Meteorological Society of New Zealand (Inc.)

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 1 ISSN 0111-1736 (Print) ISSN 2624-4640 (Online)

Meteorological Society Of New Zealand (Inc.)

NEWSLETTER 158 Spring 2019 See our website for the pdf

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 2 Meteorological Society Of New Zealand (Inc.) NEWSLETTER 158 Spring 2019 PO Box 6523, Marion Square, Wellington 6141, New Zealand Please forward contributions to Bob McDavitt, [email protected]

CONTENTS Page Foreword from our President 3-4 AGM 5-6 Around the Regions 7 Autumn: NIWA review 8-10 Notable events 10-15 Pick of the clips 16-468

Your Committee until the AGM President: Michael Martens Immediate Past President: Sylvia Nichol Secretary: Katrina Richards Treasurer: Gregor Macara Circulation Manager: Lisa Murray Website Liaison: Stefanie Kremser Journal Editor: Nava Fedaeff Newsletter Editor: Bob McDavitt Auckland VP: Petra Pearce Wellington VP: [vacant] Christchurch VP: Jiawei Zhang Dunedin VP: Daniel Kingston Hamilton VP: Tim Gunn General Committee: Luke Sutherland-Stacey, Mike Revell HydroSoc Liaison: Charles Pearson Views and endorsements expressed in this newsletter are those of the contributors and advertisers, and not necessarily those of the Meteorological Society of New Zealand. The mention of specific companies or products does not imply that they are endorsed or recommended by the Society.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 3 From our President I would like to use this opportunity to update you on the progress of prepara- tions for the annual conference of the society and what I have been up to during the last few months.

Our annual conference will take place in Wellington from 25.11.-27.11. this year and will cover all aspects of climatology and meteorology, from observations, numerical predictions to research and climate projections. We are expecting around 100 participants, including invited speakers and keynote presenters. To further elevate the importance of our conference and to increase its visibility beyond the atmospheric science community, the organising committee and I are working on inviting key people from central and local government as guests and/or invited speakers. At a forum with government ministers and the prime minister on the 19th of August I was able to talk with Climate Change Minister James Shaw and subsequently have been able to secure his attendance for this year’s conference. Moreover, Climate Change Ambassador Kay Harrison was vis- iting MetService on the 22nd of August and I had a chance to talk with her not only about the important work MetService is doing for New Zealand and the Southwest Pacific region, but also advocate for the MetSociety and the important work we are doing by encouraging the interest in atmosphere, weather and climate, particularly as related to the New Zealand region (see pictures below). I invited her to our annual conference in November and she has also subsequently accepted the invitation. Furthermore, we are in contact with key people from other ministries and local government and hope to secure a few more guests and invited speakers for this year’s conference. As a reminder, if you haven’t done so already, please submit your abstract and regardless if you are presenting or not, make sure you register for the conference before 01.10.19 to be eligible for early bird tickets and do consider buying tickets for the dinner, for which places are limited. For more information and to register, please go to our conference website: https://www.metsoc.org.nz/metsoc-conference/

In other news, I was at the Royal Society’s constituent forum 1st of July. There we discussed the future of the Royal Society, how the Society can better and more efficiently engage with its constituent members and how to increase the cultur- al diversity of the Royal Society and its awards and fellowship programs. Fur- thermore, I’ve been working closely on the MoU with Andrew Marshall (current president of the Australian Meteorological and Oceanographic Society) and we will likely have the agreement signed by the end of September. This will result in mutual benefits for members of both societies. Finally, we have made great progress in overhauling our prizes and awards for outstanding scientists and early career scientists and will hopefully be able to present the new rules and guidelines at the AGM in November.

Ngā manaakitanga, Michael Martens, President

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 4

From left to right (Michael Martens [President of the MetSociety NZ], Norm Henry [General Manager Science Strategy, MetService], Kay Harrison [Climate Change Ambassador, MFAT], James Lunny [WMO Manager, MetService]).

Michael Martens in conversation with Kay Harrison.

More information about the AGM and results from the photo competition will be emailed later this month.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 5

YOU ARE INVITED TO ATTEND OUR AGM (even if not at our conference)

NOTICE AND Agenda for the 40th (XL) Annual General Meeting of the Meteorological Society of New Zealand

5:15 pm to 6:15 pm, Monday 25 November 2019 Te Toki a Rata Lecture Theatre 1, Victoria University of Wellington (Kelburn)

1. Attendance 2. Apologies 3. Confirmation of minutes of previous AGM. 4. Matters Arising 5. President’s report (President, Michael Martens) 6. Treasurer’s report (Treasurer, Gregor Macara) 7. Appointment of Financial Reviewer 8. Subscription rate (Circulation Manager, Lisa Murray) 9. Election of Officers (Immediate Past President, Sylvia Nichol) 10. Other Matters • Proposed changes to the Constitution (see next page)

If you want your apology recoded please send to [email protected]

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 6

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 7 Meetings during Winter around the regions (not many) Christchurch University of Canterbury next Monday (June 17th). "Energetic constraints on climate model errors in precipitation" by Prof. Christian Jakob Prof Christian Jakob is a scientist at Monash University. He is a fellow of the Australian Mete- orological and Oceanographic Society and won the Atmospheric Sciences Ascent Award in 2016.

Climate models have significant errors in precipitation globally, but in particular in the tropics. Most models overestimate annual mean tropical precipitation, with the largest errors oc- curring over the warm tropical oceans of the Western Pacific, Indian Ocean and Atlantic. In addition to the mean errors, there are significant shortcomings in the rainfall variability in space and time. Given its immediate impact on tropical rainfall, most of the errors are usually attributed to shortcomings in the representation of deep tropical convection, and most attempts at their remedy focus on changes to the processes involved in it.

We show that in observations the tropics, defined as the latitude belt from 30 degrees north to 30 degrees south, are very close to radiative convective equilibrium every day. This indi- cates that to first order tropical precipitation and radiative cooling are in balance even on short (daily) timescales. We show that this balance is a result of small regions of precipitation with very inefficient cooling – the deep tropics – and large regions of efficient cooling but little precipitation – the subtropics. We show that models obey this balance. This opens the intriguing possibility that mean rainfall errors in the deep tropics are the result of errors in radiative cooling and that the model’s convection is simply a slave to the radiative cooling away from the rainy regions.

We investigate this hypothesis using several models run in a variety of configurations, rang- ing from Aquaplanet experiments with the German ICON model, to AMIP simulations with a range of models with and without cumulus parametrization. The models produce a wide range of tropical rainfall values and all of them are directly related to the tropical radiative cooling. We investigate the key regions of radiative cooling changes as the model rainfall changes and highlight potential mechanisms involved.

We conclude that it is just as likely that climate model rainfall errors in the tropics are the result of errors in radiative cooling due to the misrepresentation of tropical cirrus and/or subtropical boundary layer clouds as they are the result of errors in the cumulus parametrization.

Wellington Monday 22 July, 6.00–7.00 pm Speakers: Thomas Coughlan (chair), David Hall, Amelia Sharman, Dave Frame and Sylvia Nis- sen. BWB Talk: Climate Crisis and Revolution Climate crisis is upon us. By choice or necessity, New Zealand will transition to a low- emissions future. But can this revolution be careful? Can it be attentive to the disruptions it inevitably creates? Or will carefulness simply delay and dilute the changes that future people require of us? Join as authors of the latest addition to the BWB Texts series, A Careful Revolution, explore the politics and practicalities of the low-emissions transition, touching on issues of justice, tikanga, trade-offs, finance, futurism, adaptation, and more. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -=- =-=

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 8

WINTER 2019 according to NIWA 7th-warmest winter on record and near normal rainfall These monthly summaries are available online, and may be viewed at the following website: https://www.niwa.co.nz/climate/monthly Overview Winter 2019 began on a chilly note, with snow falling in the South Island and the Central Plateau on 1 June. The wintry start was however not indicative of the season as whole, with snow events infrequent throughout the season . June was the driest winter month with below or well below normal rainfall for the majority of New Zealand. Several locations in southern coastal Canterbury and northern coastal Otago observed one of their driest Junes on record.

While July wasn’t as dry as June, a distinct lack of southerlies and frequent rounds of high pressure during the month led to unseasonably warm temperatures and New Zealand’s second-warmest July on record.

August was unsettled, characterised by frequent low pressure systems and a strong southwesterly flow – a pattern driven by a strongly negative Southern Annular mode early in the month. Frequent fog events, thunderstorms and tornadoes occurred during winter (see Highlights and extreme events section for further details).

The winter climate pattern was influenced by a polar jet stream that remained south of New Zealand during June, was weaker than normal in July, but occasionally passed over the country during August while interacting with the sub-tropical jet stream. This contributed to an unsettled end to the winter season. In the tropical Pacific, a central Pacific (Modoki) El Niño persisted during June and July before fading to neutral in August. New Zealand coastal sea surface temperatures were above New Zealand These two factors tipped the odds toward a warmer than average winter season for many locations. Winter as a whole saw average to above average temperatures across the country. The nationwide average temperature for winter 2019 was 9.0°C (0.6°C warmer than the 1981-2010 winter average, using NIWA’s seven-station temperature series which begins in 1909). This makes the winter of 2019 the seventh-warmest winter on record. : • The highest temperature was 21.6°C, observed at Wakanui on 3 July. • The lowest temperature was -9.2°C, observed at Lake Tekapo on 3 June. • The highest 1-day rainfall was 126 mm, recorded at Milford Sound on 13 July. • The highest wind gust was 182 km/hr, observed at Cape Turnagain on 13 August.

