APCEDI Alert 13P, Cyclone Ivy #11, 2004

Dear Colleagues

Alert 11, Cyclone Ivy 13P / 25 February 2004, Sydney 1800 EDT

The centre of Cyclone Ivy is slowly moving over Maewo, Pentecost and Ambae with the eye over Ambae. It is slowly moving south. A very defined but slightly cloud filled eye formed about 4-5 hours ago just west of Mere Lava. However interaction with the larger islands and entrainment of some dryer air has again made the eye rather indistinct. It is maintaining its strength as a Category 2 Cyclone. However, interaction with the larger islands may drop its strength back to a borderline Category 1-2 Cyclone, or if the centre gets into open water, strengthening is also possible. So the exact track is very critical.

The slow moving nature of the storm continues to be problematic with high rainfall totals throughout the Northern Islands of Vanuatu, and the likelihood of further high totals in the next 12-24 hours. Torrential rains are now over Santo, Malakula, Maewo, Pentecost, Ambrym, Ambae Epi and the Shepherd Islands. Torrential rains are just starting to move into Efate. Due to the slow forward speed of Ivy, this will continue into tonight and tomorrow while spreading southward.

Inner feeder bands with severe gales and heavy rains continue to effect Anuta and Tikopia. However, a pocket of more dry weather has moved over the Banks and Torres Islands giving them their first respite in 2 days. Further to the north, the weather is starting to clear over the Santa Cruz Group with only isolated heavy showers.

Most predictive models are now showing Ivy tracking southerly across the length of Vanuatu throughout the next 24-48 hours. The official track out of the JTWC has Ivy moving over the Northern Islands this evening to just west of Vila tomorrow morning as a Category 2-3 storm and then on to the Loyalty Islands and New Caledonia tomorrow as a Category 3. As such, the APCEDI warnings will continue all of Vanuatu from the Banks Group south and for Anuta and Tikopia in the Solomons. The APCEDI warnings for the Santa Cruz Group and the Torres will now be lifted while still noting that isolated, intermittent heavy showers are still likely. If the eye feature maintains it current course, it will pass to the west of Pentecost and would be over Ambrym in about 4-6 hours.

The current situation is summarised as follows:

Possible Damaging Category 2 Eyewall-strength Gales and Torrential Rains
Vanuatu
Maewo (Entire Island)
Pentecost (Entire Island)
Ambae (Entire Island)
Santo (East and South Coast)
Malakula (East and South Coast)
Ambrym (Entire Island)

Damaging Sustained Category 1-2 Gales and Heavy Rain
Vanuatu
Mere Lava (but soon decreasing)
Santo (West Coast)
Malakula (West Coast)
Epi
Shepherd Islands

Sustained Gales and Heavy Rain approaching damaging hurricane force in the next 2-4 hours
Vanuatu
Efate

Sustained Gales and Heavy Rain approaching damaging hurricane force in the next 4-8 hours
Vanuatu
Erromango
Tanna
Anatom

Intermittent Gales and Heavy Rain associated with Inner Feeder Bands (Storm now moving away)
Vanuatu
Banks Group
Solomons
Tikopia
Anuta

Given the continuing Category 1-2 nature of the storm, damage at this time should be light to moderate and localised. However, locally moderate to severe damage could occur near to the centre of the storm. Main threats will continue to include lowland tidal flooding and flash-flooding in hill and mountain areas. Varying degrees of 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.

Larger Vanuatu Islands
The centre of Ivy is now over Ambae, Maewo and Pentecost. In addition to these islands torrential rains and damaging Category 1-2 gales have also been pounding Santo, Ambrym and Malakula for most of the day. This rough weather moved into Epi and the Shepherds this afternoon and the situation will begin deteriorating in Efate and Vila this evening and tonight. The slow moving nature of the storm mean that rainfalls in the hundreds of millimetres will have been registered throughout the region and will be continuing. This will certainly be causing flash flooding of many stream valleys and larger rivers. The situation in hill and mountain areas of Santo, Malakula, Ambae and Pentecost is of particular concern. GOV, NDMO and Donors should now prepare themselves for needing to make widespread assessments across most of the big islands of northern Vanuatu tomorrow and in the following days. This may be difficult as Vila itself will be under the gun much of tomorrow. In addition to flash flooding, coastal flooding and wind damage can be expected at least in localised areas near the centre.

Banks Group
The centre of the storm is finally moving away from Mere Lava and the rest of the Banks Group. The whole group has had very heavy rains, very rough seas and increasingly severe winds for almost 36 hours. With the centre having slowly moved over Mere Lava, this outer island may be particularly hard hit. With the cyclone pulling away from this Group, assessments should be done of the areas to determine the degree of wind damage and flooding. Crops are likely badly affected in some areas.

Anuta and Tikopia, Solomons
Anuta and Tikopia are now out of the centre of the storm but unfortunately still continue in the inner feeder bands. Gales and heavy rains should start subsiding in the next 6 hours and become more intermittent and less severe after this. Light to moderate damage caused by tidal flooding of low-lying areas, crop damage and possibly some damage to unstable structures is expected given the nearly 36 hours of punishment by this storm. 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 to assess both the immediate effects of Ivy and cumulative effects of the last 3 storms on the overall situation.

Torres Groups, Vanuatu and Santa Cruz Group, Solomons
Inner feeder bands with heavy rains and squalls are now beginning to break up and subside over the region. Seas will remain very rough. The Torres Group, Vanikolo and to a lesser extent Utupua have received very heavy rainfall from their proximity to this slow moving storm so some flooding may have occurred. They should be assessed later today. The remainder of the Group has likely only experienced minor coastal flooding, but contact to all the all the smaller outliers should be undertaken to verify this.


General Alert
Authorities in Vanuatu from the Banks Group to Anatom (including Torres and Banks Islands, Pentecost, Ambae, Santo, Malakula, Ambrym, Paama, Ulveah, Epi, Shepherd Islands, Efate, Erromango, Tanna and Anatom including all small islands in these areas) as well as Anuta and Tikopia in the Eastern Solomons should conntinue 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 including the Loyalty Islands should continue to monitor this storm as it develops over the next few days.

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