Tropical Cyclone 11P (Osai) / Tropical Cyclone 12P / Remnants of 10P
Thursday, February 8, 2024

Current Snapshot

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By PDC’s Senior Weather
Specialist Glenn James

The Pacific Disaster Center’s (PDC Global) Thursday, February 8, 2024, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone 12P…is located approximately 202 NM west-northwest of Port Vila, Vanuatu


Northeast Pacific Ocean:

The North Pacific hurricane season officially ended on November 30, 2023. Routine issuance of the Tropical Weather Outlook will resume on May 15, 2024. During the off-season, Special Tropical Weather Outlooks will be issued as conditions warrant.

The eastern Pacific basin hurricane season was above normal, with 17 named storms, of which 10 were hurricanes and eight of those major hurricanes.

From August 16 to 21, Tropical Storm Hilary brought widespread heavy rainfall and flooding to Southern California, with some areas receiving up to 600% of their normal August rainfall. Hilary resulted in the first ever issuance of Tropical Storm Watches and Warnings for the Southern California coastline by NOAA’s National Hurricane Center. In addition, the Center distributed key hazard focused messages for Hilary in Spanish through the agency’s new language translation project.

Hurricane Otis made landfall near Acapulco, Mexico, on October 25 as a category-5 hurricane, with sustained winds of 165 mph. Otis holds the record as the strongest land falling hurricane in the eastern Pacific, after undergoing rapid intensification in which wind speeds increased by 115 mph in 24 hours.

Central North Pacific:

The central North Pacific hurricane season officially ended on November 30, 2023. Routine issuance of the Tropical Weather Outlook will resume on June 1, 2024. During the off-season, Special Tropical Weather Outlooks will be issued as conditions warrant.

The central Pacific basin had a near-normal season with four tropical systems traversing the basin.

Hurricane Dora, a category-4 storm, passed south of Hawaii in early August, marking the first major hurricane in the central Pacific basin since 2020. The strong gradient between a high pressure system to the north and Dora to the south was a contributing factor to the wind-driven, fast-moving wildfires in Hawaii.


Western Pacific, Indian Ocean and adjacent Seas:

Southwestern Pacific Ocean…

Tropical Cyclone 12P

According to the JTWC warning number 5, sustained winds are 35 knots…with gusts to near 45 knots.

Tropical cyclone 12P continues to struggle against persistent west-northwesterly shear and so far has failed to build a vertically aligned vortex. The latest animated enhanced infrared satellite imagery depicts a sheared system, with an elongated and partially exposed low level circulation center (llcc), displaced to the northwest of persistent deep convection. If anything, the llcc has become more elongated and stretched out over the past six hours. A microwave pass suggests there may be two centers of rotation or vorticity within the elongated circulation center.

Overall, the environment can be characterized as marginally favorable at best, with the strong poleward outflow and warm sea surface temperatures only weakly offsetting the other negative factors noted above. The system remains moving southwest along the southern side of a strong ridge to the north.

TC 12P will continue to track east-southeastward through the majority of the forecast period, along the southern side of the ridge entrenched to the north. The system will begin to slow down after 72 hours as the ridge recedes eastward and the system moves into a weak steering environment, trapped between competing steering influences to the north and south. In the near-term, as long as the vortex remains misaligned and the llcc remains highly elongated, there is little chance of intensification and the system may in fact weaken slightly in the next 12 hours.

The forecast calls for the low-level wind field to maintain at 40 knots through 24 hours, primarily driven by the influence of a low-level westerly wind burst which will push elevated winds and vorticity into the system from the north. Due to the influx of dry air and persistent northwest shear, the vortex is likely to remain misaligned and convection will remain sheared to the southeast for the most part.

After 24 hours, shear is anticipated to weaken slightly, which should allow for a brief period of intensification to 45 knots, before shear picks up once again and drives a slow but steady weakening trend through the remainder of the forecast period. As it weakens to minimal tropical storm strength by 120 hours, TC 12P becomes quasi-stationary by 120 hours under the competing low-level steering influences.


>>> There’s an area of disturbed weather being referred to as Remnants of 10P…which is located approximately 160 NM southeast of Papeete, Tahiti.

The system is currently classified as a subtropical cyclone, generally characterized as having both tropical and mid-latitude cyclone features.

Animated visible satellite imagery depicts a warm core assymetric system with convection that has been sheared to the southeast of a partially exposed low level circulation (llc), typical of a subtropical system. Winds of up to 35 knots are over the southern periphery of the llc.

Environmental analysis reveals unfavorable conditions for tropical transition defined by a deep layer of dry air being advected over the circulation, strong westerlies aloft, and high (greater than 30 knot) vertical wind shear.

Global models are in agreement that the remnants of TC 10P will track southeastward with a broad and asymmetric wind field.

Maximum sustained surface winds are estimated at 33 to 37 knots.

The potential for the development of a significant tropical cyclone within the next 24 hours is low.