Temperature: Above average or near average throughout the country Mean temperatures for New Zealand were near average during June and August, and above average during July – it was the second-warmest July on record. For winter as a whole, temperatures were average (-0.50°C to +0.50°C of the winter average) to above average (+0.51°C to +1.20°C of the winter average) and it was New Zealand’s seventh-warmest winter on record. Some of the warmest temperatures compared to the winter average occurred in Otago, Southland and the Mac- kenzie district. Many locations experienced record or near-record high mean, mean maximum and mean minimum temperatures. Lake Tekapo and Ranfurly each experienced their second-warmest winter on record, with records going back to 1927 and 1897 respectively.

Rainfall: Variability month to month – near normal as a whole Winter began on a particularly dry note with below normal (50-79% of normal) or well below normal (<50% of normal) for the majority of New Zealand during June. The dryness lingered into early July and Water-

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 9 care urged residents of Auckland to use water wisely as water storage was 25% less than normal for the time of year. Wetter and more active weather arrived during July and continued into August, with the latter recording 28 rain days, a tie for the most rain days in a calendar month on record. When looking at the rainfall pattern for winter as a whole, rainfall was largely near normal. Small pockets of below normal rainfall were observed about Gisborne, Hawke’s Bay and parts of Otago

Soil moisture At the end of winter 2019, soil moisture was near normal for most of New Zea- land. Soils were drier than normal for isolated parts of inland north Otago and wetter than normal about Kaikoura.

Highlights: Rain and slips On 4 July, an active front preceded by a moist northerly flow brought heavy rain and high ele- vation snow to central and upper North Island and caused localised surface flooding and traffic delays. Parts of SH2 in Whakatāne closed due to flooding. On 10 August, heavy rain fell in eastern parts of Otago and South Canterbury. Flooding forced the closure of SH1 between Oamaru and Timaru. On 17 August, a period of heavy rain caused surface flooding in Levin. On 5 June, 1000 households lost power in Bay of Plenty as strong winds and heavy rain moved through the region. Flights were delayed out of Auckland airport due to poor weather conditions. On 12 July, a tornado near New Plymouth caused damage to trees, two buildings, and a trampoline. On 3-4 August, a combination of a deep low pressure system and strong winds generated large swells along the western coasts of New Zealand. Coastal erosion of up to 10 m was reported in Cobden (Greymouth), where a make-shift sea wall had been erected. Residents of six properties in the coastal settlements of Hector and Ngakawau (north of Westport) self-evacuated, with one property inundated with seawater. On 11 August, strong winds in Auckland tore part of the roof off The Cloud on Queen’s Wharf. Ports of Auckland reported 20 shipping containers were knocked over by the wind. On 12 August, several tornadoes were reported in Taranaki. A trampoline hit a car on Devon Rd (SH3) just north of New Plymouth. On nearby Paraite Rd, 40-year old trees were brought down with roofs torn off several buildings, and a woman suffered a broken collarbone after being blown into a wall. A tornado was observed in south Taranaki, causing damage to a power pole on Oeo Rd near Opunake. Later in the evening, a thunderstorm struck central Auck- land’s waterfront, with reports of a tornado there. Trees were shredded of their branches and metal construction fencing had been brought down. A shipping container was blown onto a car at Jellicoe Wharf, trapping and injuring the driver. Several yachts lost their moorings at Westhaven Marina, and a catamaran was overturned, with significant damage reported to nu- merous recreational vessels.

Snow and ice June 1st, the first day of meteorological winter, started on a chilly note with snow falling in the South Island and in the Central Plateau. Arthur's Pass to Springfield (SH73) and Lewis Pass between Hanmer Springs and Springs Junction (SH7) were closed due to heavy snow. Two people were temporarily stuck in their car on a remote section of SH8 between Burkes Pass and Kimbell as rockfalls and snow closed main thoroughfares. Another vehicle was stranded for more than four hours in a snow-filled ditch on the highway between Geraldine and Fairlie in Canterbury. On 4 August, snow fell to sea level in southern and western parts of the South Island, and to approximately 300 metres above sea level in Dunedin inland parts of Otago. Snowfall was reported in Greymouth, Hokitika, Kumara, Moana, Runanga and Serpentine Beach, which is a particularly uncommon occurrence in those places. The prevailing southwesterly flow during

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 10 this event meant southern parts of Southland and South Otago received the heaviest snowfalls. There were a raft of road closures due to snow throughout the country from 4-5 August, including the Desert Road (SH1), Takaka Hill road (SH60), SH7 between Reefton and Springs Junction, the Lewis (SH7) and Lindis (SH8) Passes, the Crown Range road between Queens- town and Wanaka, Dunedin to Waitati highway (SH1), SH1 between Clinton and Milton, SH93 between Clinton and Mataura, SH8 from Milton to Lawrence and about Raes Junction, and the Milford Road (SH94). On 10 August, snowfall closed Burkes Pass (SH8) between Fairlie and Tekapo, and Arthur’s Pass (SH73). Large accumulations of new snow were reported at several ski areas including Broken River and Craigieburn (50 cm), and Temple Basin (63 cm). Particularly heavy snowfalls were reported in Arthur’s Pass and Mount Cook Villages.

Lightning and hail On 5 June, the Sky Tower in Auckland was hit by a lightning strike as thunderstorms bat- tered the region. Northland recorded 3200 lightning strikes and a microburst caused damage in Coopers Beach in the Far North as roofs where ripped from buildings and caravans were flipped. One couple suffered minor injuries. On 13 July, a family outside of Aranga, Northland was left shaken after their car windscreen was struck by a lightning strike. Fortunately the family was left unharmed. On 14 July, over 5500 lightning strikes were recorded over central New Zealand and two Air New Zealand flights, one from Wellington to Dunedin and one from Hamilton to Wellington were struck by lightning. On 11 August, thundery weather brought strong winds and heavy rain in parts of Auckland. Five homes in St Heliers had damaged roofs, while a home in Ku- meu was struck by lightning. Over 700 lightning strikes were recorded over western and inland parts of the upper North Island during a one-hour period during the evening

Cloud and fog On 13 June, fog caused domestic flight delays and cancelations out of Auckland and Queens- town Airports. Also, low visibility caused a multi-vehicle crash that blocked southbound lanes of the Southwestern Motorway, near the Dominion Rd on-ramp in Auckland. On 14 June, for the second consecutive day, fog blanketed parts of Auckland city causing 59 flight cancellations and 40 delays out of Auckland Airport. Fog caused disruptions at Auckland Airport on the 10th,11th, 22-26th and 30th of July.

=-======NOTABLE WEATHER IN NZ: WINTER 2019 (Ben Tichborne)

June began with some stormy weather, but then became more settled. Both July and August were typically changeable months, and while July was unusually mild, August saw more typi- cal winter temperatures with some colder outbreaks.

JUNE 1st/2nd – Cold southerly outbreak over NZ. Snow on high country, but also reaching down to 200-300m on Canterbury Plains. Heavy rain causes some surface flooding in parts of Christ- church on 1st, while runners in the city’s marathon the next day are lashed by rain and hail showers. Snow closes SH73 through Arthurs and Porters Passes and SH7 at Lewis Pass on 1st, and SH1 the Desert Road on the 2nd. 3rd – Frosty start to the day in wake of previous few days of cold southerlies, eg -9C minimum at Lake Tekapo 5th – Storm lashes parts of North Island. (see details below) 12th – Some heavy rain in southern Hawkes Bay, eg 63mm in Dannevirke. 13th – Fog and low cloud causes disruption in Auckland, including forced cancellation of flights from the airport and resulting in a multi-car crash on the southwestern motorway.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 11 Fog also causes disruption at Queenstown Airport. Unusually mild day on South Island West Coast, due to fohn easterly flow, eg 20C maximum at Arapito (new June record), and 17C in Greymouth. 14th – Unseasonably warm in western parts of Central NZ in a mild easterly flow. Highs in- clude 20C in Appleby, 19C in Porirua, Richmond, and Nelson, 18C at Farewell Spit, and 17C in Westport. Mild overnight minimums of 13C in Palmerston North and Porirua. Fog causes disruption at Auckland Airport for a second day. 17th – Snow showers about the hills (as low as about 350m) in Otago and Southland. 26th-30th – Anticyclonic conditions over NZ, with fine settled weather in most places, though with widespread frosts. However, freezing fog in parts of Central Otago suppresses daytime temperatures there, eg Alexandra reaches no more than 0C for three days from the 26th.

