Powerful Storms in a Warming World — Cook is Strongest Cyclone to Strike New Zealand in Nearly 50 Years

About 12 hours ago, at 18:30 local time (06:30 GMT) on Thursday, Cyclone Cook roared out of an ocean that has now been considerably warmed by human-forced climate change to made landfall in the Bay of Plenty region of New Zealand. Packing wind gusts of up 90 miles per hour and lashing the region with 1/2 to 1 inch per hour rainfall rates, the storm is the most powerful cyclone to strike New Zealand since 1968.

Most Powerful New Zealand Cyclone in Nearly 50 Years

(New Zealand under a swirl of clouds as Cook makes landfall. Image source: LANCE MODIS.)

The storm raked a region that had already seen saturating, long-lasting, rainfall from the remnants of Cyclone Debbie just one week before. As a result, trees unable to gain purchase in the weakened soils uprooted en-masse. Power was knocked out in Whakatane and in numerous other locations along Cook’s path — cutting off at least 11,000 residences. Locals described gusts like freight trains as hundreds huddled in evacuation shelters. Flights out of Rotorua, Tauranga, Napier and Hamilton in the North Island, and Nelson and Blenheim in the South Island were all canceled.

The 30 foot swells and a resulting storm surge in the Bay of Plenty region were expected to result in serious coastal flooding and damage to shore-front structures. But the chief worry from the system, after Debbie’s devastating rains, was more precipitation-related flooding.

(GFS 7 day rainfall forecast for New Zealand shows considerably above average precipitation from Cook. See also GFS rainfall model runs.)

GFS model runs indicated the potential for 4-8 inches of rainfall or more near New Zealand population centers along the path of Cyclone Cook. And for many regions, these totals equal about 1-2 months worth of rainfall at this time of year. Last week, 7.5 inches of rainfall over just two days resulted in a levee breach at Edgecumbe on North Island — flooding the entire town and forcing nearly all the residents to evacuate. And there is some concern that Cook’s follow-on to Debbie will produce similar trouble.

Warming Ocean Waters and High Amplitude Waves in the Jet Stream Feed Storm Pattern

Cook is interacting with a trough to the west of New Zealand in a manner that is broadening the storm — spreading its wind field and rainfall over a larger region than a purely tropical system would typically impact. The trough had dipped down from the Southern Ocean through an extended Jet Stream wave before it became cut-off and linked up with Cook.

(Cook is presently centered between New Zealand’s North and South Islands [roughly under the green circle]. The swirl of clouds and wind to the west of Cook is a second low pressure system that was cut off from a trough sweeping south and west of New Zealand on Tuesday and Wednesday. Cook is interacting with this trough in a manner than is broadening its wind field and enhancing rainfall potentials. Image source: Earth Nullschool.)

The far northward extent of this trough is indicative of higher amplitude Jet Stream waves that have been associated with warming temperatures at the polar regions due to climate change. And the zone south of New Zealand over Antarctica has featured a strong dipole — with well above normal temperatures facing off against a wall of cold air. This dipole has facilitated troughs and facing ridges that extended well into the middle latitudes.

(Cyclone Cook fed on far warmer than normal waters which enabled it maintain intensity as it moved into higher latitudes. Interaction with a trough remnant left over from a high amplitude wave in the Jet Stream also contributed to this extreme weather event. Image source: Earth Nullschool.)

Meanwhile, Cyclone Cook itself fed on 1-2 C warmer than normal sea surface temperatures surrounding New Zealand. These warmer than normal waters allowed Cook to retain strength and to interact with the polar originating trough in a manner that arguably intensified and broadened the scope of this severe weather event.


Cyclone Cook: Evacuations as Storm Lashes New Zealand

Concerns Increase as Cook’s Path Shifts Toward Population Centers

Cyclone Cook vs Cyclone Debbie


GFS rainfall model runs

Earth Nullschool

Hat tip to LeslieGraham (please stay safe!)

Hat tip to wili

Leave a comment


  1. unnaturalfx

     /  April 13, 2017

    This is O T but from a few threads back : :
    First seismic sensor installed to give early warning on new ‘exploding pingos’ . Lets hope these stay silent !

    • unnaturalfx

       /  April 13, 2017

      Looked at these pictures many times and they always just stun me .

    • Yep. Now we’re tracking permafrost methane explosions like we used to track earthquakes. Anyone who doubts the present urgency of the climate situation needs have their sanity checked.

      • Erik Frederiksen

         /  April 13, 2017

        Indeed, there’s only more than twice the carbon currently in the atmosphere locked up in the permafrost alone.

        • God help us. Earth is like the proverbial Sodom and Gomorrah. All immersed in our wicked carbon intensive lifestyles. In full denial mode.

  2. wili

     /  April 13, 2017

    Thanks for another great article and for the hat tip.

    Do keep us updated if possible LG, and anyone else in the area. But first, of course, keep you and yours safe.

