Tropical Storm Banyan

[Somerset Squall]

The twenty-third tropical depression of the season has formed around 750 miles east-southeast of Manila, Philippines. Convection is slowly increasing and consolidating about the LLC. Intensity is 30kts. 23W is expected to intensify under low shear and warm sea temps. The depression is expected to become a tropical storm before making landfall in northern Mindanao. 23W should then continue moving northwestwards along the southwestern periphery of a subtropical steering ridge and emerge into the South China Sea (SCS) west of Luzon. Weakening will occur over the islands of the southern Philippines but conditions are favourable for re-intensification once in the SCS.

[Somerset Squall]

23W has strengthened into Tropical Storm Banyan, with intensity now at 35kts. The storm is making landfall across the southern Philippino island chain. Banyan will weaken back to a tropical depression as a result, before re-strengthening over the South China Sea. Final landfall is uncertain, but Hainan Island and Vietnam are at risk yet again.

[Somerset Squall]

Banyan has suffered badly from the crossing of the Philippines and is only slowly recovering over the South China Sea as the upper level conditions have only been marginally conducive for intensification (low shear but poor poleward outflow). Banyan weakened to 25kts but intensity is now back up at 30kts. The depression has only shallow convection but should still strengthen over the next 24hrs or so as shear remains light and waters warm. Banyan will be entering waters upwelled by Nesat and Nalgae beyond this time, which will cause the intensity of Banyan to plateau. Ridging in South China is expected to eventually stop poleward progression of Banyan and instead drive the cyclone westwards towards landfall in Vietnam, currently progged to occur in about 4 days time.

[Cookie]

[Somerset Squall]

Banyan has not strengthened, and has instead degnerated into a remnant low. This is a prime example of how difficult wind shear is to predict. Shear rose dramatically over Banyan today due to an approaching trough. As the depression also wondered northwards over cooler sea temps, it lost convection and the LLC became ill defined due to the destructive force of the shear. Regeneration doesn't appear likely as the environment is not forecast to improve.