JULY 3rd – Unseasonably warm temperatures in many areas under a northerly flow. Dunedin (20C) and Ranfurly (17C) record new record high July maximums, while Whanganui reaches 19C. Highs reach 20-21C in some places in Canterbury, while Ohakune rise to 16C. 4th – Active trough with moist northerlies brings heavy rain and gales to central and northern North Island. New July record 84mm recorded in Taupo; Waiouru records 61mm. The wind causes some damage in Auckland. Unusually high overnight minimums (as high as 16C-17C) in north of North Island, with several July records broken. However, cold southerlies spread over South Island with some snow on the high country. 5th/6th – Cold south to southwest flow over NZ, with snow showers on the high country. Desert Road closed in the early hours of the 5th. 7th – Heavy frosts in some sheltered areas in alight southwesterly flow, eg -6C minimum in Clyde. 10th – Heavy sea fog causes disruption in Auckland. 11th – Second day of heavy fog causes more disruption at Auckland Airport. 12th – Tornado causes some damage in New Plymouth. 13th – Heavy rain in Fiordland, eg 126mm at Milford Sound, and 48mm at Manapouri. Thun- derstorms reported about Southern Alps and Northland. 14th – Active cold front crossing North Island brings heavy rain to north and west of island, plus Wellington region. (where there is surface flooding) Thunderstorms about central NZ, with some 5500 lightning strikes recorded. The rain is accompanied by northwesterly gales, with some damage reported in parts of Taranaki, and a campervan blown over near Te Haro- to on the Napier-Taupo Highway. 16th – Snow closes the Lewis Pass for a time. Ice causes problems on roads in the Mackenzie Country and the Lindis Pass. 25th – Heavy rain on Coromandel Peninsula. 28th – Heavy rain on South Island West Coast, eg 117mm in Hokitika, and 63mm at Secretary Island. 30th – Fog causes disruption at Auckland Airport. 31st – Cold southerly over South Island, spreading over North Island during afternoon and evening. Snow down to about 300m in North Canterbury. Hailstorm gives parts of Auckland a snow-like blanketing.

AUGUST 1st – Cold south to southwest flow over NZ, with some snow showers on the high country. 2nd – Very strong west to southwest flow over NZ, with cold front crossing the country. Gusts reach 161 km/hr at Secretary Island, and 69 km/hr in Clyde. Strong winds force a plane to make two attempts before landing at Napier Airport. Fresh snow on South Island high country. 4th/5th – Very cold outbreak with snow in west and south of South Island. (see details below) 8th – Brief heavy falls of rain in Auckland area.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 12

10th-12th – Heavy rain, gales, and South Island snow. (see details below) 17th – Heavy rain causes surface flooding in Levin. Some thunderstorms around Auckland. Cold southerly spreads over South Island, with snow down to about 300-400m in places. 18th – Cold southerlies affect eastern areas, with some light snow on the high country. Cloud cover extending from the north results in a chilly day in some northern areas, with West- ern Springs, Auckland reaching only 9C. 20th – Heavy rain causes surface flooding on Auckland’s North Shore, especially in Devon- port. 22nd – Thunderstorms affect Northland, Auckland, and Coromandel Peninsula. In Auckland, the storms are accompanied by hail, while some 50 lightning strikes are recorded in one hour. Flooding affects the Sylvia Park Mall. 26th – Some thunderstorms in southwest of North Island.

MAJOR EVENTS

5th June – Storm lashes parts of North Island

A low with associated fronts brought a period of stormy weather to many parts of the North Island on this day.

The low, which formed in the western Tasman Sea the day before, had moved to lie just to the west of the North Island by midday on the 5th. A warm, then a cold front on its eastern side moved down the North Island with a period of heavy rain and thunderstorms, plus winds reaching over gale force in many areas.

The winds caused damage in several areas. Downbursts (reported in the media as tornadoes) damaged some properties at Cooper’s Beach, Northland, and near the Kaipara Har- bour. Northland reported 3200 lightning strikes, while lightning also struck Auckland’s Sky Tower. Some 1000 households lost power in the Bay of Plenty, while the poor conditions caused disruption at Auckland Airport.

The low moved away to the east of the North Island, with a south to southwest flow over the island, by the early hours of the 6th.

Mean sea-level analyses for noon and midnight NZST 5th June tare shown here.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 13

4th/5th August – Very cold outbreak with snow in west and south of South Island

After an unusually mild July, colder conditions set in from the end of the month. However, on the 4th/5th, it became very cold with a strong southwesterly flow sweeping over NZ, bringing snow to low levels in the west and south of the South Island.

A cold southwesterly flow already covered the country by early on the 4th. Very cold air moved onto the far south during the early hours, with snow lowering to and settling at sea- level in Southland and South Otago, including Invercargill. Several roads were closed. A cold frontal disturbance brought the air further north over the island during the day. As the flow was southwesterly, the shower activity and moisture affected the west rather than east coasts. Snow fell to sea-level in Westland, with light falls even settling on beaches, a very unusual occurrence. Falls also reached low levels further north in Kahurangi and Golden Bay ranges. Daytime highs were very low, with new August records broken at Nugget Point (1C), Balclutha (2C), and Haast. (4C) Other low maximums included 1C at Manapouri, 3C at Milford Sound, 4C in Hokitika and Reefton, and 7C in Greymouth. By contrast, Canterbury remained largely dry, with little or no snow falling to low levels.

By the evening, this cold airmass moved onto the North Island, with snow to low levels about the central high country. (the Desert Road was closed) By the morning of the 5th, dustings of snow were recorded as far north as Mamaku and Mt Ngongotaha, near Rotorua.

The flow gradually eased during the 5th. However, further snow showers continued to low levels in Southland, with some lighter falls extending into South Otago and Dunedin for a time.

Mean sea-level analyses for midday NZST 4th August to midnight NZST 5th August in 12-hour steps are shown here.

10th-12th – Heavy rain, gales, and South Island snow

A deep and complex low pressure system brought stormy weather to large parts of NZ during these three day, with heavy rain, gales, thunderstorms, and snow in inland South Island.

A large, deep and complex low was situated in the South Tasman Sea on the 10th, moving only slowly towards the South Island on the 11th. The weather was unsettled and wet in most areas of NZ, though the North and South Island were affected in different ways.

Fronts crossed the North Island, bringing spells of squally winds, thunderstorms and heavy rain to northern and western areas, as well as the top of South Island. Surface flooding resulted from one storm in the southern coastal suburbs of Wellington on the 10th. The next day, more than 700 lightning strikes were recorded in the upper North Island. A home in Kumeu was struck by lightning, while homes in St Heliers and the Cloud on Queen’s Wharf were damaged by wind gusts.

In the South Island, cold undercutting air brought rain to eastern areas, with snow inland down to about 300m. The snow closed SH73 through Arthurs Pass and SH8 between Fairlie and Tekapo. Heavy snow dumps were recorded on several ski-field, eg 63cm at Temple Basin and 50cm at Craigeburn. The heaviest rain affected parts of South Canterbury and eastern Otago, with flooding in places. SH1 between Oamaru and Timaru was closed for a time. Oama- ru recorded 78mm on the 10th (a new August record), with 83mm Waimate on the same day.

On the West Coast, while heavy rain fell on the 10th (when Greymouth recorded 84mm), temperatures were milder than normal thanks to the fohn effect of the easterly flow. Greymouth reached 19C on the 11th, a new August record high.

On the 12th, the low dissolved into a complex trough as it moved over NZ. Conditions eased over the South Island, but the unstable northwesterly flow continued over the North Island, with some more fronts.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 15

Mean sea-level analyses for midday NZST 10th August to midnight NZST 12th August in 12-hour steps are shown here.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 16 Rain, snow, and strong winds kick off long weekend 1 JUNE The wild weather is putting on a show for the first day of winter, with gale force winds forecast throughout the country and significant snow and rain for Canterbury and Marl- borough. Residents woke to snowfall in Lake Tekapo today. Source: Ava Gardner/ Supplied The meteorological service said an active low pressure system is moving up the east of the country today, before moving further away to the east tomorrow. Snow has been reported as low as 300m overnight to areas such as Methven, MetService said on Twitter, adding, "Winter, officially and literal- ly has arrived!" https://www.tvnz.co.nz/one-news/new-zealand/rain-snow-and-strong-winds-kick-off-long- weekend

Snow adds to Irishman Creek festivities in Fairlie 2 Jun Snow did not hold back more than 170 participants from a tradition dating back to 1956. The colder weather in Fairlie only added to the excitement at the 65th Irishman Creek Rally with vintage cars causing very few problems, organisers say. Abridged.

BEJON HASWELL/ STUFF Pre-1930s cars braved the fresh winter snow in Fairlie for the 65th Irishman Creek Rally on Saturday. https://www.stuff.co.nz/ timaru-herald/ news/113191530/snow-adds- to-irishman-creek-festivities- in-fairlie

South Island endures mixed start to winter as cold snap continues to bite 2 June South Islanders battling to stay warming during the long weekend can expect no relief from the days ahead. About 90mm of rain has lashed Christchurch since Friday morning, leaving roads flooded and the Avon and Heathcote rivers bursting their banks in some places.

JOSEPH JOHNSON/STUFF: Heavy rain in the Christchurch area since Friday morning left many parts flooded, with people left to wade through streets in Kaiapoi.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 17 In Christchurch around 4000 runners endured wet and blustery conditions as they took part in 10km, half marathon, marathon and children's events. Despite the rain in Christchurch, MetService forecaster Kyle Lee said the general trend was one of easing weather for most of the South Island. More than 40 hours of rain has left many areas flooded, particularly around Canterbury. https://www.stuff.co.nz/national/113187858/ south-island-endures-mixed-start-to-winter-as- cold-snap-continues-to-bite

Snow affects roads and rain, strong winds arrive for holiday weekend

2 June MetService says about five centimetres of snow fell on the Desert Road overnight, however, the main highway is now open again.

