Significant new cyclone threat emerging
Long range computer models, which accurately predicted Cyclone Yasi's exact path and strength up to to 10 days in advance, are now picking a new cyclone is going to form directly north of New Zealand in the next 7 days reports WeatherWatch.co.nz.
Head weather analyst Philip Duncan says the potential cyclone could pose a threat to several nations including New Zealand. "The long range computer models are clearly showing a tropical depression forming somewhere around New Caledonia this coming weekend and by early next week it may well be a severe tropical cyclone".
Mr Duncan says Vanuatu, New Caledonia, Fiji and New Zealand will all be at some level of risk from the system if it follows the current modelling. "While we've found the long range models to be bang on all summer it doesn't mean this will 100% happen. We need to monitor the daily updates and we'll do our best at informing New Zealanders of the potential risk".
Image: ECMWF weather map showing a sizeable tropical cyclone north of NZ and a small low east of Gisborne on Wednesday next week. It's still too early to know the exact path beyond this map.
WeatherWatch.co.nz says the chance of this next tropical storm reaching New Zealand is "moderate" based on current modelling.
"As with all tropical lows it doesn't take much of a shift to spare New Zealand - we'll certainly be hoping for that - but considering we've had four named storms reach our country in just the past few weeks it wouldn't be out of the question for this to do the same".
The global models, produced by ECMWF in Europe, show a large scale cyclone, potentially category 4 strength, tracking south east north of New Zealand. The maps currently only go as far as Wednesday of next week so beyond that comes down to guess work at this early stage.
"This is simply a heads up that a tropical storm may be forming next week. It's too early to say where it will track for sure but the current predicted position does pose a risk to northern New Zealand" says Duncan.
GFS, which also produce long range maps, are predicting a new low will form in the Coral Sea by this weekend however GFS don't forecast as long range as ECMWF.
All maps are showing a large belt of unstable air which stretches from western Australia, along the northern coastline and then towards Fiji. It's this area that has seen all the cyclones form this summer and numerous tropical lows.
Following severe Cyclone Yasi the tropical activity dropped dramatically north of New Zealand however conditions have been gradually building over the past week.
WeatherWatch.co.nz says we are only at the half way mark of this cyclone season and NIWA predicts another five or six tropical cyclones are yet to form.
With such a strong La Nina in force it's likely the cyclone season will run later this year predicts WeatherWatch.co.nz.