A warmer than normal November -January is on the cards with NIWA predicting there'll be plenty of sunshine for beachgoers.
A warmer than normal November -January is on the cards with NIWA predicting there'll be plenty of sunshine for beachgoers.
Northland is in for a warmer than normal November-January, but with a La Niña weather pattern there's also the risk of cyclones hitting the region.
Niwa has released its climate summary for November to January and is predicting that Northland has a 65 per cent chance of having above-average temperatures, with rainfall likely to be near or below average.
However, Niwa meteorologist/forecaster Ben Noll said as a result of La Niña the risk of Pacific tropical cyclones hitting the region is elevated.
''Those with marine interests north of the country should closely monitor the situation. On average, one tropical cyclone passes near the country each year, bringing heavy rain, strong winds, and rough seas,'' he said.
In Northland temperatures are very likely to be above average (65 per cent chance). Rainfall totals are most likely to be near normal (45 per cent chance).
''The potential for sub-tropical low pressure systems is elevated, particularly in the northern part of the region such as Northland. These systems can bring heavy rainfall and cause flooding,'' Noll said.
Soil moisture and river flows are about equally likely to be near normal (45 per cent chance) or below normal (40-45 per cent chance).
He said there is a progression toward La Niña conditions - and Niwa has moved to La Niña Alert.
''There is an 80 per cent chance for the development of a formal La Niña event between November-January, based on international guidance.''
New Zealand's coastal water temperatures were warmer than average during October, ranging from 0.5C to 1C above average. Anomalies decreased slightly compared with September, but are expected to increase in the next month or two. This is expected to have an upward influence on air temperatures around the start of summer.
Ex-tropical cyclone Wilma battered the Far North on January 29, 2011. Niwa is predicting cyclones are likely to hit the region again over the next three months.
■ What is a La Niña?
El Niño and La Niña are opposite phases of a naturally occurring global climate cycle known as the El Niño Southern Oscillation, or ENSO for short. ENSO influences rainfall, temperature, and wind patterns around the world, including New Zealand. El Niño and La Niña episodes occur on average every few years and last up to around a year or two.
During an El Niño event, ocean water from off the coast of South America (near Ecuador and Peru) to the central tropical Pacific warm above average. The warming takes place as trade winds (the permanent east-to-west prevailing winds that flow around the equator) weaken or even reverse, blowing warm water from the western Pacific toward the east. As a result, sea temperatures in the far western Pacific can cool below average. The unusually warm water in the eastern Pacific then influences the Walker Circulation, acting as a focal point for cloud, rainfall, and thunderstorms.
During El Niño, New Zealand tends to experience stronger or more frequent winds from the west in summer, which can encourage dryness in eastern areas and more rain in the west. In winter, the winds tend to blow more from the south, causing colder temperatures across the country. In spring and autumn, southwesterly winds are more common.
