Tropical Cyclone 21S (Olga) / Invest 97P
Tuesday, April 9, 2024

Current Snapshot

For all the latest updates visit: DisasterAWARE

By PDC’s Senior Weather
Specialist Glenn James

The Pacific Disaster Center’s (PDC Global) Tuesday, April 9, 2024, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone 21S (Olga)…is located approximately 233 NM north-northeast of Learmonth, Australia


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

South Indian Ocean…

Tropical Cyclone 21S (Olga)

According to the JTWC warning number 18, sustained winds are 35 knots…with gusts to near 45 knots

Animated enhanced infrared satellite imagery depicts tropical cyclone 21S (Olga) with a fully exposed low-level circulation center as strong vertical wind shear of 30-35 knots continues to bear down on the vortex. The recent flare-up of convection near the center has already been pushed off to the southeast along the strong shear vector.

Moderate poleward outflow is dampened as the system approaches the subtropical jet stream to the south, mitigating upper-level divergence. Sea surface temperatures remain favorable. The cyclone appears to have begun to stall and drift over the last six hours as the low-level steering mechanism has weakened as the structure of the cyclone weakens.

TC 21S is forecast to continue on a southwestward track over the next 48 hours while driven along the westward periphery of a low-level ridge over the western portion of the Australian continent. However, minor deviations in the orientation of the ridge could result in a track closer to the Exmouth peninsula or further out to sea.

The intensity is forecast to continue to weaken to full dissipation through 48 hours while overrun by increasingly strong vertical wind shear, which is expected to reach over 75 knots. Despite the dissipation, the strongest winds will persist in the southern hemisphere of the system, skirting the coast of northwest Australia as the system passes offshore.

Southwest Pacific Ocean…

>>> According to the JTWC, there’s an area of disturbed weather under investigation, being referred to as the Invest 97P…which is located approximately 373 NM east-southeast of Port Moresby.

Animated multi-spectral satellite imagery and a microwave image depict consolidating convection to the northwestern periphery of the low
level circulation center.

Environmental analysis shows a favorable environment for development with warm sea surface temperatures, low (5-10 knot) vertical wind shear, and strong equatorward outflow aloft. however, dry air to the southwest of the system may be a limiting factor.

Global ensemble models are in good agreement that 97P will turn west and travel just south of Papau, New Guinea. The deterministic GFS and ECMWF models show some development over the next 24 to 48 hours.

Maximum sustained surface winds are estimated at 23 to 23 knots.

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