APCEDI Alert SP/SI Cyclone Yani #4-2007: Cyclone Yani slowly moves southward through open waters west of Vanuatu.

The RSMC-Nadi Tropical Cyclone Centre and the Joint Typhoon Warning Centre continue to issue guidance on Cyclone Yani that is moving slowly southward in the open waters of the Coral Sea west of Vanuatu.

Cyclone Yani is currently centred 400 km northwest of Espirito Santo Island, Vanuatu or 360 km southeast of Rennell/Bellona, Solomons. Yani is currently at Category 1 strength on the Saffir Simpson Scale. It is moving very slowly southward at 4 kts with a forecast shift in direction to the southwest, but continued slow southerly meandering is likely in the next 12-24 hours. Satellites photos and data are indicating that Yani may be peaking in intensity with a slow weakening trend possibly beginning later today or tomorrow.

On its current slow southeasterly track, no land areas are immediately threatened, and Yani is continuing to move through the open sea. Nonetheless, early season storms are notoriously unpredictable, and current model guidance for Yani while improving is still somewhat divergent in these weak steering conditions. Therefore, all interests in Makira, Rennell and Bellona, Northern and Central Vanuatu and Nouvelle Caledonie (New Caledonia)should pay close attention to this storm and be ready to make any preparations should conditions warrant and authorities advise. Seas in the area are now very rough and local small boating interests should stay in port until advised.

From the RSMC-Nadi Tropical Cyclone Centre

Tropical Disturbance Advisory Number A9 issued from RSMC NADI
Nov 23/1957 UTC 2006 UTC.

Tropical Cyclone YANI [CAT 3] 04F [960hPa] centre was located near 13.8S 163.0E at 231800 UTC. Position good based on HRES MTSAT EIR imagery with animation. Cyclone moving south about 04 knots but expected to gradually turn south-southwest. Maximum 10-minute average winds estimated at 75 knots increasing to 85 knots in the next 24 hours. Winds over 63 knots within 30 miles of centre, and winds above 47 knots within 50 miles of centre, and winds above 33 knots within 120 miles of centre in the southeastern semicircle and within 90 miles of centre in the northwestern semicircle.

Organisation steady past 6 hours. Ragged cloud-filled eye still clearly evident on EIR imagery. Outflow good to south and fair elsewhere. Dvorak based on Embedded centre pattern with W surround yielding DT5.0. MET and and PAT at 4.5. Final T based on DT thus T5.0/5.0/D1.5/24hrs. Cyclone lies underneath a 250-hPa ridge axis in a divergent region. Shear gradually increasing over system. SST around 28-29C. A mid-level anticyclone to the east with an associated ridge extending southwest is expected to steer Yani towards the south-southwest. This will bring the cyclone into a region of stronger shear and cooler SSTs. Global models generally agree on a
south-southwest track with gradual intensification only in the short term.

FORECAST:
12hrs valid 240600UTC near 14.5S 162.7E mov SSW at 04kt with 75kt close to centre.
24hrs valid 241800UTC near 15.2S 162.4E mov SSW at 04kt with 85kt close to centre.

OUTLOOK:
36hrs valid 250600UTC near 16.1S 162.0E mov SSW at 04kt with 75kt close to centre.
48hrs valid 251800UTC near 17.3S 161.5E mov SSW at 05kt with 60kt close to centre.

The next Tropical Disturbance Advisory on TC YANI will be issued around 240200 UTC.
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APCEDI will continue to issue further bulletins on Cyclone Yani as the need arises.

Kevin Vang
APCEDI Coordinator

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