. Convection is exploding over the LLC now which probably prompted JMA to upgrade, and I expect JTWC to soon follow suit. Etau is currently pushing northwards towards Japan, and probably has another 36hrs in which to strengthen. Etau could become a strong tropical storm (I'm thinking 55-60kts now as Morakot is having less of an influence) and brush very near the coast or even make landfall so there is a little cause for concern here. Japan have done pretty well to escape so far but I think it's pretty certain they will have a visit from Etau over the next day or so.

[Somerset Squall]

Etau has been upgraded to a tropical storm by JTWC. The small storm is moving northwards into a region of warmer waters, and also away from the weakening TS Morakot to the west, which should allow Etau to develop some outflow. The small storm is forecast to strengthen as the environment becomes more favourable, before racing northeastwards over cooler waters and beginning extratropical transition. Japan need to monitor Etau as the storm draws nearer.

[Cookie]

I tryed to get the thread title changed but I didn't put the full title.

[Ross B]

Fixed it for you mate (If it's right now? )

[Cookie]

yup thanks very much mate

[Somerset Squall]

Etau has fluctuated between storm and depression status over the last 12hrs with no clear intensification trend. The system is beginning the turn to the northeast around the northwestern periphery of a subtropical steering ridge anchored to the east. Waters remain warm and shear low for the next 24hrs, so Etau still has the chance to become a little stronger than the current intensity of 35kts, though not as high as I originally thought. Beyond this, shear will increase and waters cool on the increasingly speedy northeasterly heading, which will kick start extratropical transition, which is forecast to be complete in 48hrs time.

[Cookie]

more sad news from another country

http://news.xinhuanet.com/english/2009-08/10/content_11857243.htm

[Cookie]

looking better tonight

[Somerset Squall]

Etau is moving due east along the northern periphery of a subtropical steering ridge to the south of the storm. This is keeping the 35kt storm right on the northern extent of the warm waters, which is fuelling renewed convection over the still fairly well defined LLC. Etau is expected to eventually swing to the northeast as the ridge re-orientates itself to the southeast, blocking any direct eastward movement. This will soon put Etau over much colder waters which will induce extratropical transition.

[Somerset Squall]

Etau is rapidly becoming extratropical. The windfield is expanding and cold air is penetrating the core. As waters are significantly cooler now and shear higher, Etau will complete extratropical transition soon and will move into the open North Pacific as an extratropical storm.

[Cookie]

yup going down now fast.