Snow around the Desert Road at 7.21am on Sunday 2 June. Photo: NZTA MetService meteorologist Kyle Lee said it was likely to stay cold for much of the Queen's Birthday weekend before warming briefly in the North Island on Tuesday. https://www.rnz.co.nz/news/ national/391014/snow-affects-roads- and-rain-strong-winds-arrive-for- holiday-weekend

Winter snow brings fun for children and skiers in Taranaki 2 Jun 02 2019 Mt Taranaki turned white at the weekend, and while the sight was welcomed by young- sters and skiers, the snow is not sticking around. Instead, the first week of the Taranaki winter will carry on as it began - with severe rain, a Met Service meteorologist warned. Stratford Mountain Club president claims they were the first skifield in New Zealand to be ful- ly operational this year, as those who opened on Saturday only had learners' slopes open.

JOHN VELVIN/STUFF:The first large snowfall of the year was enjoyed by all. Met Service meteorologist Tamara Vuska said while everyone was enjoy- ing the snow https://www.stuff.co.nz/taranaki- daily-news/news/113192265/winter- snow-brings-fun-for-children-and- skiers-in-taranaki

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 18 Welcome to winter: Queen's Birthday polar blast good news for New Zealand's skifields

4 June Skiers and boarders enjoy an early dust- ing of snow in Happy Valley on Whakapa- pa, Mt Ruapehu, on Sunday. Photo / Sup- plied NZ Herald A polar blast welcomed winter over Queen's Birthday weekend, allowing some to dust off the skis before backing off just enough for a sunny end in the upper North Island. https://www.nzherald.co.nz/nz/news/ article.cfm?c_id=1&objectid=12236925

Kaiwaka family 'devastated' as tornado tears through shed

5 June

A family who moved north of Auckland for a better life have been left "devastated" after a tornado tore through a shed housing all their belongings while they made the move to the countryside. Kellie and Matthew Chisholm moved to Kaiwaka from Auck- land in December last year for a "better life". The couple have a house being built offsite, but have been living in a motor home with their belongings stored in a shed on their new https://www.tvnz.co.nz/one-news/new-zealand/kaiwaka-family-devastated-tornado-tears- through-shed-storing-their-belongings-after-moving-auckland-better-life

Raw video shows caravan flipped onto roof as tornado hits Far North beach settlement 5 JUN

A caravan has flipped onto its roof after a tornado hit a North- land beach settlement. About a dozen properties at Cooper's Beach in the Far North have suffered damage due to the wild weather that's battering the North Island.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 19 NIWA meteorologist Chris Brandolino said the thunder, lightning and heavy rain is expected for the next few hours over the North Island. In New Zealand, tornadoes are primarily caused by a type of storm known as pre-frontal squall lines, which NIWA explains are "bands of thunderstorms embedded in a strong, unstable pre-frontal northwesterly flow". If you're outside and see a tornado, trees should be avoided at all costs - and you should try and find a ditch or a gully to lie in. It is best to protect your head with an object if possible. Abridged https://www.tvnz.co.nz/one-news/new-zealand/raw-video-shows-caravan-flipped-onto-roof -tornado-hits-far-north-beach-settlement https://www.newshub.co.nz/home/new-zealand/2019/06/watch-terrifying-moment- tornado-attacks-far-north-settlement.html

NIWA to provide window beneath Rotorua Lakes and streams at Fieldays

5 June, Visitors to NIWA’s stand at this year’s Fieldays are invited to go diving with into the Rotorua lakes -without having to get wet. http://www.voxy.co.nz/national/5/340050

Warmest autumn ever, climate scientist says 6 Jun

A lone trout fisherman winds-up for a cast out onto Lake Tarawera, near Rotorua, amid balmy weather on May 23. Photo / Alan Gibson New Zealand's official climate agency has just declared autumn the fourth warmest on record. But by one climate scientist's model, which combined sea temperatures as well as those on land, the autumn of 2019 took the top spot as the hottest on the books. Professor Jim Salinger made that calculation, suggesting the warmest autumn in more than 150 years of records, partly based on a temperature series he assembled featuring 11 stations in the North Island and another 11 in the South Island. When recordings from the seas around New Zealand were factored in to make a wider model, the March to May period came in at 1.2C above average, or the warmest ever, Salinger said. He clarified that these would differ from Niwa's figures, as the agency used a seven-station series to compile its summaries. https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12237865

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 20 Weather: Wild winds whip up giant west coast waves

8 June

Strong winds lashed the North Island, causing giant waves - some as big as seven metres. Boaties and fishers were advised to avoid the water or fishing on rocks in the west, with the dangerous surf nearly wiping out one group of sightseers who dared to walk the rocks at Auckland's Muriwai beach.

https://www.newshub.co.nz/home/new- zealand/2019/06/weather-wild-winds-whip-up- giant-west-coast-waves.html

Waimate District Council will not sign climate change emergency declaration 9 Jun

MYTCHALL BRANSGROVE/ STUFF: High tides are contrib- uting to erosion at Timaru's Patiti Point. (File) Waimate District Council is not going to follow the lead of other councils and sign a climate change emergency declaration, with its mayor say- ing there is little value in buying into an agreement with no clear objectives or goals. The Local Government Lead- ers' Climate Change Declara- tion says climate change presents "significant opportunities, challenges and risk to communi- ties throughout the world and New Zealand" and that local and regional government under- take a "wide range of activities" that will be impacted by climate change. Timaru District Council chief executive Bede Carran confirmed the council had decided to sign the declaration. Mackenzie mayor Graham Smith said his council had committed to signing the declaration. "We do acknowledge that climate change is going on, there are more floods and more extreme weather and we are putting $300,000 aside each year for extraordinary Abridged https://www.stuff.co.nz/timaru-herald/news/1132\4055/waimate-district-council-will-not- sign-climate-change-emergency-declaration

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 21 Holey Moley 11 June HUGE holes in Antarctic sea ice have been appearing for weeks at a time – and scientists may finally know why. The gaps, which can each cover an area larger than Switzerland, are caused by wicked weather conditions and underwater vortexes, according to a new study.

Whale-shaped hole in sea ice offshore of the Ant- arctic coast as seen by a NASA satellite on Sept. 25, 2017. It measured 19,000 square miles Experts have known about the mysterious ice holes, called polynya, for decades. They stick around for weeks to months, where they act as an oasis for penguins, whales and seals to pop up and breathe.

Researchers found that several factors play a key role in polyna formation – but all must be present at once. High wind speeds during heavy storms push ice around and force upward mixing of the water in the eastern Weddell Sea. In that region, an underwater mountain known as Maud Rise forces water around it and leaves a spinning vortex above. Analysis shows that when water at the surface is especially salty, strong winter storms can set off an overturning circulation. Warmer, saltier water from the depths gets churned up to the surface, creating a feedback loop where ice can't reform. The study was published in the journal Nature. Abridged https://www.thesun.co.uk/ tech/9261234/mystery-ice-holes- antarctic/

Auckland fog: Relief after 66 flights cancelled, traffic delayed in morning mayhem

13 June Fog restrictions have been lifted at Auckland Airport after dozens of flights were cancelled and delayed. The heavy fog also caused problems for commuters on the South-Western Motorway, where two sepa- rate crashes blocked lanes.

LALIT RANE/SUPPLIED: The Sky Tower peeps out from a blanket of fog which covered Auckland City on Thurs- day morning. https://www.stuff.co.nz/travel/travel-troubles/113443775/flights-delayed-due-to-auckland- fog

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 22

NZ's new role in global Tropical Cyclone preparedness 14 June 2019 The World Meteorological Organization (WMO) has named Chris Noble from New Zealand’s MetService as the Chair of the Tropical Cyclone Committee for the South Pacific and South- East Indian Ocean. The Committee is one of five regional bodies charged with coordinating activities to ensure that the loss of life and damage caused by tropical cyclones globally is minimised through effective warning systems and international coordination and cooperation. Looking forward, Chris Noble says that the Committee’s role becomes even more important as the impacts of climate change hit. “I’m honoured to lead this Committee and continue its important work which covers a total of 21 countries including Indonesia, Papa New Guinea, Australia, New Zealand and all other South Pacific nations. Peter Lennox, Chief Executive of MetService says the national meteorological organisation has a proud association with the Tropical Cyclone Committee. Steve Ready, a former MetService employee who retired in 2014, was the chairperson for the Committee for an unprecedented 16 years. http://www.scoop.co.nz/stories/SC106/S00021/nzs-new-role-in-global-tropical-cyclone- preparedness.htm

More than 1200 Invercargill and Bluff homes at risk from sea level rise 14 June

ROBYN EDIE/STUFF An aerial view of part of Invercargill. (File photo) Invercargill appears to be in the firing line when it comes to climate change with more than 1200 homes and 13 critical facilities in Invercargill and Bluff already at risk of ris- ing sea levels. Local Government New Zealand says councils have to take climate change seriously as they future proof. Insurance Council of New Zealand chief executive Tim Grafton said according to preliminary research from NIWA, there are 125,600 buildings and $38 billion of replacement costs within 0-1m of sea level rise nationwide and there is near certainty that the sea will rise a further 0.2m to 0.3m in the next 20 years. The council has considered climate change when developing asset management plans and other core documents such as the District Plan, Annual Plan and Long-term Plan. Abridged https://www.stuff.co.nz/southland-times/southland-top-stories/113307717/more-than- 1200-invercargill-and-bluff-homes-at-risk-from-sea-level-rise

