Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 1
ISSN 0111 - 1736
Meteorological Society Of New Zealand (Inc.)
NEWSLETTER 153 Winter 2018
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 2 Meteorological Society Of New Zealand (Inc.) NEWSLETTER 153 Winter 2018 PO Box 6523, Marion Square, Wellington 6141, New Zealand Please forward contributions to Bob McDavitt, [email protected]
CONTENTS Page Foreword from our President 3 Conference 2018 4 Student Report POLAR 2018 5 Around the Regions in Autumn 6 Autumn: NIWA review 7 Notable events 8 - 14 Christchurch, Ben Tichborne 15 Pick of the clips 16 - 52
Your Committee 2018 President Sylvia Nichol Immediate Past President Daniel Kingston Secretary Katrina Richards Treasurer Gregor Macara Circulation Manager Lisa Murray Auckland VP Petra Pearce Hamilton VP Tim Gunn Wellington VP James Renwick Christchurch VP Jiawei Zhang Dunedin VP Daniel Kingston Journal Editor Nava Fedaeff with Jim Renwick Newsletter Editor Bob McDavitt Website Liaison Stefanie Kremser General Committee Mike Revell, Michael Martens Hydrological Society liason Charles Pearson Co - opted by committee Ciaran Doolin
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 Newsletter153 Winter 2018 Page 3 Notes from the President ’ s desk
Dear Members
It gives me great pleasure to let you know that our new website has been up and run- ning for a few weeks now.
One of the big changes is that the back - end of the new website now holds the mem- bership database for members who have an email address, and so from now on the website should automa cally send email reminders to tell members that their annual subscrip on is due.
Members who haven ’ t supplied us with an email address will con nue to receive an invoice for their annual subscrip on through the post. This process should drama cal- ly reduce the workload for our Treasurer and Circula on Manager in tracking subscrip- on payments. Many thanks are due to our Website Liaison, Stefanie Kremser, for all the work that has gone into this project.
I have been very encouraged by the recent news that the chief execu ves of 60 com- panies have formed the Climate Leaders Coali on and commi ed their companies to help New Zealand transi on to a low carbon emissions economy. This, along with the recent public consulta on process on the Zero Carbon Bill, shows that we are moving in the right direc on on this important issue.
Sylvia Nichol, President NZ Met Society July 2018
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 4
2018 Conference is in Christchurch from 4 to 7 December with NZ Hydro Soc See h p://nzhsnzms2018.co.nz/
Who ’ s on the Climate Leaders Coali on? See h ps://www.climateleaderscoali on.org.nz/
Student ’ s Grant Conference report
POLAR2018 – a joint conference of the SCAR (Scien fic Commi ee on Antarc c Research and the IASC (Interna onal Arc c Science Commi ee) had the appropriate tagline of “ where the poles come together ”. The mee ng was held in Davos, Switzerland from the 19 - 23 June 2018. Chris Cameron a ended with the support of a Student Travel Grant from the Meteorological Society of New Zealand, and reports back here on his experi- ence.
Though I had heard plenty about Davos, as both a hub for snow and ice research and as a winter ski resort, I had not begun to imagine how stunning the scenery would be. An idyllic se ng for the conference to be held.
My poster presenta on was on day two, and was one of many hundreds of posters on display – with similarly large numbers of viewers. A er several good discussions, I spoke at some length with the two poster judges about my work. My poster covered the latest findings on my PhD research into the characteris cs of the Antarc c circumpolar strato- spheric vortex - comparing how well it is represented as a mixing barrier in reanalysis compared with the UK MetOffice Unified Model (UM) and how representa on of the vortex in the latest dynamical core of the UM differs from the previous core.
Apart from other presenta ons on atmospheric science, one of the great benefits of PO- LAR2018 was the ability to a end talks on a wide range of polar related topics. These were fascina ng in terms of the range of ac vity taking place. Sessions I a ended includ- ed: Introducing the new ‘ Iridium Certus ’ satellites for global telecommunica ons The next phase of work for the BBC Frozen Planet documentary series Polar related art, including film and visual art Polar change and the future of society
I am very grateful for support from the Meteorological Society for assis ng me to a end POLAR2018. Thanks, MetSoc!
