Weekend Forecast 25th - 26th August 2012

[JennyLeez]

Issued from the Metservice
In Brief:
Saturday
Northland, Coromandel Peninsula
Fine spells. A few showers clearing tomorrow.
Auckland to Waitomo and Taumarunui, also Bay of Plenty, the central high country, and from Gisborne to Wairarapa
Fine, apart from isolated afternoon showers inland today, and the odd shower in Bay of Plenty tomorrow morning.
Taranaki, Wanganui and Manawatu
Fine, apart from cloud with the odd showers in Taranaki.
Kapiti and Wellington
Fine today. Cloudy periods tomorrow with the odd shower.
Nelson and Marlborough
Fine today. Becoming cloudy tomorrow with showers developing, but remaining dry in eastern Marlborough.
Canterbury, Otago and Southland
Mainly fine, but brief rain at times in Southland, and rain near the Divide tomorrow.
Buller to Fiordland
Mostly cloudy with patchy drizzle today. Rain spreading north tomorrow, heavy at times, with possible evening thunderstorms in Fiordland.
Chatham Islands
Cloudy periods.

Sunday
North Island, mainly fine for much of the island. Some cloud and drizzle in the far south and Taranaki, also developing later in the day in the northeastern regions. South Island, rain in the west and far north, with some heavy falls expected. Mainly fine elsewhere.
Monday
North Island, rain spreading from the southwest, changing to a few showers later on. South Island, rain easing in the west and clearing from the far north. Remaining mainly fine in the east.
Chatham Islands
Long fine spells on Sunday, with fresh northwesterly winds. Northwesterlies strengthening on Monday, and rain setting in. Becoming fine Tuesday morning as winds change lighter westerly.

In Full:
On Saturday, a high should cover the North Island and a front is expected to be move east over the southern South Island. Between these features a strengthening northerly flow covers the South Island.
The front should lie over the northern South Island late on Sunday and cross the North Island during Monday. Another, weaker front should pass over the south of the South Island on Monday.
The northerly flow ahead of the first front should reach gale force in some locations, but it is unlikely any land-based warnings will be required. The fronts are expected to bring periods of rain to western and northern places of both Islands.
There is high confidence that a rainfall warning will be required for Fiordland and Westland south of Hokitika on Saturday. The rain is likely to continue during Sunday and Monday although there is only low confidence that a rainfall warning will be required on these days. There may also be significant spillover into the headwaters of the Otago and Canterbury lakes and rivers.
On Sunday, there is moderate confidence that a rainfall warning will be needed for the rest of Westland, Buller and northwest Nelson. There is also moderate confidence that warning amounts of rain will fall on Mount Taranaki during Sunday and Monday. On Sunday and Monday, there is low confidence that rainfall warnings will extend over the rest of Taranaki, Nelson and northwest Marlborough.
As the front moves over the North Island on Monday there is low confidence that rainfall warnings will be required for Waitomo, Waikato, Northland, the Coromandel Peninsula and Bay of Plenty.

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[OhauitiWeather]

The first of the warm spring like northwesterlies kicks in this weekend for the east coasts of both islands. Temperatures are likely to be in the high teens although there will be high cloud at times particularly in the South Island then for the North Island later on Saturday and for most of Sunday.



Other areas of the North Island are likely to get mild temperatures tomorrow also. The flip side to the warm temperatures out east means rain in the west and heavy falls are possible on the West Coast of the South Island, the rain will develop tomorrow morning in South Westland moving up the coast during the weekend. 100 to 150mm is possible south of the Glaciers on Saturday and then north of the Glaciers during Sunday.

Our next southwesterly front is due early next week on Monday for the South Island then overnight Monday into Tuesday for the North Island, this will reset the clock so to speak and we’ll have a period of cooler weather. An anticyclone is then due mid to late next week coming in behind the southwesterly airflow from the Tasman Sea.

Homepage image / 25th August midday rain map - weathermap.co.nz

By weather analyst Aaron Wilkinson, WeatherWatch.co.nz
http://www.weatherwatch.co.nz/content/mild-east-weekend

[JennyLeez]

Severe Weather Watch from the Metservice.
SIGNIFICANT RAIN POSSIBLE NEAR THE CANTERBURY AND OTAGO HEADWATERS
AND ALSO NORTHWEST NELSON THIS WEEKEND.

A front is expected to move over the South Island during today
(Saturday) and tomorrow. Ahead of the front, a moist northerly
airflow is expected to bring a period of heavy rain to the west of
the South Island today and tomorrow. Some of this rain should spill
over into the headwaters of the Otago and Canterbury lakes and rivers
from late Saturday morning until Sunday afternoon. Currently it
appears that rain accumulations east of the Main Divide should remain
just below warning criteria. Forecasters will continue to monitor the
situation.

Also for northwest Nelson, rain may become heavy Sunday evening and
continue into Monday. It is currently unclear if rainfall
accumulations will reach warning criteria, and forecasters will
monitor the situation.

Even if rainfalls in these areas don't reach warning amounts, rivers
may rise rapidly and people in their vicinity should remain cautious
and are urged to keep up to date with the latest weather forecasts in
case this watch is upgraded to a warning.

[OhauitiWeather]

Most of the North Island will remain dry tonight and tomorrow as settled weather remains in place thanks to a big high pressure ridge to the east of New Zealand.

On the South Island, it’s a very different story.

Eastern Otago could end up being pretty dry over the next 36 hours.  But the rest of the Mainland is looking pretty rainy.

Especially Westland where heavy rain is expected.  Government forecaster MetService has several heavy rain warnings in effect.

• Ranges south of Fox Glacier- Heavy rain is expected tonight and during the overnight with some rainfall rates approaching 15 to 25mm/hr.  Rainfall totals are expected to reach 120 to 140mm.  50 to 70mm is possible along the coast.
• Ranges between Fox Glacier and Otira/Arthurs Pass- Heavy rain is expected tonight through early tomorrow afternoon.  Rainfall rates may approach 15 to 20mm/hr.  Totals of 100 to 140mm are expected with 50 to 70mm near the coast.
• North of Otira/Arthurs Pass- Heavy rain is expected overnight tonight through tomorrow afternoon.  Totals of 80 to 120mm are expected.  Rainfall rates of 10 to 15mm/hr are possible with the heaviest rain occurring late tomorrow morning..

Heavy rain will continue to shift north late on Sunday and will likely affect Nelson.  Heavy rain will remain a threat for Nelson into Monday as well.  No warning is in effect at this time, but it is something that will have to be watched.

Some brief heavy rain may also affect parts of the North Island on Monday with Taranaki and Northland having the highest risk.


By WeatherWatch.co.nz Analyst Howard Joseph
http://www.weatherwatch.co.nz/content/tonight-sunday-could-be-wet-western-si