By PDC’s Senior Weather
Specialist Glenn James
Tropical Cyclone 04W (Chaba) is located approximately 240 NM south of Hong Kong
Tropical Cyclone 05W (Aere) is located approximately 409 NM south-southeast of Kadena AB
Offshore of Southern Mexico:
A broad area of low pressure is located several hundred miles south-southwest of the southern tip of the Baja California peninsula is producing winds of gale-force.
Although the shower and thunderstorm activity associated with the system continues to show signs of organization, this afternoon’s satellite-derived wind data indicated that the system still lacks a well-defined
Environmental conditions are generally conducive for development and a tropical depression could still form during the next day or two before it reaches cooler waters Saturday while moving west-northwestward at 10 to 15 mph.
* Formation chance through 48 hours…medium…60 percent
* Formation chance through 5 days…medium…60 percent
>>> Northwest and Southwest Pacific Ocean, Indian Ocean, Arabian Sea
Tropical Cyclone 04W (Chaba)
According to the JTWC Warning number 6, sustained winds were 50 knots with gusts to near 65 knots.
Animated enhanced infrared satellite imagery depicts spiral bands of deep convection wrapping into a persistent deep convective cloud structure. A microwave image depicts formative convective banding in all quadrants with several additional convective bands to the south and west of the low level circulation.
TC 04W (Chaba) is forecast to track northwestward in a favorable environment before making landfall east of Luichow Peninsula.
Environmental conditions are forecast to remain favorable, characterized by warm sea surface temperatures, moderate divergence aloft and low-moderate vertical wind shear (9-16 knots) which will allow Chaba to reach a potential maximum intensity of 70 knots by 36 hours.
Between 36 and 48 hours Chaba will begin to interact with both the island of Hainan and eventually mainland China significantly impacting intensity as the system continues to track northwestward.
Between 48 and 96 hours TC 04W will steady up on an approximate north-northeastward track as it continues to succumb to the orographic impacts of southern China before finally dissipating near 120 hours.
Tropical Cyclone 05W (Aere)
According to the JTWC Warning number 3, sustained winds were 35 knots with gusts to near 45 knots.
Animated enhanced infrared satellite imagery depicts a cold dense overcast curving into and obscuring the low level circulation center.
TD 05W is forecast to track north-northwest under the steering influence of the subtropical ridge to the northeast.
Currently in a marginally favorable environment characterized by warm sea surface temperatures and moderate outflow aloft enhanced by the tutt cell to the northwest slightly offset by moderate vertical wind shear (20-25 knots).
This environment is forecast to steadily increase TD 05W through 36 hours, after which the system is forecast to pass over Okinawa and reach its peak intensity of 50 knots by 48 hours.
Between 48 and 72 hours, as the subtropical ridge is broken down by a passing mid-latitude trough the system will begin to track north-northwestward and eventually northward as significant amounts of dry air begin to entrain the system.
Through the remaining forecast period, as the system continues to approach the ridge axis, sea surface temperatures drop and significant dry air entrainment is forecast to begin dissipating 05W.
By 120 hours the system is forecast to be fully entrained by dry air and nearing full dissipation.