MetService to upgrade forecast on website 15 June

After years of complaints that weather forecasts for the West Coast are putting off visitors, the MetService has confirmed a series of changes intended to narrow down its forecasting. The refreshed web site will also list forecasts under the "towns and cities" tab for Westport, Reefton, Greymouth, Hokitika, Franz Josef Glacier and Haast.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 23 MetService communications meteorologist Lisa Murray said yesterday the website, which until now has shown only Greymouth, would be refreshed to show two West Coast locations a "decent distance apart". Forecasters were also being advised to split the forecast when applicable. MetService would continue to issue two regional forecasts for the West Coast - one for Buller and one for Westland, "with forecasters being advised to split the forecast by landmark when applicable". https://www.odt.co.nz/regions/west-coast/metservice- upgrade-forecast-website

New Zealand scientists to launch world-leading climate change study in Antarctica 19 Jun

The ice sheets of Antarctica and Greenland may collapse even if we limit global warming. An expedition to study the ocean around Antarctica and its impact on climate change has been given the green light. ‘Antarctic ocean mechanics: past, present and future' is a six year programme that will be led by the National Institute of Water and Atmospheric Research (NIWA). It is one of several long-term Antarc- tic research projects that will be undertaken by New Zealand scientists following a $26 million investment announced by the Antarctic Science Platform today. https://www.stuff.co.nz/environment/113601379/new-zealand-scientists-launch- worldleading-climate-change-study-in-antarctica

Think today was cold? Looking back on NZ's coldest day 19 June

Blacks Hotel at Ophir, at the centre of a hoar frost in 2007. PHOTO: GERARD O’BRIEN New Zealanders shivered through the year's coldest morning today, but few will have experienced the kind of crushing cold of the country's lowest recorded temperatures. the inhabitants of Ranfurly in Cen- tral Otago in mid-July 1903 truly suffered when the thermometer plunged to -25.6C, New Zealand's lowest recorded daily minimum. There were cases of frostbite, bottles froze and burst at pubs, town water supplies were at risk - and copies of the Mount Ida Chronicle stuck together when they were being printed. It reported that on Friday, July 17, 1903, "the thermometer registered 4 deg below zero [Fahrenheit, -20C] at Naseby and Gimmerburn, while it went down as low as 14 deg below

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 24 zero [-25.6] at Ranfurly. This is the most intense cold experienced in that district since it was settled. New Zealand's five lowest daily minimum recorded temperatures: • -25.6C, Ranfurly, Central Otago, July 17, 1903 • -21.6, Ophir, Central Otago, July 3, 1995 • -21C, Omarama, 26km south of Twizel, June 24, 2015 • -19.8, Pukaki Airport, near Twizel, June 23, 2015 • -19.7C, Ophir, 1943

The Great Snow of 1939 in Dunedin. Photo from 'The Evening Star' archive. On July 31, 1939, the lighthouse keeper at Cape Maria Van Diemen, about 6km south of Cape Reinga, reported a fall of snow, the first recorded there. Aucklanders woke to white scenes on Thursday July 27, 1939 after an overnight snowfall. Another big snow year was 1930, when, according to weather historian Erick Brenstrum, writing in New Zealand Geographic, bad weather followed a Lions rugby tour around the country and "snowflakes were seen in Onehunga and Karangahape Rd on July 28". https://www.odt.co.nz/regions/think-today-was-cold-looking-back-nzs-coldest-day

Less is more: Small but 'superb' 2019 vintage good news for NZ's wine reputation 21 June A warm summer has contributed to a small but "superb" harvest in New Zealand wine regions. The harvest was smaller than originally thought, but what was harvested was better quality than previous years, said viticulturist James Bowskill. "We had less rain for a good part of the summer which meant the fruit was nice and clean," he said.

SCOTT HAMMOND/STUFF: This year's harvest is 6000 tonnes smaller than last year. https://www.stuff.co.nz/business/113628445/less-is-more-small-but-superb-2019-vintage- good-news-for-nzs-wine-reputation

Winter solstice: Our days will slowly get longer, but mornings lag - why? 21, Jun

Depending on where you live the winter solstice - the official start to the astronomical winter season - will mean your day will be light for just 8 hours and 35 minutes at the least, and 9 hours and 46 minutes at the most on Saturday June 22. But don't think long, warm days are just around the corner - it will be a slow, cold few weeks until we notice any difference.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 25 "The longest days will be found in Northland and the shortest in the far south - Stewart Island," Over the eight days following the solstice, sunrises around the country will be one minute later and sunsets three minutes later, due to the solar noon. https://www.stuff.co.nz/ national/113664846/winter- solstice-our-days-will-slowly-get -longer-but-still-start-later--why

Brrring on the weekend! Chilly weather to last to Sunday

26 June

The chilly temperatures will likely last until the weekend. Photo / File MetService meteorologist Tamara Vukfa said the icy temperatures were the result of longer nights throughout the winter months, with the chilliest time hitting just before sunrise. The country was currently under a ridge of high pressure with no cloud. This meant the days were clear with little cloud, but any warmth from the Earth ra- diated into the air during the long nights. https://www.nzherald.co.nz/bay-of-plenty-times/news/article.cfm? c_id=1503343&objectid=12243930

Niwa and council to run year-long study into Picton air quality 27 Jun

Standing under the new air quality monitoring station from left, Te Ātiawa Trust rohe management Ian Shapcott, Niwa atmospheric techni- cians Tony Bromley and Sally Gray, Port Marlborough Rose Prendeville, Marlborough Sounds councillor Da- vid Oddie, Council environmental scientist Sarah Brand and Guardi- ans of the Sounds chairman Paul Keating.

The quality of Picton's air is to be monitored in a year-long study, after a "strong push" from residents concerned about ferry fumes and pollution. Council and Niwa have installed meteorological stations and air quality transmitters around Picton and are set to begin a year-long study into its air quality.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 26 The transmitters will record air quality through a winter and summer, operating from July until the end of winter 2020. This comes after people in the Marlborough Sounds expressed their concerns last year, over what shipping fumes were doing to their health.

CHLOE RANFORD/STUFF A view of Picton shows the "steep-sided narrow valleys" which Marine and environmental engineer Brent Yardley says traps emissions close to the water. Niwa atmospheric technician Tony Bromley said it was "complex terrain" to conduct the monitoring. "You've got valleys, you've got hills, you've got the water, the Sounds. "We need to know the air flow to know where the pollution is coming from, the worst areas and where it's being taken to." Recent developments around MARPOL, an international treaty to reduce ship emissions, meant port towns were in the "forefront", Council's environmental scientist Sarah Brand said. https://www.stuff.co.nz/environment/113813584/niwa-and-council-to-run-yearlong-study- into-picton-air-quality

Queenstown's snow drought: Skifields relying on snowmaking

30 June

Skifield operator NZSki remains confident it can keep Coronet Peak and The Remarkables topped up with snowmaking. Photo / Supplied AlliedPress Queenstown's ski season faces an uphill struggle with little or no natural snow on the horizon. But skifield operator NZSki remains confident it can keep Cor- onet Peak and The Remarkables topped up with snowmaking. Due to unusually dry conditions, "there is less snow than normal at this time of year". https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12245209

Long, dry spell pleases South Canterbury farmers 2 July June is on track to be the driest in South Canterbury since records began - and the long stretch of dry weather has been welcomed by farmers.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 27 Last month, the MetService's weather station recorded only 18.2mm of rainfall, about half the monthly average. This included a rain event which saw 17.2mm fall on June 1 alone. MetService forecaster Kyle Lee said the dry spell was largely down to settled weather patterns across the country."We saw a lot of large high pressure patterns across the country, especially in the South Island, and it meant it was particularly settled towards the end of June," Lee said.

BEJON HASWELL/STUFF https://www.stuff.co.nz/timaru-herald/news/113920555/long-dry-spell-pleases-south- canterbury-farmers

Driest first half of year on record 03 Jul, 2019

A Niwa scientist says Auckland, Hamilton, Whangārei, Whitianga and Kaitaia have all had the driest first half of the year. - Photo: Twit- ter / NIWA Several locations around the country have experienced the driest first half of the year on record, and Watercare is calling on Auck- landers to use water wisely. Watercare said the Hūnua and Waitākere ranges, where its storage dams are located, had about 40 percent less rainfall than normal between January and June. A Niwa scientist, Chris Brandolino, said Auckland, Hamilton, Whangārei, Whitianga and Kaitaia have all had the driest first half of the year, with some places receiving less than half of the normal amount of rain. Abridged https://newsie.co.nz/news/155031-driest-first-half-of-year-on-record.html

'Sweet spot' brings Dunedin's warmest July day on record

4 July Dunedin basked in a weather sweet spot yesterday and recorded its warmest July temperature since records began. ''You're in a sweet spot just before a trough to the south and after that front that moved over yesterday, so you're sitting pretty compared to the rest of the country,'' meteorologist April Clark said about noon, as many city residents enjoyed lunch under the low winter sun.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 28

Basking under the low winter sun yesterday on the Union Lawn as Dunedin's winter made way for an unseasonably warm day are Otago Uni- versity biology student Kate Hacker (20, left) and geography student Jill Kirk (20), both of Minnesota, in the US. Photo: Gregor Richardson

https://www.odt.co.nz/news/dunedin/sweet- pot-brings-dunedins-warmest-july-day-record

Weather radar to be installed at Hindon 11 July 2019

A MetService weather radar, sim- ilar to this one in Northland, will be built near Dunedin next year. Photo: MetService Coastal Otago will be better equipped to act during floods with the arrival of a long- awaited $2.8 million weather radar. MetService confirmed yesterday it had this week signed an agreement with a Hindon landowner and hoped to begin construction of the device at the site in February next year. It planned to have the station operational by May. A location near the Taieri Plain was chosen as the area was particularly flood-prone. It is the tenth such radar to be installed in the country. https://www.odt.co.nz/news/dunedin/weather-radar-be-installed-hindon

Third day of fog for Auckland ahead of wet weekend for much of country 12 Jul There could be more transport woes for Auck- landers today with fog creeping over the city for the third day straight. It comes after fog caused 70 flights to be cancelled and nearly 80 delayed on Thursday, and But a front moving up the country today would bump the fog along, although it could hang around in places until mid-morning.

