SIO: JENNA - Tropical Cyclone (11U)

[Subtrop]

91S INVEST 260102 1200 10.0S 88.3E SHEM 15 0

[cycloneye]

Developing Tropical Low 11U to impact Cocos (Keeling) Islands as it passes close by on Monday.

Area affected
Warning zone
Cocos (Keeling) Islands.

Watch zone
None.

Cancelled zone
None.

At 9:30 am Cocos Islands Time
At 9:30 am CCT

Intensity
tropical low, sustained winds near the centre of 75 kilometres per hour with wind gusts to 100 kilometres per hour

Location
within 45 kilometres of 7.8 degrees South, 93.7 degrees East and 600 kilometres northwest of Cocos (Keeling) Islands

Movement
east at 29 kilometres per hour

Tropical Low 11U is developing well to the northwest of the Cocos (Keeling) Islands. It is expected to move east to southeast on Sunday and then southwards on Sunday night.

The system is expected to move close to the Cocos (Keeling) Islands during Monday with gales likely on the eastern side of the tropical low. Cocos (Keeling) Islands are more likely to experience gales if the system takes track over or to the west of the Islands. By Tuesday the system will be moving southwest away from the Cocos (Keeling) Islands.

Hazards

GALES with DAMAGING WIND GUSTS to 110 km/h may develop over Cocos (Keeling) Islands from Monday morning, if the system takes a track closer to or west of the Islands.

Rainfall will increase during Monday and may be heavy if the system takes a track closer to or west of the Islands.

[cycloneye]

[cycloneye]

Tropical Low 11U to pass close to the Cocos (Keeling) Islands today.

Warning zone
Cocos (Keeling) Islands.

Watch zone
None.

Cancelled zone
None.

Details of Tropical Low 11U at 6:30 am CCT:

Intensity
Tropical Low, sustained winds near the centre of 65 kilometres per hour with wind gusts to 95 kilometres per hour.

Location
within 35 kilometres of 11.0 degrees South 97.4 degrees East, estimated to be 145 kilometres north northeast of Cocos (Keeling) Islands.

Movement
south southeast at 25 kilometres per hour.

Tropical Low 11U is developing to the north northeast of the Cocos (Keeling) Islands. It is expected move in a southerly direction today, and should pass just to the east of the islands. Gales are likely on the eastern side of 11U during today, possibly extending to the western side this evening as 11U develops.

By Tuesday morning, 11U will be to the south of the Cocos (Keeling) Islands, turning southwest and moving further away.

Hazards

GALES with DAMAGING WIND GUSTS to 100 km/h may develop over Cocos (Keeling) Islands during this morning if the system tracks over or to the west of the Islands. During this afternoon and evening, gales could also occur over the islands if 11U develops into a tropical cyclone. Winds should then start to ease overnight.

Heavy rainfall is expected today as 11U passes by, before easing overnight.

[cycloneye]

Tropical Cyclone Jenna (11U) has formed close to the Cocos (Keeling) Islands. Dvorak analysis yields DT=3.0 using a curved band pattern (0.7 wrap). MET is 3.0 based on a D+ 24-hour trend, PT is 3.0 with FT/CI=3.0. Objective guidance at 0530 UTC (1-minute mean) has started with ADT 45 knots, AiDT 35 knots, DPRINT 41 knots, DMINT (2356UTC) 30 knots and SATCON unavailable. Surface observations from the nearby Cocos Islands have shown an increase in wind speeds to near gales at times with a sudden drop off in wind speeds consistent with the centre just to the east, the lowest pressure recorded was about 992 hPa. Intensity based on Dvorak and objective guidance, remains at 35 knots. Over the last 12 hours deep convective bands have developed and wrapped around the low-level centre. The environment is broadly favourable with warm SSTs, abundant moisture, good upper outflow to the south and deep vertical wind shear of around 15 knots from the NE. The passage of an upper trough to the south of the system during Tuesday will further enhance upper support and Jenna is forecast to reach a peak intensity of 60 knots late Tuesday or early Wednesday, there is a small chance it could reach hurricane force. By Wednesday another approaching upper trough in the central Indian Ocean is forecast to increase shear and this combined with the ingestion of dry air into the core of Jenna should weaken the system quickly. Jenna is currently being steered southwards as it transitions from being steered by the monsoon to the mid-level ridge to the east becoming the main steering influence. The system is moving southwards and currently passing to the east of the Cocos Islands, Jenna should begin to move away overnight Monday and during Tuesday. Guidance shows good agreement in a southwards motion with a turn to the southwest during late Monday or early Tuesday. Jenna should then move westwards and be out of the Australian Region by late Wednesday or early Thursday.

[sasha_B]

Cyclone Jenna was upgraded to 65 kt / 987 hPa on the JTWC's 21z advisory, making it the first TC to reach hurricane-equivalent strength in 2026.

[cycloneye]

At 8:00 am AWST

Intensity
category 2, sustained winds near the centre of 100 kilometres per hour with wind gusts to 130 kilometres per hour

Location
within 35 kilometres of 15.2 degrees South, 95.5 degrees East and 365 kilometres south southwest of Cocos (Keeling) Islands

Movement
southwest at 21 kilometres per hour

Tropical Cyclone Jenna (11U) is located well south of the Cocos (Keeling) Islands. Jenna will continue to track to the southwest, away from the Cocos (Keeling) Islands over open waters in the Indian Ocean during the next few days. Jenna is expected to strengthen today before starting to weaken from Wednesday. It is not expected to impact Indian Ocean territories or the Western Australia mainland.

Details

[cycloneye]

Looks like it's forming an eye.

[sasha_B]

The eye is starting to clear out on VIS/true-color imagery, and ADT is up to CI 5.2. I suspect Cyclone Jenna is around 85 kt or stronger. KCZ for a 90 kt cyclone (based on an OW eye surrounded by LG w/ no eye adjustment + the assumption that Jenna has intensified since the last satellite bulletin & ADT is running a little high) would yield an MSLP around 969 hPa.

[cycloneye]

[sasha_B]

Jenna seems to have weakened now, although the JTWC operational track shows it still at its peak intensity of 90 kt and 968 hPa. IMO the peak occurred around 0500z and a little stronger, perhaps 95 kt and 963 hPa; it may have reached a similar intensity around 0800z, but satellite presentation has been deteriorating steadily since then, with the CDO warming and the eye losing clear definition.

Incidentally, the Australian BoM also has the storm as a Category 3 (on their scale), with 10-minute sustained winds of 80 kt (≈90 kt 1-min. sustained) and central pressure down to 967 hPa, as of 1200z.

[Ulf]

I was hoping this would attain a brief major status like with Bakung before weakening. Too bad.