Chris Cameron
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 6
Par cipants a end a plenary session during POLAR2018
AROUND the REGIONS IN AUTUMN
Just one seminar was distributed to regional Met Soc members during autumn, but it was a good one: Wahine Day at Wellington Museum In commemora on of the 50 th Anniversary of the Wahine Disaster, Wellington Museum hosted a num- ber of special events that will happen during the day – in rememberance of the people who lost their lives, as well as the survivors and first responders who were there fi y years ago. A special Wahine exhibi on was displayed in the Museum as well as talks, and there was acknowledg- ment of th e Wahine with bell ringing every half - hour. Including, at 6pm Erick Brenstrum, Expert Meteorologist from the METSERVICE talked about the weather forecast for the 10th April 1968.
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AUTUMN A warm start to autumn, then cooler and unse led at mes. Temperature Nearly all of the North Island observed above average (0.51 to 1.20°C of average) temperatures during autumn, along with isolated pockets of near average ( - 0.50 to 0.50°C of average) and well above aver- age (>1.20°C of average) temperatures. In the South Island, most loca ons recorded near average ( - 0.50 to 0.50°C of average) temperatures during autumn, with a handful of sta ons observing above average (0.51 to 1.20°C of average) temperatures. Rainfall Autumn rainfall in the North Island was generally near normal (80 - 119% of normal) or above normal (120 - 149% of normal), with a handful of loca ons also recording well above normal (>149% of normal) rainfall. In the South Island, above normal (120 - 149% of normal) or well above normal (>149% of nor- mal) rainfall was observed in most loca ons, with a few spots also recording near normal (80 - 119% of normal) rainfall. Soil moisture As of 1 June, soil moisture was near normal in most of the North Island, along with the western and southern South Island. However, soils were we er or even much we er than normal in small por ons of the lower North Island and nearly all of the eastern South Island. Overview Autumn 2018 began on a warm note, as March was characterised by significantly higher pressure than normal to the east of New Zealand. This pressure pa ern, in concert with the decaying La Niña in the tropical Pacific, caused more northeasterly winds than usual over the country. Warm, humid air mass- es, combined with the remnants of the marine heatwave in the Tasman Sea, influenced higher than usual temperatures over New Zealand as well as some heavy rainfall events. However, the pressure pa ern for April resulted in more southwesterly winds than normal for much of the country. Several low pressure systems and cold fronts passed over New Zealand, bringing adverse weather to many loca ons. Storms occurring on the 10th - 11th and 28th - 29th days of the month were par cularly damaging with the former bringing destruc ve winds to Auckland, while the la er brought heavy rain to parts of the country, resul ng in flooding and the declara on of a state of emergency in Rotorua. In May, mean sea level air pressures were much lower than normal over and to the south of New Zea- land. The first half of the month was rela vely warm and dry throughout the country. However, during the second half of May, a blocking an cyclone became established over the southeast of Australia, which delivered a prolonged period of disturbed westerly and southwesterly winds over the country. A ridge of high pressure covered the lower South Island during the final days of May, bringing heavy frosts and record cold temperatures to parts of Central Otago, Southland and the Mackenzie Basin. Further highlights The highest temperature was 31.8°C, observed at Kawerau on 5 March. The lowest temperature was - 8.8°C, observed at Mt Cook Airport on 31 May. The highest 1 - day rainfall was 205 mm, recorded at Secretary Island on 19 March. The highest wind gust was 187 km/hr, observed at Aki o on 21 May. Of the six main centres in autumn 2018, Auckland was the warmest, Dunedin was the coolest and least sunny, Auckland and Wellington were the equal - we est, Christchurch was the driest, and Tauranga was the sunniest. Contact For further informa on, please contact: Mr Chris Brandolino, Principal Scien st – Forecas ng, NIWA Na onal Climate Centre Tel. 09 375 6335, Mobile 027 866 0014 Mr Seth Carrier, Meteorologist/Forecaster, NIWA Na onal Climate Centre Tel. 09 375 4508
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 8
NOTABLE WEATHER IN NZ – AUTUMN 2018
This autumn was very varied with regards to weather. There were several stormy spells, with a few of them causing severe damage, due to high winds and heavy rain. Temperatures were very variable, with some warm periods, but also some early wintry outbreaks.
