By PDC’s Senior Weather
Specialist Glenn James
The Pacific Disaster Center’s (PDC Global) Sunday, October 1, 2023, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas
Current Tropical Cyclones:
Tropical Cyclone 14W (Koinu)…is located approximately 489 NM south of Kadena AB
Northeast Pacific Ocean:
>>>South of Southwestern Mexico…
Shower and thunderstorm activity has increased since yesterday in association with a tropical wave located several hundred miles south of the coast of southern Mexico.
Environmental conditions are expected to be favorable for development of this system during the next several days, and a tropical depression is likely to form during the middle part of this week while it moves generally northwestward.
* Formation chance through 48 hours…medium…40 percent
* Formation chance through 7 days…high…80 percent
Central North Pacific:
There are no tropical cyclones, nor any areas of disturbed weather under investigation by the CPHC at the time of this writing.
Western Pacific, Indian Ocean and adjacent Seas:
Tropical Cyclone 14W Koinu
According to the JTWC Warning number 9…
Sustained winds were 75 knots…with gusts to near 90 knots
Animated enhanced infrared satellite imagery depicts a symmetric typhoon strength circulation with a transient 15 NM eye that is being obscured by recent flaring convection. Microwave images reveal an improving eye with building deep convective banding in all quadrants. A fortuitous scatterometry pass reveals an expansive and more symmetric wind field that still slightly favors the southern semicircle.
TY 14W (Koinu) has continued to rapidly intensify over the past 6 hours and is forecast to continue tracking northwestward under the steering influence of the ridge to the northeast. As the ridge continues to build and migrate westward, this results in a gradual westward arc toward the southern tip of Taiwan.
In terms of intensity, 14W will rapidly surge to around 100 knots by 24 hours, fueled by warm sea surface temperatures, low vertical wind shear and improving outflow aloft. Near 60 hours, 14W is forecast to reach its peak intensity of 110 knots and possibly higher before vertical wind shear increases and favorable outflow is lost.
The system is forecast to make landfall over southern Taiwan near 110 knots and proceed westward gradually weakening through the forecast period. It is important to note that if the ridge to the northeast builds up more rapidly or extends poleward of 14W as some models have recently indicated, this would cause a more dramatic westward course change, keeping the system over open waters and more importantly away from the Taiwanese mountain range, all of which could allow for additional intensification through the forecast period.