NIWA’s Hotspot Watch | Scoop News

Recent rainfall and current soil moisture
conditions:

In the North Island, weekly
rainfall totals of 50 to 100 mm were recorded for much of
Wellington, the Manawatū-Whanganui east and north of
Palmerston North, the Waikato from Hamilton eastward
including the Coromandel, eastern Northland, Bay of Plenty,
Hawke’s Bay, and Gisborne, with a few pockets of 100 to
200 mm in the central North Island mainly about the ranges
and foothills. Elsewhere, 10 to 30 mm of rain fell across
Taranaki, western Waikato, most of Auckland, remainder of
Northland, the Manawatū-Whanganui about Foxton and
Palmerston North, with a few areas in Auckland and Northland
recording less than 10 mm of rain. The remainder of the
North Island recorded 30 to 50 mm of rain over the past
seven days. A moderate to large increase in soil moisture
occurred in Wellington, most of the Manawatū-Whanganui,
Hawke’s Bay, Gisborne, Bay of Plenty, the Waikato about
Taupo, and Northland about Whangarei. Soil moisture
increased slightly for Taranaki and the Coromandel
Peninsula. Elsewhere, soil moisture remained the same or
decreased slightly for the remainder of Northland and
Auckland. The driest soils, when compared to normal for the
time of year, are found along the Northland coast west of
Kaitaia and north to Cape Reinga, with the wettest soils,
when compared to normal for the time of year, are found in
Northland about Whangarei, Waikato about Tokoroa, Bay of
Plenty about and south of Rotorua, Gisborne, northern
Hawke’s Bay and the Central Hawke’s Bay District, the
Tararua District, and the eastern Wellington
region.

The hotspot about the Manawatū-Whanganui
coast near Foxton remains while the hotspot in Northland
about Tauroa Point to North Cape has strengthened. As of 17
February, the New Zealand Drought Index (NZDI) map shows
abnormally dry to very dry conditions in the Far North of
Northland.

In the South Island, weekly rainfall totals
of 50 to 100 mm were recorded about Christchurch and
Bank’s Peninsula, in North Canterbury about Kaikōura and
Cheviot, and in the Southern Alps of Westland, with a few
pockets of 100 to 150 mm of rain about Bank’s Peninsula.
Elsewhere, 30 to 50 mm of rain were recorded across Otago
from Dunedin south to Balclutha, in Canterbury mainly about
the high country, about Lincoln, and pockets of North
Canterbury mainly along the foothills, Fiordland, and much
of Westland south of Greymouth. The remainder of the South
Island recorded less than 30 mm of rain, with portions of
Southland, Stewart Island, inland Otago, Marlborough, and
southern Tasman recording less than 10 mm over the past
seven days. A moderate to large soil moisture increase
occurred across coastal Otago, the Canterbury low country
including Christchurch and Bank’s Peninsula, and Stewart
Island. Soil moisture remained the same or decreased
slightly across the remainder of the South Island. The
driest soils in the South Island, when compared to normal
for the time of year, are in Southland west of Invercargill
and Westland about Hokitika. The wettest soils, when
compared to normal for the time of year, are in North
Canterbury about Kaikōura and Bank’s Peninsula.

A
hotspot has formed in Southland just west of
Invercargill.

As of 17 February, the New Zealand
Drought Index (NZDI) map shows a very small area of
abnormally dry conditions in Central Otago.

As
of 17 February, the New Zealand Drought Index (NZDI) map
shows abnormally dry to very dry conditions in the Far North
of Northland and a very small area of abnormally dry
conditions in Central Otago.

The
week ahead:

In the North Island, high
pressure will be on top of or near the North Island through
the next seven days. A west-southwest wind flow will bring
occasional showers under otherwise dry weather conditions
Friday through Sunday, with little to no rain expected by
Monday (23 February). A weak front moves across the North
Island on Tuesday with a few showers, mainly for the lower
North Island. For Wednesday and Thursday (25-26 February)
sea breezes will dominate, allowing for a few inland
showers. Weekly rainfall totals of 10 to 30 mm are expected
for all of the North Island, with some locations about the
north and east of the North Island expecting less than 10 mm
of rain.

Due to the expected rainfall in the next
week, soil moisture levels will likely see moderate to large
decreases. The hotspots in the Manawatū-Whanganui and
Northland will likely strengthen over the next
week.

In the South Island, a front moves across on
Friday with rain and showers, along with a few thunderstorms
along the east of the South Island, and a cool southwest
wind flow. A short period of high pressure is expected
overnight Friday, followed by another front with more rain
on Saturday night and Sunday (21-22 February), with the
heaviest rain in Fiordland. High pressure follows late
Sunday to early Monday, with another period of possible
heavy rainfall for the west and south of the South Island on
Monday and early Tuesday. Settled weather returns for
Tuesday afternoon through early Wednesday, with another
front with rain for the west and south of the South Island
on Thursday (26 February). Weekly rainfall totals of 30 to
50 mm of rain are forecast for the west and south of
Southland and Westland from Westport south to Haast, with 50
to 100 mm of rain expected for lower Westland, the Southern
Alps, and Fiordland. For the remainder of the South Island,
expect 10 to 30 mm of rain over the next week.

Due to
the expected rainfall in the next week, soil moisture levels
will likely see a small to moderate increase across
Fiordland. Otherwise, expect soil moisture to remain the
same or decrease slightly for the remainder of the South
Island. The hotspot in Southland will likely remain the same
or weaken over the next week and a hotspot may form in Otago
over the next seven day period.

Long-term
outlook (through late-March):

• In the
drier (25th percentile) scenario, drier than normal
conditions are signalled for the entire country, with very
dry conditions for the south, central, and west of the North
Island, and large portions of the South Island.

•
The middle (50th percentile) scenario shows dry conditions
for all of the South Island, including a very dry signal for
parts of Otago and Mackenzie Country, and dry conditions for
the west and south of the North Island, with near normal
conditions elsewhere across New Zealand.

• In the
wetter (75th percentile) scenario, wetter than normal
conditions are signalled for the north and east of the North
Island, with potential for very wet conditions in Northland,
a dry signal for the inland South Island, and near normal
conditions elsewhere.

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