MARCH 1 st – Unusually warm in northwest of South Island in a northeasterly flow, eg 27C maximum at Arapito. (near Karamea) 3rd – Warm day on South Island West Coast, eg 28C maximum in Westport. 4 th – Heavy fog blankets Otago Harbour, disrup ng opera ons at Port Chalmers. 5 th/ 6 th – Very warm in many parts of North Island, especially in the north. New March records of 28C broken in Whi anga (6 th ) and Rotorua. (5 th ) Other highs include 29C in Hamilton and Te Kui (both on 5 th ), 28C in Paeroa (5 th ), 27C in Mangere, Auckland (6 th ), and 26C at Motu. (6 th ) Overnight minimums are also very high in many areas, eg 19C at Wellington Airport on 6 th . Thick fog disrupts opera ons at Auck- land Airport in morning. 7 th /8 th – Heavy rain in parts of North Island, with locally severe flooding in parts of Hawkes Bay. (see details below) 12 th – Ex - tropical cyclone brings heavy rain to eastern Northland, Coromandel Peninsula, and East Cape. (as much as 100mm recorded in la er two areas) 13 th – A few a ernoon thunderstorms reported in North Canterbury. 19 th – Heavy rain in Fiordland. Secretary Island records 205mm, its highest recorded March daily total. Northwesterly gales in exposed parts of lower South Island, eg 109 km/hr gust recorded at Lauder. 21 st – Heavy downpour causes flooding in New Plymouth. 22 nd – Unusually cold in lower South Island, under cloud, rain, and a southerly flow. Snow down to about 700m in Central Otago, with 30cm recorded at Cardrona Ski Resort. Record March low maxi- mums recorded in Wanaka (6C) and Oamaru (9C), while highs in high single figures recorded at many other Otago and Southland sta ons. Further north, heavy rain affects many central areas, with flooding reported about Nelson and the Kapi Coast. (some homes flooded in la er area) 130mm recorded in Stra ord, and 105mm in Nelson. 23 rd – Heavy downpour in the far north causes a washout on SH1 between Kaitaia and Cape Reinga. 24 th – Thunderstorms with a few heavy downpours reported in West Auckland. 27 th – Northwesterly gales in some inland eastern parts of South Island. Campervan blown over by the winds near Mt Cook Village, while scenic flights are cancelled in that area. 31 st – Thunderstorm reported near Oamaru, during a southerly change in the a ernoon.
APRIL 2 nd – Unusually warm 23C maximum in Lumsden, in a northwesterly flow. 3 rd – Unusually warm 25C maximum in Takaka. 4 th – Warm day in east of South Island, eg 26C maximum in Oamaru. 5 th - Warm in north of North Island (eg 24C maximum in Rotorua and 27C in Whi anga), under sun- shine and light winds. 6 th – Warm northwesterly flow results in summery maximums in east of South Island, eg 28C in Akaroa. 9 th - 13 th – Stormy period, including damaging winds in Auckland and an unseasonably early wintry blast. (see details below) 14 th – Unseasonably heavy frosts in Central Otago and Southland, eg - 4C minimums in Clyde and Lumsden. 15 th – Thunderstorms on South Island West Coast. 19 th /20th – Westerly gales in some exposed eastern areas, eg 141 km/hr gust at Castlepoint (19 th ), and 82 km/hr in Dannevirke. (20 th ) 20 th /20 th – Cold and showery in far south in a strong west to southwest flow, with snow above about
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 9
700m on high country. Late a ernoon/evening southerly change brings thunder and hail in parts of Canterbury, including Christchurch. 21 st – Snow on lower South Island high country (including a dus ng at Mt Cook Village) in morning, in a cold but easing southwesterly flow. 27 th - 30 th – Heavy rain in many areas, with severe flooding around Rotorua. (see details below)
MAY 1 st – Unseasonably warm in northern areas, eg 23C maximums in Hamilton (new May record) and Tau- ranga, 22C in Te Puke and Whakatane, 21C in Taupo, and 20C in Rotorua. 8 th – Northwesterly gales in the far south, eg 89 km/hr gust recorded at Manapouri (new May record), 153 km/hr at Puysegur Point, 107 km/hr in Gore, and 85 km/hr in Queenstown. 9 th – Unusually warm in north of South Island, eg 23C maximum in Motueka, and 19C on Brothers Is- land. 11 th – Some heavy rain in northern and central North Island. 152mm recorded at North Egmont. 12 th – Freezing fog in parts of Otago and Southland. Only 5C maximum in Alexandra. 13 th – Only 4C maximum in Alexandra, as freezing fog and cloud con nues. By contrast, warm north to northwest flow pushes maximums up to 23C at Whenuapai, Auckland, and 21C in Whangaparoa. 