Current Snapshot
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By PDC’s Senior Weather
Specialist Glenn James

The Pacific Disaster Center’s (PDC Global) Tuesday, January 21, 2025, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas
Current Tropical Cyclones:
Tropical Cyclone 10S (Sean) is located approximately 489 NM southwest of Learmonth, Australia
Northeast Pacific Ocean: There are no Tropical Cyclones
The last regularly scheduled Tropical Cyclone Activity Report of the 2024 eastern North Pacific Hurricane Season has been issued. Routine issuance of this section of the PDC product will resume on May 15, 2025. During the off-season, Special Tropical Weather Outlooks will be issued as conditions warrant by the NHC.
Central Pacific Ocean: There are no Tropical Cyclones
The 2024 central North Pacific hurricane season has ended. As such, the final routine Tropical Cyclone Activity Report for the 2024 season has been issued. Routine issuance of this section of the PDC product will resume on June 1, 2025. During the off-season, Special Tropical Weather Outlooks will be issued as conditions warrant by the CPHC.
Western Pacific, Indian Ocean, and adjacent Seas:
South Indian Ocean
Tropical Cyclone 10S (Sean)
According to the JTWC Warning number 17, sustained winds are 45 knots, with gusts to near 55 knots
Tropical cyclone 10S (Sean) continues to steadily deteriorate as it approaches the subtropical ridge (str) axis far west of Shark Bay, Australia. Animated satellite imagery depicts a very small area of shallow convection and remnant cirrus debris obscuring the low level circulation center (llcc). The
image also shows shallow bands of stratocumulus clouds in well-defined low-level bands all along the western hemisphere of the circulation. A color-enhanced microwave image depicts well-defined, shallow banding features wrapping into a compact low level circulation center and all convection displaced
southeast of the center.
The environment continues to deteriorate. Cimss deep-layer shear is estimated as from the north at just five knots though GFS and EVMWF model-derived soundings tell a slightly different tale, with deep layer shear exceeding 15 knots from the west and mid-level shear pushing 25 knots. The depiction in the microwave imagery strongly suggests the model-derived shear estimates are more correct in this case. Sea surface temperatures are now cool as well, with these negative factors offsetting the robust poleward outflow.
TC 10S has yet to reach the str axis, as the track continues towards the southwest, though there are some signs in the most recent frames of imagery that the system is starting to slow down precipitously, a sign that it is reaching the ridge axis imminently. Regardless, it is anticipated that TC 10S will continue to slow down over the next 12 hours as it reaches and then rounds the ridge axis. By 24 hours, the system should be south of the axis and will begin to accelerate towards the southeast through the remainder of the forecast period. Now that the system has moved over cooler waters, the system has lost its energy source, and this is reflected in the fact that convective activity has completely collapsed over the last few hours.
Additionally, the influx of very dry air in the upper- to mid-levels of the atmosphere moving in from the west has started to smother the system from above, while moderate to strong westerly shear is tearing the vortex apart. All things considered; the system will likely be a remnant low-level vortex within the next 12 to 24 hours, rapidly taking on a more subtropical look as it continues poleward. The system is expected to rapidly weaken over the next 24 hours as it rounds the ridge, but then the pace of weakening will slow as the remnant vortex slowly spins down. The system is expected to dissipate below warning criteria no later than 48 hours while simultaneously undergoing extratropical transition.