Whakatane River this morning. Photo / Katee Shanks Whakatāne experienced flooding with the rise of rivers in the area, with the exception of the lower reaches of the Whakatāne River.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 29 https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12246800 https://www.nzherald.co.nz/rotorua-daily-post/news/article.cfm? c_id=1503438&objectid=12248871

Lightning strike shatters windscreen of car in Northland 13 Jul

The damage done by a lightning strike to a car windscreen. Photo / Supplied A lightning strike shattered the windscreen of a car in Northland leaving the occupants shaken but uninjured. MetService meteorologist Andy Best said a "train of lightning strikes" passed across North- land's west coast at Baylys Beach between 12.45pm and 1.15pm yesterday. https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12249106

Lightning strikes across the country as foul weather strikes city centres 14 July 2019

A lightning strike, followed by rolling thunder, this morning in Wellington. (Image / Twitter) Lightning has struck a plane as the wild weather heading for Auckland batters the country. An Air New Zealand flight has been diverted to Christchurch after being struck by lightning, as foul weather strikes the country. NZ681 from Wellington to Dunedin was forced to land at Christchurch airport this morning, after encountering the strike. The strike was one of hundreds to hit the country today. According to MetService, in the North Island predominately around Welllington and Taranaki there have been 111 lightning strikes this morning, while in the South Island there have been about 1200 in the past 24 hours.

The latest MetService rain radar. Image / MetService

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 30 Wild and wet weather wreaked havoc this morning, flooding many parts of Wellington as the capital was hammered by gusts of up to 117km/h. https:// www.newstalkzb.co.nz/news/ national/deluge-lightning-and- thunder-strike-country-in- storm-moving-north/

Wild weather lashes country causing lightning strikes, power outages and fierce winds 14 JULY A spate of severe weather is causing carnage across New Zealand today as lightning strikes, power outages and gale-force winds cause havoc around the country. In the Hawke's Bay region, a campervan was flipped on its side on State Highway 5, blocking the southbound lane about two kilometres south of Te Haroto. No one was injured in the incident but police say high winds may continue in the "Windy Gap" on the Napier/Taupo Road.

In high winds, a caravan has flipped on the Napier/Taupo Road Source: Supplied Further north, Niwa have advised the Dar- gaville region to brace for severe weather as a deluge of rain and lightning is forecast. Their advice? "When thunder roars, head indoors."

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 31 Wild weather in Taranaki brings highway slip and power outages 14 Jul

JANE MATTHEWS: A landslip occurred just north of the Mt Messenger tunnel on Sunday, following a period of wild weather. Traffic was down to a single lane. The Met Service forecast showers with squally thunderstorms and hail for the rest of Sunday in the region. The region was forecast to receive a total of 57mm of rainfall by midnight Sunday. Abridged. https://www.stuff.co.nz/taranaki- daily-news/114226082/wild- weather-in-taranaki-brings-highway- slips-and-power-outages

Suggestions to help with SAD 16 July Written by Philip Duncan. Finding it hard to wake up in the mornings? Feeling a lack of energy? Feeling generally flat and down? You may be suffering from SAD - Seasonal Affective Disorder. SAD is quite normal to experience when our nights get long and the days short. For most of us experiencing SAD is only mild, we cope with it just fine. But for others the gloom of winter can really affect you in crippling ways, especially if it makes other issues feel even heavier and darker. Like depression, SAD can affect how you feel and behave for days, weeks or even months. When you are depressed, your low mood lasts, affecting your sleep, energy levels, relation- ships, job and appetite. The difference between depression and SAD is that if you experience SAD your symptoms will appear around the end of autumn, and continue through winter and until the days get longer and sunnier in early spring. You should not ignore SAD, as it can be effectively treated. For most of us, turning on a extra lights can make a really big difference. It's called Light Ther- apy. The few extra cents or dollars it may cost will be some of the cheapest and most effective therapy you can get for this. Put lights on during the day if gloomy or where you work - and switch on even more lights in your home as soon as you get home. It can work when you wake too, if you have to wake before the sun rises turn on lamps - Google "Light Therapy" for more info and to make it effective for you. Also, making the effort to brave the wintry weather, even if just for a vigorous 20 minute walk in the cold wind. http://www.voxy.co.nz/health/5/343230

Holidaymakers delighted with snowy Tekapo 17 July Tekapo woke to a winter wonderland on Wednesday morning as a flurry of snow hit the town. Tekapo sits at 720m and Clark said it lies within the southern areas where snow is expected. The snow also provided a winter wonderland for South Canterbury families staying in the Mackenzie township.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 32

Waking up to snow falling was an exciting holiday surprise for the Shaw family, of South Canterbury, who are staying in Tekapo for two nights, during the school holidays. https://www.stuff.co.nz/timaru-herald/news/114297239/ holidaymakers-delighted-with-snowy-tekapo

We're experiencing historically hot weather

19 July Last month was the hottest June ever, according to a new report from the National Oceanic and Atmospheric Administra- tion -- and it was the overall hottest first half of the year in South America, Mexico, New Zealand, Madagascar and other parts of southern Africa. “The bottom line is the Earth is one degree Celsius or 1.8 degrees Fahrenheit warmer today than the pre-industrial time period," said Brenda Ekwurzel, Director of Climate Science at the Union of Concerned Scientists. "What that means is that what used to be a rare hot day or high temp record is now the new normal for our summers.” June 2019 set a new record for hottest June ever. According to NOAA, the temperature across land and oceans was 1.71 degrees Fahrenheit above the 20th century average.

NOAA:This NOAA graphic shows land and ocean temperature percentiles in June 2019. - June marked the 414th consecutive month where temperatures were recorded as being above the 20th century average for that given month, according to NOAA. That’s a trend spanning more than 34 years. https://abcnews.go.com/US/statistics- show-experiencing-historically-hot- weather/story?id=64438226

Front after front': Wild week set to bring snow, downpours, gales 25 Jul 15

MONIQUE FORD/STUFF Surface flooding in Wellington on Sunday. More heavy rain is on the way for parts of the country overnight Mon- day. Another round of stormy weather is closing in, bringing snow to low levels, downpours, gales and possible tornadoes to some areas - and yet another battering from the ele- ments is due later in the week.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 33 More thunder and heavy rain are on the way for the west of the South Island, where some places at high elevations had 200mm of rain in 24 hours during the weekend, and where most of the 4500 lightning strikes over New Zealand in the 24 hours to 6am Sunday were concentrated. "Basically, it's just front after front after front. Each one is slightly different in nature," MetService meteorologist April Clark said. "Tomorrow is looking pretty active ... We've got in- stability there and also good moisture. That can produce heavy rain." https://www.stuff.co.nz/national/114240590/front-after-front-wild-week-set-to-bring-snow -downpours-gales

Explained: Why Auckland's been so foggy this week 25 Jul, 2019

Niwa meteorologist Ben Noll said this week's run of foggy mornings in the supercity had been "impressive". Photo / Brett Phibbs/Phibbs Visuals Aucklanders who have been staggering to work amid thick morning fog may get more of the same mist-making conditions for weeks to come. So what exactly is fog? We can think of it as a blanket of microscopic water droplets suspended in the air. These tiny water droplets scatter any light that passes through or past them, meaning objects in the fog become hard to see. Abridged. https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12252656

Heat streak: July to be our 30th straight month of higher temperatures 25 Jul,

New Zealand is about to mark its 30th straight month of above-average temperatures – some- thing a meteorologist has partly put down to climate change's "tail wind". Niwa also expected this month to be among the warmest Julys the country has experienced, in a year that's so far also been a near record-topper in the temperature stakes. Abridged https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12252784

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 34 Great snow of 1939: A world away from the weather today

29 July

One of Dunedin's most memorable snow events, the "Great Snow of 1939" brought the city to a shivering and prolonged halt. On the 80th anniversary of the polar blast, these photographs illustrate just how much snow there was. Niwa records show the severe snow- storm started in Dunedin on July 24, 1939, and lasted several days. Because of the amount of snow that fell in that time, it was considered a once-in-500-year event. It was one of many snowstorms to hit the region between June and August 1939, caused by frequent southerly outbreaks, and to this day the winter of 1939 is regarded as the worst for snow in living memory. Abridged. https://www.odt.co.nz/news/dunedin/great-snow-1939-world-away-weather-today

Cross about the coming cold snap? Blame it on negative SAM 30 Jul If you're looking to blame anything for the icy blast about to disturb what's been an otherwise pleasantly mild winter, point the finger at negative SAM. And no, that's not a gloomy individual named Sam who somehow holds sway over our weather, but an indicator that's long helped climate scientists predict the patterns prevailing over the country from one week to the next. MetService has just issued warnings for heavy snow in places in the South Island, with the white stuff accumulating at 400m in some parts. This switch was where the negative SAM – and in this case, it's extremely negative - came in. The SAM, or Southern Annular Mode, can generally be described as a ring of climate variability that encircles the South Pole, but stretches far out to the latitudes of New Zealand. First identified in the 1970s, it involves alternating changes in windiness and storm activity between the middle latitudes, where New Zealand lies, and higher latitudes, over the southern oceans and Antarctic sea ice zone. In its positive phase, the SAM is associated with relatively light winds and more settled weather over New Zealand latitudes, together with enhanced westerly winds over the southern oceans.

