Cyclone Sean Shows Signs of Weakening After Peaking in Intensity

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Severe Tropical Cyclone Sean, which posed a significant threat to Australian ports, has likely reached its peak intensity. Recent satellite imagery reveals early signs of weakening, as cloud top temperatures around the storm’s well-defined eye begin to warm. While still formidable, Sean’s diminishing strength offers some relief to coastal communities and shipping operations.

Data from infrared and microwave imagery confirms the storm’s center remains well-structured, with the radius of maximum winds approximately eight nautical miles. Interestingly, signs of a secondary eyewall formation have emerged, hinting at a possible eyewall replacement cycle. These cycles, while common in intense tropical cyclones, can temporarily stabilize or even slightly re-intensify a storm before leading to further weakening. Current estimates suggest Sean’s Maximum Potential Energy Reduction Capability (MPERC) has peaked at around 45%.

Experts analyzing the cyclone’s development have reported Dvorak Technique measurements indicating a Current Intensity (CI) of 6.0. This aligns with objective data placing Sean’s sustained winds between 95 and 115 knots. Notably, an AMSR2 pass earlier today recorded slightly lower intensities, highlighting the variability in such dynamic systems.

Forecast models remain consistent, predicting Sean’s track will continue southwest, skirting the western periphery of a mid-level ridge before veering southward on Wednesday. Despite favorable upper-level conditions, including low wind shear and strong outflow, the cyclone is moving over cooler waters with sea surface temperatures (SSTs) around 28°C. Cooler SSTs are expected to accelerate the weakening trend, especially as dry air and increased wind shear compound the effects.

For now, Sean retains its Category 4 status but is expected to downgrade significantly within the next 24 to 36 hours. By Thursday, the cyclone is anticipated to lose its tropical cyclone intensity entirely. However, gales southwest of its center, fueled by synoptic southeasterly flows, could persist and disrupt maritime activities in the region.

This development has implications for Australian ports, which had been on high alert for potential disruptions. While the worst seems to be over, careful monitoring remains essential as lingering winds and waves could still pose localized hazards to shipping and logistics.

^{Source: gov.au}