Current Snapshot

The Pacific Disaster Center’s (PDC Global) Wednesday, September 4, 2024, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone 12W (Yagi)…is located approximately 220 NM south-southeast of Hong Kong

Tropical Cyclone 13W…is located approximately 431 NM southeast of Yokosuka, Japan

Northeast Pacific Ocean: There are no Tropical Cyclones…nor any areas of disturbed weather under investigation by the National Hurricane Center (NHC)

Central Pacific Ocean: There are no Tropical Cyclones…nor any areas of disturbed weather under investigation by the Central Pacific Hurricane Center (CPHC)

Western Pacific, Indian Ocean, and adjacent Seas:

Tropical Cyclone 12W (Yagi)

According to the JTWC Warning number 14, sustained winds are 120 knots with gusts to near 145 knots

Animated enhanced infrared satellite imagery depicts a strong typhoon with an eye feature that has a characteristic trochoidal wobble as the system has undergone rapid intensification over the last six hours. Upper-level outflow remains strong and equatorward into a region of upper-level diffluence to the southwest.

Typhoon 12W is forecast to track west-northwestward while under the steering influence of a ridge to the north. By 48 hours, the system is expected to pass over northern Hainan and the Luichow Peninsula before entering the Gulf of Tonkin and making landfall over northern Vietnam.

The current trend of rapid intensification is forecast to continue for the next 24 hours to a peak intensity of 135 knots while remaining in a highly favorable environment comprised of low vertical wind shear, warm sea surface temperatures, and strong upper-level outflow. High ocean heat content in the warm tub of the South China Sea is what will take the environment over the edge to allow the system to rapidly
intensify.

Weakening will commence as the system interacts with the Luichow Peninsula and Hainan and continue after making landfall in northern Vietnam. The northern extent of the Annamite mountain range will cause the vortex to shallow out as it passes over peaks above 5,000 feet high and fully dissipate by 96 hours.

Tropical Cyclone 13W

According to the JTWC Warning number 4, sustained winds are 25 knots with gusts to near 35 knots

Animated enhanced infrared satellite imagery depicts a consolidating yet struggling tropical depression with flaring convection obscuring the low-level circulation center (llcc). Water vapor imagery reveals weak radial outflow that is disturbed by a nearby upper-level cyclone to the southwest. The cyclone also introduces dry air to the circulation wrapping around the southern periphery from the west.

TD 13W is forecast to round the axis of the ridge to the northeast for the next 24 hours before continuing on a northwestward track through the end of the forecast period. The environment will remain marginally favorable for intensification with an unfavorable upper-level environment that will be induced by a nearby short-wave trough that approaches from the northwest before the system becomes embedded between tau 48-72.

The encroaching trough will initiate extra-tropical transition, coupled with cool sea surface temperatures that TD 13W will pass over. Baroclinic forcing will maintain the intensity of 30 knots through the end of extra-tropical transition. It is possible that the upper-level trough may approach sooner than reflected in the forecast, thereby initiating extra-tropical transition earlier.