Tropical Cyclone Cook

  • Visible satellite image of Cyclone Cook making landfall over New Caledonia. Image credit: NASA.

    Forecast track for Cyclone Cook issued at 00 UTC on 10/04/2017. Image Credit: Joint Typhoon Warning Center.

    Visible satellite image of Ex-Cyclone Cook, as it approaches the North Island of New Zealand. Image Credit: NASA.

  • Tropical Cyclone Cook
    15.04.2017 17:00

    Cyclone Cook formed in the south-western Pacific Ocean on the 8th April, close to the island of Vanuatu. In a favourable environment of warm sea surface temperatures and low environmental wind shear, the cyclone intensified into a Category 3 storm as it made landfall in New Caledonia on April 10th

    Both islands were severely impacted by the storm, which brought strong winds of up to 180 kph (112 mph) and flooding rains of up to 400 mm (16 inches) to parts of New Caledonia. The heavy rains increased the risk of landslides in the island’s mountainous interior. New Caledonia had not experienced a direct hit from a tropical cyclone since Cyclone Erica in 2003.

    However, the mountainous terrain disrupted the flow within the storm, and it subsequently weakened over the following days as it tracked south-east over colder waters towards New Zealand. The storm eventually lost its tropical cyclone status on the 12th April, but remained a dangerous extratropical cyclone with strong winds and heavy rainfall, as a result of all the tropical moisture tied up within it.

    There were concerns for up to a week beforehand that the storm could track across New Zealand, and the main computer models eventually fine-tuned their forecasts, all predicting the storm to move south-westwards across both the North and South Islands. This is an unusual track for a storm to take in the Southern Hemisphere, with low pressure systems typically moving from west to east. With the direction Cyclone Cook was travelling, it meant that the whole country was in the firing line for strong winds and torrential rain.

    The real concern was the potential impact of the heavy rain, in flood hit regions of the North Island which had been battered by the remnants of Cyclone Debbie just a week before. Ex-Cyclone Cook eventually made landfall in the Bay of Plenty during the evening of the 13th April. This sparked scenes of chaos in Auckland, as thousands of people tried to get home early for the Easter Weekend, before the storm’s arrival.

    Fortunately, much of the country was spared the worst of the storm, as it took a track just to the east of the forecast.  This shifted the zone of strongest winds and heaviest rain just offshore, and meant that major cities such as Auckland and Wellington dodged a bullet. The storm still brought winds of up to 200 kph (124 mph) to exposed coastal locations of the North Island. Rainfall totals were also lower than forecast, as the storm moved quickly to the south to merge with a second area of low pressure over the Tasman Sea, and so the heavy rain didn’t last so long. 

    By: Richard Martin-Barton