Tropical Cyclone 23S (Hidaya)
Friday, May 3, 2024

Current Snapshot

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By PDC’s Senior Weather
Specialist Glenn James

The Pacific Disaster Center’s (PDC Global) Friday, May 3, 2024, Tropical Cyclone Activity Report…for the Pacific Ocean, the Indian Ocean, and adjacent Seas

Current Tropical Cyclones:

Tropical Cyclone 23S (Hidaya)…is located approximately 110 NM southeast of Dar Es Salaam, Tanzania


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 23S (Hidaya)

According to the JTWC advisory number 6, sustained winds were 55 knots, with gusts to near 70 knots.

Tropical cyclone 23S (Hidaya) has set a new record, as the most intense TC in this region in the historical database, peaking at an estimated 80 knots earlier in the day. Rapidly increasing shear and an influx of dry air in the mid-levels means that the system will weaken from here forward.

Animated multi-spectral satellite imagery depicts a rapidly deteriorating structure, with the areal extent of the inner core quickly decreasing, especially on the eastern side, as dry air flows in from the north. The inner core remains well-defined with intense convection obscuring the low level circulation center (llcc), though the previously visible eye has now filled in completely. The last microwave image showed a well-defined low-level microwave eye feature, though the eyewall is clearly eroding from the north.

The latest cimss shear analysis indicates northerly deep-layer shear is ramping up, now estimated at 15 knots or higher. As mentioned, dry air is also flowing in from the north along the eastern side of the system, further eroding the inner core and inhibiting convection. Otherwise, environmental conditions are generally good, with moderate poleward outflow and warm sea surface temperatures, but these are just not enough to offset negative influence of the shear and dry air.

The previous forecast called for continued intensification, but this forecast calls for the opposite, resulting in a large change in the forecast intensity, particularly in the first 12 to 24 hours.

TC 23S has continued to track west-northwest over the past day, along the northeastern periphery of the deep-layer ridge centered over South Africa. The system is expected to maintain this general track motion through the next 24 hours, approaching a landfall along the coast of Tanzania south of Dar Es Salaam by 24 hours. As the system weakens rapidly, the steering flow becomes progressively shallower, where the ridge is oriented more north-south. The net effect will be for the system to turn more equatorward as it weakens.

The current forecast calls for the system to track very close to Dar Es Salaam and then remain inland as it dissipates. A faster rate of weakening could result in the system turning more sharply northward and tracking back out over water as it dissipates, as is suggested by some of the model guidance.

In terms of intensity, the system peaked at 80 knots, but is now starting to come down, albeit slowly as it is just beginning to feel the effects of increasing shear and dry air entrainment. Shear is expected to rapidly increase over the next 12 to 24 hours, which quickly erodes the vortex, as well as ushering in additional dry air. Add in the disruption of the low-level inflow due to frictional effects as the system approaches land, and the system will rapidly weaken from here forward. Dissipation over or just along the east coast Tanzania is forecast by 48 yours, if not a bit earlier.