APCEDI Alert 13P, Cyclone Ivy #8, 2004

Dear Colleagues

Alert 8, Cyclone Ivy 13P / 24 February 2004, Sydney 23:30 EDT

Cyclone Ivy continues to behave unusually. This evening it seemed to lose much of its deep central convection and weakened slightly to a minimal Category 1 storm or maybe even a little less. However, it has ceased any northern movement as it is now drifting slowly west at about 7 knots.

The deepest convection has been to the north of Ivy’s centre over Anuta and Tikopia for most of the evening. However it seems to be consolidating around Ivy’s centre which is about 50 km east of the Banks Group. On its current track this central area of deep convection will be moving over the Banks Group and Maewo, Pentecost and Ambae in the next 2-4 hours.

Feeder bands with intermittent squalls and heavy rains cover much of the Solomons and Vanuatu.

All day most predictive models have continued to show an imminent southern shift in the storm’s track, and this may be beginning soon. The official track out of the JTWC still has Ivy moving over Maewo, Ambae, Santo and Malakula and strengthening to Category 3 by the time it is west of Malakula. However, the latest Nadi forecast is noting that the decrease in structure and organisation in the last 6 hours combined with the effects of the mountains on Santo may inhibit much strengthening. In any case, the models have been very divergent and uncertain all day, so the APCEDI warnings will continue for all of Vanuatu north of Efate and all the Santa Cruz Group.

The current situation is summarised as follows:

Damaging Sustained Category 1 Cyclonic Gales and Heavy Rain
Solomons
Anuta
Tikopia

Sustained Gales and Heavy Rain approaching damaging Category 1 force in the next 2-4 hours
Solomons
Vanikolo
Utupea
Vanuatu
Banks Group (entire group)
Torres Group (entire group)
Maewo
Pentecost
Ambae

Intermittent Gales and Heavy Rain possibly approaching sustained Category 1 force over night
Solomons
Nendo
Nupani
Duffs
Swallows
Vanuatu
Torres Group (entire group)
Santo
Ambrym
Malakula

Alert for Increasing Threat of Gales and Heavy Wind tomorrow
Vanuatu
Epi
Shepherd Islands
Efate

Given the continuing Category 1 nature of the storm, damage at this time should be light to moderate and localised. It will likely include lowland tidal flooding and flash-flooding in hill areas. Some crop damage is also likely. As Ivy continues to be slow moving, this will likely result in heavy localised rainfall which could result in flash-flooding of mountain and hill areas as well as known flood prone areas. This is especially critical for the large Vanuatu Islands particularly Santo. Due to the islands’ very high relief and the slow movement of the storm, flash flooding will be a major threat throughout tonight and tomorrow especially if the the storms passes over the islands slowly or even stalls. If a central eye wall manages to emerge later tonight, and the storm strengthens to Category 2-3, damage along its path will certainly be more severe.

Anuta and Tikopia
By this time Anuta and Tikopia will have been subjected to very heavy rains, high seas and and sustained Category 1 gales for about 16 hours with another possible 5-10 hours of the same. This is likely resulting in tidal flooding of low-lying areas, crop damage and possibly some damage to unstable structures. However, the overall damage will not be anywhere as bad as with Cyclone Zoe. However, the cumulative effects of 3 major cyclones in 14 months (Zoe, Gina and now Ivy) may well be wearing down the ability of the people and their environment and its resources to sustainably cope. NDMO and Donors should endeavour to make contact with the islands as soon as the storm passes to assess both the immediate effects of Ivy and cumulative effects of the last 3 storms on the overall situation.

General Alert
Authorities in Vanuatu from the Torres Islands to Efate (including Torres and Banks Islands, Pentecost, Ambae, Santo, Malakula, Ambrym, Paama, Ulveah, Epi, Shepherd Islands and Efate including all small islands in these areas) as well as all of the Santa Cruz Group in the Eastern Solomons should be on alert, monitor the path of the storm closely throughout tonight and tomorrow and take immediate actions to protect people and property. People in mountain areas along the eastern and southern slopes of ranges should be on alert for heavy rain resulting in flash flooding. Low lying coastal areas especially along east and southern parts of large islands should also be on alert for tidal flooding.

Concerns in New Caledonia, the main islands of the Solomon Islands and the islands of Southern Vanuatu should continue to monitor this storm as it develops over the next few days. Outermost feeder bands are bringing rains and gusty winds to many of these areas as far away as Guadalcanal and the Louisades, and this will likewise increase during the day tomorrow.

APCEDI will continue monitoring the event. More detailed information about the storm can be found on

https://metoc.npmoc.navy.mil//jtwc.html
http://www.met.gov.fj/advisories.html
http://www.nrlmry.navy.mil/tc_pages/tc_home.html

Kevin Vang
APCEDI Coordinator