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The Great Marangai of 2023

Updated: Jan 26

The term 'Marangai' means east wind, also meaning a storm, or bad weather. However, in some districts, Marangai means the north wind. It is likely that its meaning depended on the quarter from which bad weather tends to come in that district. Over the last week the upper North Island experienced an extreme weather sequence in what could only be called the Great Marangai. Sadly this weather sequence caused a loss of life, extensive property / infrastructure damage and countless landslides.

Here is the some of the important meteorological factors and timeline of events that took place.

Jan 21st – Joint Typhoon Warning Centre names Tropical cyclone 10P near New Caledonia. It only remained a cyclone for less than 1 day.

JTWC Tropical cyclone 10P warning map

Jan 24th - The Australian weather model Access G starts to project 300mm+ rainfall event for Auckland and the Coromandel for the 26th/ 27th January. No other models looked this extreme but ultimately this would be an important hint of what was to come.

Jan 25th - Ex-tropical cyclone 10P connects with a mid-latitude trough which is dragging down large amounts of moisture from the tropics through an atmospheric river. Total precipitable water values have now increased to 50mm.

A new upper trough moves in from over the Tasman reinvigorating ex-tropical cyclone 10P.

Jan 26th - Ex-tropical cyclone 10P develops into deeper subtropical low with a rainband extending ahead of a warm front into Northland.

Radar image 7:20pm 26th January

MetService issues widespread upper North Island 'Orange' heavy rain warnings.

Jan 27th - On sunrise, early signs of a significant rain event appear on water vapour images north of Northland.

King tide arrives across the Upper North Island

A significant convergence zone develops from lower Northland to southern Auckland from 2:00pm

MetService radar sequence from 2:45 to 3:07pm 27 January

Devastating and deadly flooding starts to appear in Auckland city, suburbs and roads as inundated storm water systems overload beyond capacity. 200 to 370mm was recorded in areas under the convergence zone.

1st severe thunderstorm warning was issued by MetService 4:18pm, 27th January.

MetService issues 1st RED warning for Auckland and Great Barrier Island at 9:07pm, 27th January. State of Emergency was issued by Auckland Council at 9:27pm. No emergency alert was sent by NZ Civil Defence for the day.

Jan 29th - A 2nd new upper level trough launches over the central Tasman, creating 2 new upper lows and a Fujiwhara effect.

Jan 30st - A large baroclinic leaf appeared along with a water vapour surge with equatorial origins. A consolidated upper low near Norfolk Island was in place to trigger the development of a surface low in the subtropics.

MetService issue a new Red warning for Northland, Auckland and the Coromandel

Jan 31st - Sunrise satellite imagery shows a new subtropical low with developing low-level Jetstream.

Wind gusts in the gulf clocked 64 knots 119 km/h the subtropical low deepened below 1000 hPa.

Feb 1st - A new convergence zone forms over the Gulf and moves over Auckland before sunrise. another 80 to 110mm falls on the city in only a couple of hours exacerbating and causing more flash flooding issues.

Feb 3rd - A final round of light to moderate rain fell across the upper North. Bringing to a close the most extreme rain event ever recorded in New Zealand's modern history for its most populated region.

Here are the final rainfall totals over 8 days from 27th January to 3rd February 2023 across the upper North Island recorded on private online gauges.

572 Hobsonville point

520 Albany

520 Sunnynook

514 Glenfield

503 Paremoremo

502 Greenhithe

500 Bayswater

495 Mt Eden

484 Orewa

483 Birkenhead

476 Torbay

467 Herne Bay

466 Wellsford

461 Auckland city

461 Beach Haven

458 Browns Bay

456 Mairangi Bay

453 Northcote Point

450 Campbells bay

449 Swanson

446 Puhoi

441 Beachlands

440 Chatswood

440 Warkworth

440 Kumeu

439 Castor Bay

439 Milford

439 Murrays Bay

427 Coatesville

421 Millwater

421 Silverdale

414 Epson

411 Belmont

405 Gulf harbour

404 Clevedon

403 Titirangi

400 Huapai

399 Stanmore Bay

399 Dairy Flat

398 Grey Lynn

388 Birkdale

385 Devonport

385 Matakana

378 Leigh

377 Pataua North

374 Waiuku

370 St Heliers

366 Awhitu Peninsula

365 Riverhead

364 Coromandel town

359 Great Barrier Is

358 Kaipara Flats

349 Whangamata

349 Pauanui

347 Kaiwaka

347 Whangaparaoa

346 Mangawhai

344 Algies Bay

343 Henderson

342 Ellerslie

340 Mission Bay

332 Pukekohe

327 Huntly

317 Whitianga

315 Waiheke Island (Omiha)

311 Te Mata

302 Omaha

293 Port Waikato

290 Waihi

287 Glorit

278 Kopu

275 Waiheke Island (Onetangi)

271 Whenuapai

267 Thames

265 Papakura

264 Tauranga

261 Hamilton

260 Howick

257 Matarangi

251 Wharekawa

243 Kaukapakapa

237 Langs Beach

235 Bucklands beach

233 Whangarei

228 Ngatea

225 Waipu

223 Hunua

219 Ruakaka

214 Matapouri

214 Tutukaka

210 South Head

200 Waiheke Island (Matiatia)

192 Kerikeri

185 Helensville

185 Bombay

174 Muriwai

102 Dargaville

Note: With heavy downpours, some localised large differences can occur between close gauges

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