Source: Radio New Zealand
A hotspot can point to where drought may be developing (File image). RNZ / Liz Garton
Unusually dry conditions forming hotspots are affecting eastern areas of both the North and South Islands following a period of hot, dry winds.
Earth Sciences New Zealand has identified the hotspots – areas where soils are severely drier than normal – in lower coastal Wairarapa, coastal Hawke’s Bay, North Otago, South Canterbury and North Canterbury.
The hotspots in both North Otago and South Canterbury have grown over the past week, while in coastal Hawke’s Bay, the hotspot has weakened during the week, but could grow stronger in the days ahead.
Earth Sciences New Zealand metereologist Chester Lampkin said hotspots can point to where drought may be developing.
“It tells the story that ‘hey this is a very unusually dry spot’, and this is an area where we need to watch for continued dryness or the potential for drought to develop.”
The New Zealand Drought Index has shown abnormally dry conditions are being found in coastal Hawke’s Bay, Gisborne, and the Wairarapa, and coastal North Canterbury, and very dry conditions found in Southern Hawke’s Bay and the Mahia Peninsula, according to Earth Sciences Hotspot Report.
In the North Island, rainfall amounts of less than 30 millimetres fell across most of the island in the past week, apart from in the Coromandel, Bay of Plenty ranges, and foothills of Hawke’s Bay.
Parts of Canterbury, Otago and Marlborough recorded under 15 mm of rain.
Sweltering temperatures have swept through parts of the country in recent days, with Christchurch Airport exceeding 30°C, and Hastings hitting 33.0°C on Thursday.
Lampkin said the dry conditions have been caused by persistent westerlies over September, October and a few in November.
“We’re getting those down-sloping winds, those westerlies, and a westerly – not only does it contain dry air, it also heats up as the air descends or moves down the mountain.
“As it slopes downward, it gets stronger, and it gets hotter.”
Australia has also experienced a prolonged heatwave from the outback to the East Coast leading to the highest November temperatures in years, including in both Sydney and Brisbane.
Will the dry conditions continue?
Lampkin said a wetter week was expected with an easterly flow moving across the North Island, and across the top of the south island, including down to North Canterbury.
Rain and cooler temperatures were going to move in between Tuesday and Thursday.
He said it’s looking like the hotspot in North Canterbury could weaken and potentially dissipate, but in the North Island, the dryness was more entrenched.
“Overall the North Island as a whole will see wetter weather than what we’ve seen over the past week, the question is how much will get into the east of the North Island, and right now it’s very questionable.
“Unfortunately I don’t think Hawke’s Bay is going to see a lot of rain.”
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– Published by EveningReport.nz and AsiaPacificReport.nz, see: MIL OSI in partnership with Radio New Zealand