14 th – Warm, humid north to northwest flow con nues in northern areas, with a 23C maximum at Western Springs, Auckland, and 22C in Hamilton. Heavy rain in eastern Bay of Plenty, eg 117mm in Whakatane. Thunderstorms in Taranaki, with lightning strikes causing power - cuts to more than 2000 proper es. 15 th – Strong wind gusts cause some damage in and around Tauranga. 16 th – Warm in north and east of North Island, eg 24C maximum in Wairoa, and 23C in Whi anga. 17 th – Disturbance in southwesterly flow brings period of thunderstorms to Auckland, with reports of large hail. 20 th – Northwesterly gales in some eastern areas of South Island. Winds cause disrup on to flights at Dunedin Airport and fan a fire near Taieri Mouth. Gusts reach 89 km/hr in Oamaru and 82 km/hr at Tara Hills. Thunderstorms about and west of the Southern Alps; lightning striking two aircra heading to Queenstown. (which had to be diverted) 21 st – Northwesterly gales cause some damage in Wairarapa. 187 km/hr gust recorded at Aki o; 143 km/hr at Castlepoint. Thunderstorms affect Wellington/Kapi and Taranaki during the early hours, with some 700 lightning strikes recorded. Colder air affects southern South Island, with snow on the high country. SH 94 to Milford Sound closed by snowfall. 22 nd – Trough and fronts cross NZ, with strong northwesterly flow over NZ being replaced by strong, colder west to southwesterlies in the south. Heavy rain causes surface flooding in parts of Central Ota- go and inland Southland. About 9500 lightning strikes are recorded across New Zealand as thunder- storms affect many areas. Thunderstorm downpour with heavy hail also causes surface flooding in Wel- lington. 23 rd – Cold, unstable southwesterly flow spreads over NZ, with hail in several areas, especially the west and south, also Canterbury. (including parts of Christchurch in a ernoon) Snow to low levels in inland Southland and parts of Otago. 24 th – Cold, disturbed southwesterly flow over NZ, with more thunder and hail in western and southern areas. Snow showers on high country areas of both island. SH94 to Milford Sound, SH6 Haast Pass, SH73 at Arthurs Pass, and SH1 Desert Road are closed by snow. 25 th – Unse led weather con nues over NZ, as complex low forms, one centre to west of central NZ with west to northwest flow over North Island, while other centre lies to southeast of South Island with a cold south to southwest flow developing. Thunderstorms affect many parts of North Island, with about 575 lightning strikes reported in Taranaki, 400 in Waikato and about 100 in the Bay of Plenty. A few thunderstorms in early morning also over Banks Peninsula, and sca ered hail in parts of Canter- bury later. Snow on southern high country. 27 th /28th – Strong, cold south to southwest change sweeping over NZ on 27 th , with cold southerly flow
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 10 persis ng over country on 28 th . Snow showers on high country of both islands, with falls as low as 200m reported in North Canterbury. Desert Road closed overnight. Hail in some southern and eastern areas, eg Wellington during morning of 28 th . Day me maximums were well below normal, especially on the 28 th , eg 2C in Waiouru, 6C at Waipara, 4C in Stra ord (new May record), 9C on Brothers Island, 11C at Whangaparoa. (another new May record, and 12C in Dargaville and Whenuapai. 29 th - 31 st – High gradually moves onto NZ during this period, though with a weakening cold southerly s ll bringing showers to east of North Island. Elsewhere, frosts are widespread, and o en severe in in- land areas. Overnight minimums include - 8C at Mt Cook Airport (31 st ), - 7C in Alexandra (30 th ), - 2C in Dunedin (31 st ), and 0C in Whangarei and Warkworth. (30 th ) Freezing fogs in Central Otago and the Mac- kenzie Country also supressed maximum temperatures. New record low maximums for May include - 2C at Lauder (31 st ), - 1C at Tara Hills, and 0C at Manapouri (30 th ) and Alexandra. (31 st )