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 35

Source / National Weather Service Climate Prediction Centre It was a predominantly positive SAM that had contributed toward our past two unusually balmy summers, as well as two marine heatwaves that dramatically warmed up the oceans surrounding New Zealand. In negative phase, however, the westerlies increase over New Zealand, with more unsettled weather, while windiness and storm activity eased over the southern oceans. "The Southern Annular Mode is in the driver's seat here, there's no question about that – and it's doing everything we expect it to do in the negative phase, bring that cold, stormy, unsettled weather with rain and snow," MetService meteorologist Georgina Griffiths said. Learn more: https://t.co/GCyeKCPSqW pic.twitter.com/wBN3sVhCrR https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12254134

Auckland hailstorm leaves eastern suburbs covered in 'snow' 31 July

A hailstorm has rolled over parts of Auckland, leaving piles of "snow-like" hail around How- ick.

TESSA WORTHINGTON/SUPPLIED A 'hail'man that was built in Beachlands. https://www.stuff.co.nz/ auckland/114658543/auckland-hailstorm- leaves-howick-covered-in-snow

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 36 Blast of strong winds, hail, snow to strike New Zealand

31 July Kiwis should brace themselves for a tumultuous, cold end to the week, with damaging gusts of wind, thunderstorms, hail and low-terrain snow possible. " NIWA forecaster Chris Brandolino told The AM Show that a "weather crescendo" is beginning. "I see this evolving as a sort of weather crescendo, we start off, if you know music, you start off soft and light and then it grows and grows," Brandolino said. The blast will reach its peak in the weekend, according to Brandolino, with more cool gusts and possible low terrain snow on Sunday in Dunedin and Invercargill. Newshub. https://www.newshub.co.nz/home/new- zealand/2019/07/weather-bomb-blast-of-strong- winds-hail-snow-to-strike-new-zealand.html

Revolutionising ocean forecasting project launches 1 Aug

Whakatōhea Māori Trust Board, all of NZ’s Oceanographic institu- tions, with technology partner Zebra-Techand funders Ministry of Business, Innovation and Em- ployment. Photo by Simone Mag- ner. A bold new project that will rev- olutionise New Zealand’s ability to comprehensively measure, monitor and predict the state of our oceans, has been launched. New Zealand’s leading experts in oceanography joined MetService and Eastern Bay of Plenty iwi Whakatohea for the launch of the Moana Project at Omarumutu Marae in Opotiki. MetService’s chief executive Peter Lennox says the launch marks the initiation of the $11.5 million, five year research project, which is funded through the Ministry of Business, Innova- tion and Employment’s Endeavour Fund. The project, which was spearhead by MetService’s oceanography division MetOcean Solu- tions, will greatly enhance New Zealand’s understanding of our changing oceans. “The Moana Project will greatly advance understanding of marine heatwaves, ocean circulation, and connectivity, enabling us to better protect and manage the marine environment and its resource,” says MetOcean’s General Mamnager, Dr. Brett Beamsley. https://www.sunlive.co.nz/news/216644-revolutionising-ocean-forecasting-project- launches.html

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 37 July Equals or Surpasses Hottest Month in Recorded History, Says UN Chief

2 August United Nations: The latest data from the World Meteorological Organization shows the month of July "at least equaled if not surpassed the hottest month in recorded history" and it followed the hottest June ever, UN Secretary-General Antonio Guterres said on Thursday. Abridged https://www.news18.com/news/world/july-equals-or-surpasses-hottest-month-in-recorded -history-says-un-chief-2255223.html

Alone in a wild ocean, New Zealand gets smashed by some of the world's biggest waves 03 Aug

Far from any other piece of land, and sitting among some of the wildest wa- ters on the planet, New Zealand has some of the world's biggest waves. Massive seas hitting the south and west of the country this weekend show what can happen when conditions are right. And as is most often the case, it's the south and southwest of the country that's taking the biggest pounding, followed by the west coast. Ed Atkin, oceanographer at marine and freshwater consultancy eCoast, said the 8-11m in- shore waves forecast for Friday and the weekend were "very substantial" in the grand scheme of things. Much of New Zealand's wave climate was dominated by storm tracks around the globe in the Southern Ocean. "These storms generally generate the largest waves on the planet. and Starting with the biggest first. MetService subsidiary MetOcean Solutions measured a 23.8m giant at a buoy in the Southern Ocean during a storm in May 2018. Niwa reported that during a storm in June 2013, 15m waves were recorded at a buoy 2km off Wellington's Baring Head. They were the largest recorded at the buoy since measurements started in 1995, and Niwa thought they were likely to be the largest at that point in 50 years. During a big storm on Waitangi Day 2002, the biggest waves were 13m off Baring Head. Waves smashing into SH6 at Punakaiki were so big concrete was "thrown across" the road, in a storm in early 2018. The biggest storm to hit New Zealand in the 20th century is thought to have happened in Feb- ruary 1936. This was likely an ex-tropical cyclone, which "swept with cyclonic fury" through the North Island. "Phenomenal rainfall and extreme winds caused widespread damage and destruction of property throughout the North Island."

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 38 The Wahine storm of April 1968 is thought to have been the second biggest. And then there was the six-day storm of February 1868, which is also thought to have been an ex-tropical cyclone. KING TIDE According to the US National Oceanic and Atmospheric Administration,"king tide" is a non- scientific term often used to describe exceptionally high tides. Higher than normal tides typically happen during a new or full moon, and when the Moon is at the closest point to the Earth during its orbit of roughly 28 days. That closest point is perigee. About three or four times a year, when the new or full moon coincides closely with perigee, the tidal range is even bigger, although not by much. But at these times coastal flooding from a storm could be significantly worse than it otherwise would have been, hence the colloquial term “King Tide” https://www.stuff.co.nz/science/114711030/alone-in-a-wild-ocean-new-zealand-gets- smashed-by-some-of-the-worlds-biggest-waves

70cm of Snow in 72 Hours in New Zealand 3rd August 2019 After a slow start to the snow season, Ski areas have posted accumulations of up to 70cm in the past few and base depths have reached 3 metres (10 feet) at one area, the deepest in the southern hemisphere by more than a metre.

There have been some big snowfalls in New Zea- land over the past few days, transforming conditions after a slow start to the 2019 ski season there. More snowfall is expected over the coming week but with lighter falls and less extreme conditions. https://www.inthesnow.com/70cm-of-snow-in- 72-hours-in-new-zealand/

NIWA apologises for 5G weather 'confusion'

3 Aug Next-generation mobile networks won't interfere with forecasting in New Zealand, the national weather research agency NIWA now says. There were reports earlier this week 5G, rolling out later this year, would operate at frequencies that would interfere with satellites trying to track water vapour in the atmosphere. "When the satellite looks down it's looking for water vapour, and it might pick up 5G instead, so there's interference," NIWA climate scientist Nava Fedaeff told Newshub. If forecasters can't predict storms properly, that could put lives at risk. But NIWA says those concerns were based on World Meteorological Organization reports that 5G networks would operate at frequencies around 24GHz to 28GHz - close to water vapour sensors' 23.8GHz. "However, we understand that the planned 5G network announced by Vodafone uses lower frequencies of 3.5GHz and will not affect weather satellite technology in New Zealand," said Jochen Schmidt, NIWA's chief scientist of environmental information. "NIWA apologises for any confusion created." Abridged https://www.newshub.co.nz/home/new-zealand/2019/08/niwa-apologises-for-5g-weather- confusion.html

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 39 Rough seas continue to batter West Coast as wintry weather rolls on

4 Aug

Heavy seas continue to expose an old rubbish tip after a warning of an imminent ecological disaster on the South Island's West Coast yesterday. Hector Landfill experienced further erosion overnight and today but escaped any of its material being swept away. For residents of Hector, a seawall paid for by lo- cals has saved many properties during yesterday's high tide. Abridged. https://www.tvnz.co.nz/one-news/new-zealand/rough-seas-continue-batter-west-coast- wintry-weather-rolls-v1

Wild-winter conditions of snow, strong winds, showers and cold temperatures to continue 4 Aug

Windsurfer Alan McIntosh braved the strong winds on Lake Pupuke. Photo / Jason Oxenham Winter may have started off warmer than usual but we're starting to feel the bite now. New Zealand has been thrashed by nasty weather all weekend and it's set to continue. The polar blast which saw snow falling to sea level in the South Island slowly crept north- wards over the country. It's all part of a Southern Ocean storm that's smashed into New Zealand, bringing dangerous waves, gales and bitter cold. https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12255541

Weather: Residents calling snowfall biggest in 20 years

5 Aug Snowfall some residents are calling the biggest in 20 years caused havoc in parts of Otago and Southland on Monday. The storm forced the closure of a number of roads, and 73 schools and early childhood centres were also shut. Abridged

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it’s a bit nippy at our Gore testing station this morning #nzsnow http://www.meteo.pf/observation.php?carte=pfvdo

Storm brews as forecasters disagree

7 August While WeatherWatch is predicting an "enormous storm" to hit the South next week, the Met- Service and Niwa are calling the forecast premature.