    • Hilary

       /  April 14, 2017

      Updating from Napier city on NZ’s East coast:
      After a wild wild noisy evening the storm moved south. We fared OK, some debris & damage to our garden crops & fruit trees, maybe the olive (laden) wont survive, but nothing serious. Plenty of tree damage in my immediate neighbourhood but no flooding. Power still out in some districts nearby but not where I live. Now the sun is out, it’s 24’C & no wind!
      You can see more details & updates nationwide on here:

    • Hilary

       /  April 14, 2017

      Have a look at this bedraggled albatross chick on the cam near Dunedin, it has been digging in the dirt so dirty, but they are protecting it from the weather with this screen too!

  3. Erik Frederiksen

     /  April 13, 2017

    Tropical cyclones derive their strength from warm water and much of the resulting damage is due to storm surge. Add heat to the system and a higher base sea level and you get more destructive storms. Kerry Emanuel has done interesting work in this area.

    I don’t think one can say that global warming caused Sandy, but ocean temperatures were several degrees above normal for both Sandy and typhoon Haiyan and sea levels were higher than before the Industrial Revolution, so global warming exacerbated the storms. The extra foot or so of sea level rise caused Sandy to flood an additional 25 square miles.

    Another interesting thing about Sandy. Changes in the jet stream, perhaps due to Arctic ice decline, allowed Sandy to follow an unusual, and unusually damaging course; directly into land with the dangerous semi-circle of the storm piling water ashore.

    Katrina and Sandy didn’t spur us to action and Katrina killed 1,836 people. If we wait to act until a category 6 hurricane plows through NYC or Miami on top of 1-2m of sea level rise it will be a little late.

    • It’s a contributing factor. One that adds to peak storm intensity, storm formation, storm range, and storm duration.

      • Erik Frederiksen

         /  April 13, 2017

        I read of a couple of storms which blew up surprisingly fast, going from Tropical Storms to strong category 5 storms in just 24 hours. The tremendous ocean heat gives the storms so much energy to draw upon.

        • It spikes convection and CAPE, for example. Key contributors to both bombification and increases in maximum potential intensity. The pole to tropical interaction is another weird influence that science hasn’t come fully to grips with as yet.

    • Ridley Jack

       /  April 13, 2017

      A cat 6 in new york I know theres not a rating cat 5 is the highest but what if a storm like hayian hit new york is that possible

  4. Erik Frederiksen

     /  April 13, 2017

    I heard the sound of a thunder, it roared out a warnin’
    Heard the roar of a wave that could drown the whole world
    . . . .
    And it’s a hard, and it’s a hard, it’s a hard, it’s a hard
    And it’s a hard rain’s a-gonna fall

  5. Jeremy in Wales

     /  April 13, 2017

    robertscribbler / April 12, 2017

    The 70s ice age yarn was the first climate misinformation campaign. It’s worth noting that even then a majority of the science was settled on warming. It might have been a 70-30 or 80-20 consensus then. But it was considerable, though not the 97 to 99 consensus that we have now.

    lesliegraham1 / April 13, 2017

    “A review of climate change literature between 1965 and 1979, undertaken in 2008, found that 44 papers “predicted, implied, or provided supporting evidence” for global warming, while only seven did so for global cooling.
    “Global cooling was never more than a minor aspect of the scientific climate change literature of the era, let alone the scientific consensus…” the reviewers remarked.”

    It is a fact that not one of them predicted a “new ice age.”
    It is a fact that all of the papers about cooling concerned unrestricted aerosol pollution, and it is a fact that we stopped doing that.
    But then you all knew that anyway I’m sure.

    I first became interested in Climate and climate change in the 1970’s and I do not think these posts really address the arguements or subjects that took attention at that time. We need to remember that this was the decade that made massive strides in our understanding of processes involved with climate change and a detailed understanding of past climates. Remember that it was only in the 1960s that continental drift decame an accepted theory.

    We had deep ocean cores and ice coring that confirmed the ice age cycles and Milankovich affect eg Hayes Imbrie & Shackleton. We had studies by Prof. Lamb of past historical climates (Dust Veil Index) and work to construct the Central England temperature record, sun spot cycles etc.

    There was a sudden realisation that sudden slight climate changes could have dire consequences on human affairs especially with regard to drought & food production (Sahel and Soviet Union).

    One of the first books I bought regarding climate was a popular science book “The Climatic Threat” by John Gribben (a astrophysics PHD and ex Nature staff member, so no fool) and this book reflects the large uncertainties they were coping with at that time. It did not promote a new Ice Age and pointedly ruled this out for at least 12,000 years (although Nigel Calder had promoted the idea in the UK via a TV series), but a cooling to the end of the 20th century was considered a reasonable possibility caused by aerosols and sun cycles. CO2 and other gases were recognised as warming agents but over a longer timescale 75-100 years for 1°C – 3°C (over the following 6 years that rapidly changed). There was even a view in a 1976 paper in Nature by Dr Bacastow that the increase in CO2 was a natural variation caused by the Southern Oscillation.

    So while the science was obviously not settled on a new ice age, it was neither entirely settled upon global warming, although the evidence was rapidly being found and the basic physics was long established with regard to CO2. John Gribben had a tendency, which you could sense he was trying to restrict, to favour a sun link to climate, due to his background, but did not deny a CO2 link. But in the 1970s it is fair to say that any CO2 affect was thought to be far into the future, there was no sense of urgency, ozone was probably seen as a more important as fluorocarbons had been identified as a hazard as had Concorde.


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