MAJOR EVENTS 7 th - 9th March – Heavy rain in parts of North Island, with locally severe flooding in parts of Hawkes Bay A slow - moving frontal system to the south of a low resulted in very heavy rain in parts of the central and lower North Island, with severe flooding inland from Napier. A low which had developed in the North Tasman the day before, moved onto the west of the North Is- land late on the 7 th . Fronts on its eastern edge brought warm, moist air from the north onto the North Island. Meanwhile, cooler air from a southerly change over the South Island reached the lower North Island that night. The clash between the two systems resulted in rain becoming heavy in some central and lower North Island areas. Lower Retaruke (southern King Country) recorded 160mm, it ’ s we est March day on record, while other high totals included 110mm at Castlepoint, 85mm in Taumaranui, 67mm in Hawera, and 63mm in Turangi. The heavy rain persisted in these areas through the 8 th , as the low moved to the north of the Bay of Plenty, but frontal systems remained slow - moving to its south. Par cularly intense falls were recorded in the Esk Valley inland from Napier. Some 200 people had to be evacuated from the area, with more than 80 proper es affected by the flooding. Elsewhere, SH43 was closed between Whangamomona and Taumaranui due to slips, and more than 100 tourists were trapped by slips and flooding on the upper Whanganui River for a me. High rainfall totals for the day included 92mm in Dannevirke and 57mm at Mahia. In the flood ravaged Esk Valley, there were reports of more than 300mm recorded in the two - day period. Overnight 8 th /9 th , the weather system weakened, with rain easing. A cool south to southeast flow spread over the North Island on the 9 th , with the weather s ll damp in southern and eastern areas, but no more heavy falls.
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Mean sea - level analyses for 1pm NZDT 7th March to 1am NZDT 10th March in 12 - hour steps are shown here., courtesy of MetService
9 th - 13 th April – Stormy period, including damaging winds in Auckland and an unseasonably early wintry blast Low pressure systems crossed NZ during this period with stormy weather, including devasta ng winds in Auckland, and a very early wintry southerly with early snow to low levels on the high country of both islands. On the 9 th , a low deepened in the mid - Tasman Sea, with very cold southerlies to the south of it. Mild northerlies affected the North Island, but colder air gradually spread onto the South Island with snow levels lowering from the south later in the day. A strong, very cold southerly flow covered the South Island on the 10 th , spreading onto the lower North Island by later in the day. Snow fell to unusually low levels (about 200m) for so early in the year in the south and east of the island, and then reached the Central North Island high country by the end of the day. Record low April maximums included 1C in Hanmer, 4C in Culverden, 5C in Kaikoura, 7C in Rangio- ra, and 9C in Palmerstorn North. Gales on the West Coast felled trees and knocked over some vehicles, with SH6 closed for a me between Ross and Franz Josef and SH67 between Westport and Karamea al- so blocked. (this me by roofing iron blown off a building) Gusts reached 122k/hr at Westport Airport. As the low approached the North Island on the 10th, very strong and squally northwesterly winds lashed northern and western areas. Taranaki was hard hit by gales, with trees and proper es damaged – some 12,000 proper es losing power. More than 13,000 lightning strikes were recorded in the area. Two tornadoes were reported – one at Rahotu, Taranaki, and the other in Na onal Park township, both causing significant damage. About Cook Strait and Wellington, southerly gales and heavy rain devel- oped, with some surface flooding about Central Wellington and Lower Hu . High gusts recorded includ- ed 139 km/hr at Brothers Island (new April record) and 143 km/hr on Mt Kaukau. All Inter Islander fer- ries were cancelled due to high seas in Cook Strait. (coincidentally, it was the 50 th anniversary of the Wahine disaster) However, the most significant wind damage occurred in the evening in Auckland. Overnight 10 th /11 th ,
