Soggy start to summer likely after November deluge
Wednesday, 21 November 2018
With more rain and gloom forecast to last until the end of the month and beyond, you may be wondering - whatever happened to predictions of a warm, dry November?
Dunedin is on the cusp of setting a November rainfall record after torrential rain in recent days and Christchurch could also have enough rain to end up with one of its top five wettest years.
Forecasters say more Tasman Sea depressions over the next 10 days or so will keep the rain coming in many parts of the country and give New Zealanders a very soggy start to summer.
So how does that marry up with earlier predictions from the National Institute of Water and Atmospheric Research (Niwa)?
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In its three-monthly seasonal outlook at the start of the month, Niwa said rainfall was most likely to be near average (40 per cent chance) or below average (35 per cent) along the South Island's east coast through to the end of January. Temperatures were predicted to be equally likely to be above average or average (both a 40 per cent chance).
Niwa meteorologist Ben Noll told Stuff then the country could expect warmer-than-average temperatures in the first 10 days of November. That might only be the start, with 'several rounds' of high temperatures 'as we go through the first three weeks of November'.
Asked about those predictions, Niwa's principal scientist - forecasting, Chris Brandolino, defended the seasonal outlook, saying it was for the three-month period and not just November.
'We didn't predict a dry November. We did predict hot weather, a couple of episodes, and we had 29.9 degrees Celsius in Christchurch and 31.2C in Kaikoura and Cheviot. We have had multiple episodes with temperatures falling just short and exceeding 30C.
'Predicting hot and dry [for November]? I'm not sure if I buy into that, to be honest.'
He had no control over media headlines, he said.
'The rainfall - we have it as normal or below normal. This rain that has impacted the south of the South Island, that is something that I personally, I wouldn't have expected. That probably wouldn't have been on the cards.
'Some things happen - that is just one month out of three. You can run a business and have a great week, but it doesn't mean that the quarter is going to be the same,' Brandolino said.
MetService forecaster Georgina Griffiths said November would end on a 'very wet note' for people in the east of the South Island.
'The highs of the last two and a-half months are goneburger, done and dusted.
'I don't see a particularly settled December in store nationally either. That doesn't mean we won't see some settled windows next month though. It won't be as cold as it has been.'
A MetService measure of Tasman Sea storminess showed the rain-bearing lows could dominate the weather into the first few days of December.
MetService had not predicted a hot November but instead had picked 'bouncing temperatures', she said.
WeatherWatch head analyst Philip Duncan said it was difficult enough to predict 10 days ahead, let alone issue a three-month forecast.
'Unless we have a very strong pattern, like a clear and strong El Nino or La Nina, New Zealand tends to fit into that 'chaotic' category where single highs and lows can dwarf New Zealand and dominate our weather, completely altering monthly or seasonal forecasts.'
Blue Skies forecaster Tony Trewinnard said it could take until mid-December for the weather to settle down.
'It's going to be very unsettled, it's going to be wet, though it's not going to be so unusually cold, through to the end of this month and the first week of December.'
The usual weather pattern for late spring had completely broken down in the New Zealand region, with low pressures dominating and few anticyclones to be seen.
'It's all wrong.'