NIWA: At this point, there is no need to be alarmed. There's a good chance it could be really far south of New Zealand, sparing the country of major impacts. MetService added that while there would be snow and rain with Monday's system, it would hit the usual high-country areas and was not likely to be any bigger than what shook the country last weekend. https://www.odt.co.nz/regions/storm-brews-forecasters-disagree

Auckland was hit by a fierce storm last night with more than 700 lightning strikes in an hour. 12 Aug The wild weather caused damage across the city, ripping up roofs and tearing down trees and powerlines.

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The Cloud event's centre on Auckland's waterfront had two roof panels lifted from it's structure. A resident in the east of Auckland says he was left shaken after his neighbour's roof was thrown into his backyard. "The rain just started and there was a mighty bang and the roof blew off and the doors blew in and all of a sudden totally exposed to this weather, it was just amazing." There were no injuries reported as a result of the weather. https://www.tvnz.co.nz/one-news/new-zealand/mighty-bang-auckland-man-describes- moment-neighbours-roof-ends-up-in-his-backyard-during-night-wild-weather? auto=6071703252001

Surf's up: Lyall Bay's biggest waves in 20 years

15 Aug Wellington surfers braved the cold wind and took to the water to ride the biggest waves in 20 years today.

Photo: RNZ / Jonathan Mitchell MetService said huge swells of up to five metres have been reported between the South Coast of the South Island and East Cape in the North. When word got out this afternoon, about two dozen surfers raced down to Lyall Bay and got into their wet suits. The waves were impressive - up to three-and-a-half metres - lapping the coast line and beach front. MetService said the huge swells are because of a southwesterly weather system and should ease in the coming days. https://www.rnz.co.nz/news/national/396786/surf-s-up-lyall-bay-s-biggest-waves-in-20- years

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Weather: 'Polar' conditions forecast for the weekend 15 Aug

A polar blast is forecast to hit the country over the next few days - again. Snow levels in Southland may be as low as 100m or 200m. In Otago, those snow levels are forecast to be about 200m or 300m - while Canterbury should have snow to 500m lowering to 300m later in the day, possibly to 200m for a time, Weather Watch said. https://www.newstalkzb.co.nz/ news/national/weather-warm- today-and-tomorrow-but-polar-conditions-forecast-for-the-weekend/

Pictures of devastation tearing through Auckland's Viaduct Harbour 19 Aug 18-meter catamaran cartwheels over the dock. "The wind speed they've estimated at 200 knots which is around 400km/h, so it was savage to say the least," boat own- er Andrew Stewart told Newshub.

The winds tore through last Monday night, leaving millions of dollars of damage along Auckland's waterfront. Abridged https://www.newshub.co.nz/home/new- zealand/2019/08/pictures-of-devastating-tornado- tearing-through-auckland-s-viaduct-harbour.html

Weather: Another 'big low' to bring thundery weather 19 Aug Thunderstorms, squalls, heavy rain and snow are back on the radar this week as another "big low" heads towards New Zealand. https://www.newshub.co.nz/home/new- zealand/2019/08/weather-another-big-low-to- bring-thundery-weather.html

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New Zealand glaciers won't survive this century, scientists say 20 Aug This week in Iceland, the country's first glacier to disappear was officially commemorat- ed and hailed a climate change tragedy, but New Zealand glaciers have also been declining for years without public outcry. Victoria University of Wellington PHD Student Lauren Vargo said when surveys started in the late 1970s, New Zealand had more than 3000 glaciers.

STEVE SHADWELL/SUPPLIED: The Franz Josef glacier in 2006. Most New Zealand glaciers have been rapidly declining since 2011. Both Franz Josef Glacier and Fox Glacier are no longer accessible by foot due to their re- treat. Vargo said how long glaciers would survive climate change depended on their location and size. A recent and unpublished study has found New Zealand's glacier areas reduced about 31 per cent from the late 1970s to 2016, Vargo said.

TALIA SHADWELL/SUPPLIED :The Franz Josef glacier in 2019. Estimates from international researchers show 74 per cent of the ice in New Zealand could be lost by the year 2100, she said. Niwa climate applications principal scientist Andrew Lorrey said if nothing changed globally, temperatures would continue to rise and the glaciers would continue to diminish. All 60 of Niwa's surveyed glaciers were "severely impacted" in the last two years," he said. Abridged. https://www.stuff.co.nz/environment/115135746/new-zealand-glaciers-wont-survive-this- century-scientists-say

New NIWA study shows 800,000 Kiwis at risk of flooding in coastal areas 22Aug A NIWA report released today predicts it will only take a 30cm sea-level rise for the risk there to become extreme. And that means coastal areas prone to floods, will see much bigger storm surges - the kind that would completely devastate the town.

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NIWA says 772,000 Kiwis are in danger of being flooded by the sea or a river, along with $147 billion worth of buildings, and 20 airports. The scientists say we should not be building new coastal developments, and local councils need to act fast to save those already there. https://www.newshub.co.nz/home/new-zealand/2019/08/new-niwa-study-shows-800- 000-kiwis-at-risk-of-flooding-in-coastal-areas.html

Weather: NIWA warns rare 'sudden stratospheric warming' to blast NZ with icy 'streamers'

23 Aug Winter is set to end with a biting cold snap, thanks to a freak atmospheric phenomenon that'll see temperatures over Antarctica rise more than 25C. Sudden stratospheric warming (SSW) events in the south have only been recorded twice in modern history, weather agency NIWA says, and both times saw temperatures in New Zea- land plunge. . NIWA says a SSW happens when the usual westerly winds in the stratosphere - 30 to 50km above the ground - reverse direction, disrupting the stable status quo. "In the Southern Hemisphere during winter, a ring of stormy and freezing weather encircles Antarctica," NIWA explains. "Known as the polar vortex, it is usually very good at keep- ing harsh, wintry conditions locked up close to the pole. When a SSW occurs, it can help to weaken or displace the polar vortex in the stratosphere, which then filters down onto the tropospheric polar vortex and influences our weather patterns." The weakened vortex can let off "polar air masses known as streamers" towards New Zealand for up to a month, said forecaster Ben Noll.

The stratosphere will be warm. Down where we are, not so much. Photo credit: NIWA SSWs more common in the northern hemisphere. That's because the Arctic is relatively

Meteorological Society of New Zealand Newsletter 158 Spring2019 Page 45 warm and is surrounded by colder land, while the Antarctic environment is colder and less volatile. "These events are rare in the Southern Hemisphere," said Noll. "There have only been two in New Zealand in recorded times: one in September 2002 and the other in September 2010." When an Antarctic SSW happened in 2002 it resulted in the coldest October in 20 years. Historic NIWA data shows it was on average between 2C and 3C colder than normal from Timaru in the south to Auckland in the north. Invercargill saw its second-highest rainfall on record, and hailstones the size of golf balls fell in Christchurch. https://www.newshub.co.nz/home/new-zealand/2019/08/weather-niwa-warns-rare- sudden-stratospheric-warming-to-blast-nz-with-icy-streamers.html

Chaotic weather system behind weirdly-shaped hail

23 August North Taranaki residents woke to a dramatic Monday, with a tornado, hail and high winds wreaking havoc across the region.

SUZANNE WALLWORTH SPIKY HAIL The spiky hail - some pieces several centimetres long - had a big impact in Taranaki on Monday, and there were other reports of irregularly-shaped large hail from Auckland and Wellington. MetService meteorologist Lewis Ferris said the strangely-shaped hail was new to him. It was thought that during the time the hail was falling there had been some melting and pieces of hail had collided, Ferris said. "They were in these strange-looking shapes because they had collided at some point." https://www.stuff.co.nz/national/114961652/chaotic-weather-system-behind- weirdlyshaped-hail

Rain, hail or shine: Forecasting the weather still 'very tricky' 24 Aug How reliable were these weather forecasts? The process of forecasting the weather was still "very tricky", according to MetService meteorologist Andy Best. "Obviously, models have a certain degree of resolution ... we can use a model, but it de- pends on the initial conditions, as well as how accurate the data is that is fed into that model." Which is why forecasters relied on multiple models and verified the data gathered before sharing an official forecast.

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Forecasters rely on multiple models and verify the data before sharing an official forecast. Best said they mostly relied on three international models from the US, UK and Europe, and analysed that data three to four times a day. But "no model is perfect," Best told Stuff. Each model's behaviour over the previous days - such as its accuracy and consistency - was monitored. Best said if it had a "great deal of consistency" they had a lot of confidence in its predictions. Gathering information from satellites and data around the world was easy thanks to the World Meteorological Organization, a specialized agency of the United Nations. "It's one of the most organised global networks that there is, because it's independent of politics really, everyone contributes," he said. https://www.stuff.co.nz/national/115253137/rain-hail-or-shine-forecasting-the-weather- still-very-tricky

Rain record broken, Father's Day comes with spring weather...finally 30 Aug, 2019 7:35am Auckland has broken a new record today for the most rain days in a single month - 29 days in August to be exact. MetService confirmed the miserable milestone to the Herald this morning. It also means Auckland has now had two record months in a row after there was also 28 days of rain in July - a feat of Mother Nature that broke an earlier record dating back 10 years. Niwa figures showed, up until Sunday, Auckland had received 182mm of rain for the month – that's 165 per cent of normal – while the mean daily temperature had been running at a slightly-above-average 12.1C. https://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12263304

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