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 12 gusts reached hurricane force, with widespread damage to trees, power - lines and buildings. Power was out to many areas, with 129 lines reported felled and about 120,000 proper es losing power. Many homes and vehicles were severely damaged by fallen trees and numerous windows were smashed. Public transport (both on land and on the water) was badly disrupted and the airport was forced to close with the cancella on of all flights. Not surprisingly, new record high gusts for April were recorded in the Auckland area, including 113 km/hr at Whenuapai, 95 km/hr at Western Springs, and 82 km/hr in Pukekohe. Unofficially, even higher gusts were recorded, including 146 km/hr at the Sky Tower. During the 11 th , the front and an associated low moved to the east of the North Island, with an unsea- sonably cold southerly flow over the country. Snow on the North Island high country briefly closed the Desert Road and fell as low as 500m. There were even excep onally early coa ngs of snow further north on Mt Tarawera and Pirongia. Day me maximums not surprisingly were unseasonably low, with new April records broken in Waiouru (3C), Rotorua (9C), Whakatane (10C), and Warkworth. (14C) Thun- der and hail affected Wellington, with a lightning strike causing disrup on at the airport and heavy hail making some roads hazardous. Overnight 11 th /12, there was a clearance with frosts in many areas. Lows included 0C in Kaikoura, a new record for April. The clearance was short - lived however, with another trough moving in from the west on the 12th, with rain in western and southern areas, and more snow for the South Island high country. Strong south- westerlies followed the trough in southern areas, with gales in Central Otago, resul ng in some trees felled and power cuts in Alexandra and Clyde.
Condi ons eased during the 13 th , as a weak ridge moved onto much of NZ.
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Mean sea - level analyses for midday NZST 9 th April to midday NZDT 13 th April in 12 - hour steps are Mean sea - level analyses for midday NZST 9 th April to midday NZDT 13 th April in 12 - hour steps are shown here, courtesy of MetService
27 th - 30 th April – Heavy rain in many areas, with severe flooding around Rotorua Another storm affected many areas during this period, with heavy rain, gales, and snow on the south- ern high country. The most significant weather recorded was a very heavy rainfall in the Rotorua Dis- trict with severe flooding resul ng. A low deepened in the North Tasman during the 27 th , while a trough moved onto the South Island; cold- er southerlies developing in the south later. During the 28 th , the Tasman low moved only slowly eastward to lie west of Northland late in the day and remained there for most of the 29th. Fronts in a strong, humid northerly flow on its eastern side brought thunderstorms and heavy rain to the north of the North Island. Flooding affected many areas, with several roads closed on the Coromandel Peninsula and near Tauranga. Piha also experienced flooding when a stream burst its banks. This area was also lashed by gales, with yet more damage in Auckland. (trees felled and power cut) Gusts reached 128 km/hr in Mangere, Auckland and 102 km/hr
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 14 in Paeroa – both new April records. However, the Rotorua District was most severely affected. 167mm of rain fell on the 28 th /29 th , with 51mm falling in one hour from 10AM 29 th . (the city ’ s highest one - hour total on record) Surface flooding was widespread, with several vehicles submerged. A state of emergency was declared in Ngontotaha, where the Ngongotaha Stream burst its banks and flooded many proper es. Some 200 people were trapped by the floodwaters at the Rotorua Agrodome. To the south of Rotorua (at Earthquake Flat), the rain caused a large fissure to open in an old fault - line. In the central and lower South Island, cold undercu ng air also brought heavy rain in some areas on the 28 th /29th. SH1 south of Timaru was affected by surface flooding, as was the Dunedin area where several roads were closed. Record high April rainfall totals were recorded on the 28 th at Timaru Airport (85mm) and 96mm at Orari Estate. Other high totals included 63mm in Dunedin (29 th ), 61mm in Ash- burton (28 th ), and 58mm in Waimate. (28 th ) Snow fell on the inland high country, as low as 600m in the Mackenzie Country. Three trampers were trapped by deep snow at about 1600m in Aoraki/Mt Cook Na onal Park and had to be rescued by rescue helicopter. The low weakened overnight on the 29 th /30 th but remained slow - moving over the North Island during the 30 th, while a weak ridge moved onto the South Island. Rain became lighter in most areas and cleared from the lower South Island. However, some more thunderstorms affected the western Bay of Plenty in the early morning, with a tree split in half in Te Puke and falling on a house.
