Tropical Storm Matmo

[Somerset Squall]

The fourth tropical cyclone of the West Pacific season has formed today, east of Manila, Phillipines. 04W is expected to strengthen in favourable conditions for the next 36 hours before shear increases due to the presence of a trough, and ocean heat content lowers on the brisk northeastwards track. 04W is expected to follow a roughly similar track to the second half of Rammasun's life, due to the same subtropical ridge to the east and the trough to the northwest. Interaction with the trough should induce extratropical transition by 48hrs which is expected to be completed by 72hrs.

Satellite image of the newly formed TD04W:

[Cookie]

Another storm to keep us going till the Atlantic season arrives

[Somerset Squall]

Doesn't look like it will last that long Cookie :o

TD04W hasn't strengthened at all overnight and the beginnings of extratropical transition (ET) are happening earlier than previously thought. The northern quadrant of the system is being sheared which is leaving the LLC partially exposed which is stopping any intensification. Cold, dry air is wrapping into the western quadrant of 04W which is initiating ET. ET is expected to be completed within the next 48hrs as 04W races east-northeastwards. JTWC expect a peak of 40kts with this system, so it may briefly make tropical storm strength.

[Somerset Squall]

Tropical Depression 04W has become a little better organised over the past 6 hours, and winds near the centre have justified it being upgraded to Tropical Storm Matmo. Matmo is not far off becoming extratropical though, with cold and dry air wrapping into Matmo's western quadrant, and shear remaining high. Matmo is expected to finish ET in 24hrs time as the storm continues to interact with the baroclinic zone.

New image of the recently upgraded Matmo:

Taken from NAVY/NRL

[Somerset Squall]

JTWC have issued thier final warning on Matmo, as it rapidly becomes an extratropical storm. There is very little deep convection associated with Matmo any more as the core becomes cold. Tracking looks to be a little further south than before so effects in Japan will probably be minimal, however it is possible that when Halong becomes extratropical it may be a lot nearer to Japan, anyway, that's for the Halong thread.

[Cookie]

It didn't last very long did it?!

[Somerset Squall]

It didn't last very long did it?!

It didn't, no. The northern half of the West Pacific basin has reletively cold waters still, and as Matmo formed quite far north it didn't have much time over sufficiently warm waters to be long lasting.