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Mean sea - level analyses for midday NZST 27 th April to midday NZST 30 th April in 12 - hour steps are shown here., courtesy of MetService
MONTHLY WEATHER NOTES FOR CHRISTCHURCH – AUTUMN 2018 MARCH While a changeable month, with several troughs crossing over, it was s ll drier than normal with above normal temperatures. The first four days were warm, but the warmest day was on the 31 st , in a north- westerly flow. By contrast, the 22 nd was an unusually cold day, as lows to the east and north brought a damp southwesterly flow to the city. Much of the month ’ s rain fell on this day. A thunderstorm affect- ed areas just to the north on the 13 th .
APRIL A month of great variety, with several se led periods, but it also saw a few stormy spells. Tempera- tures varied, with one very cold spell. This, on the 10 th /11 th , brought rain and hail to the city, with snow on Mt Herbert and the upper plains. A er it cleared, there was a frost on the morning of the 12 th . The 28 th /29 th was also cold and wet, while a southerly change on the evening of the 21 st brought brief thun- der and hail. By contrast, the 3 rd (during the morning, before a southerly change) and 6 thth were sum- mery with maximums in the high 20s.
MAY Several airflows from the westerly quarter saw dry, mild weather predomina ng for large parts of the month, but cold southerlies brought more wintry condi ons during the last week. The first 10 day was mostly fine, mild weather with high pressure, followed by westerly flows. The 11 th - 16 th brought low pressure to the north and west with onshore flows bringing some (mostly light) rain and drizzle. Then there was a return to westerly flows with dry, mild condi ons un l the 23 rd . However, the flow tended colder southwesterly from the 23 rd - 26 th , with some showery periods, and hail on the a ernoon of the 23 rd . Strong, cold southerlies brought showers and some more hail on the 27 th /28 th , plus snow on the higher Banks Peninsula hills and the foothills. The last three days of the month remained cold under a light southerly flow, but were mostly dry.
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 16
CHOSEN CLIPS IN THE MEDIA FOR AUTUMN
Chosen Media clips for AUTUMN February in Nelson the we est on record 2 March 2018 Nelson Mail Nelson has had the we est February on record, and it looks like the satura on isn't over yet. Figures taken from Nelson Airport showed 234mm of rainfall for the month. MetService meteorologist Tom Adams said it was 3.7 mes the February average.
"Just for comparison, Blen- heim Airport saw 199mm which is four mes the Feb- ruary normal."
h ps://www.stuff.co.nz/nelson - mail/ news/101916312/february - in - nelson - the - we est - on - record
MetService's faulty Whangarei gauge fails to record rainfall for days 7 Mar, 2018
Compe tors in damp Beach 2 Basin fun run, Sunday. Photo / Tania Whyte Northern Advocate
The Northern Advocate contacted the MetService yesterday a er no cing on its website that no rain had been recorded for Whangarei on Sunday. This was despite atrocious weather and heavy rain mark- ing the Beach 2 Basin event that started at the Onerahi Foreshore on Sunday morning. MetService meteorologist Hannah Moes said it looked like a faulty sensor had not triggered the usual alerts that the system was down, but a technician was being sent to check the equipment. The weather sta on, which is inside a louvred box at the airport, s ll recorded temperatures and wind speeds over the past week and those figures are accurate. Rain falls into the rain gauge in the weather sta on and the amount in the gauge is measured by sensors, which may be faulty.
Meteorological Society of New Zealand Newsletter153 Winter 2018 Page 17
''If it was technical, it wasn't recorded and therefore can't be counted [in the monthly and yearly rain- fall totals] and that will affect the rainfall sta s cs. If it was programming then we should be able to retrieve the data. '' (Abridged) h ps://www.nzherald.co.nz/the - country/news/ar cle.cfm?c_id=16&objec