The tradition of long range weather forecasting uses planet positions relative to earth to estimate future events. Although we believe that weather patterns follow cycles, nevertheless all predictions remain as opinions, not certainties. The following are some likelihoods for coming months, although space prohibits publishing every extreme event. For all forecasting allow a few days leeway.
After a disappointing Christmas, NZ gets a cooler summer and can look forward to no droughts, but the arrival of often stormy weather, heat waves, damage from winds, flooding from high tides, and then the onset of El Nino. But first an active pre-El Nino cyclone season impacts Australia, the Pacific and NZ.
Over the next four weeks cyclones develop and affect the far north of Western Australia. One forms around 19 December and moves from west to north Australia. Then about a week later, in time for Christmas, a system north and west of Kimberley moves south then southeast but is not expected to cross the WA coastline. Meanwhile NZ gets a wet Christmas, especially in North Island.
Australia’s seasonal monsoonal trough develops around end of December and is temporarily confined to the Timor Sea. In first week of January, Queensland’s first cyclone of the season forms south of Solomon Islands and continues southeast but may largely miss Queensland. Around 7 January another cyclone forms in western Gulf and crosses Northern Territories coast, drawing energy from a monsoonal trough positioned over Darwin.
The monthly perigee of the moon is the day that the moon is closest to earth for the month. In January, February and March the perigees will be powerful, with the moon not as close again until September 2015. Consequently other countries will also be affected by extreme weather conditions.
In the second week of January, travellers to the west of the US encounter a week of torrential storms from California to Washington State. Europe gets a deep freeze, with bone chilling winds, snow and ice, and temperatures plunging to new lows, including south of England, which as well as receiving heavy snowfalls at times, experiences about a month of unusual dryness.
In NZ for second week of January, cyclonic wind and rain affects the north and east of the North island over about 3 days, affecting Coromandel, Northland, Bay of Plenty, Gisborne, and north and east Waikato. In mid January, a wintry blast crosses the top of the South island with chances of hailstorms, and Mt Ruapehu gains a coating of snow.
In the third week of January big surf and southwesterly swells create good surf conditions at Kawhia and Raglan. About 20 January, overnight winds and rain from another cyclonic system threaten to wash out North Island campers, with stormy weather easng around 21st..In January’s last week, the monsoon trough moves towards the north of Australia. Big swells repeat on NZ’s west coast but Bay of Plenty coastal waters may be calm. Western Australia sees another cyclone develop, only to drift away without threat to the coastline.
In the first few days of February, strong rips make swimming dangerous at Raglan, and gale force winds may batter the South Island, from Canterbury to Southland. The monsoon low brings heavy rain to WA over the ensuing fortnight. Then the monsoonal trough centres itself south of the Top End, until finally dissipating in the third week in March. By the second week in February, England is still dry, despite shivering through the middle of winter with heavy snowfalls and freezing conditions. By mid February, dry and windy air brings a fire risk to some NZ regions, e.g. Waikato, but after the 15th the past fortnight of sun and blue sky may start to give way to rain.
At the end of the third week in February, a cyclone forms near Cairns, crosses the coast near Townsville and then dissipates. England is still dry, and extreme tides pose risks for NZ bach owners. High tide heights, combined with a drop in atmospheric pressure can cause waves to break well onshore, affecting sandbars and exacerbating erosion. Around 21 February, flooding may occur in Greymouth, potentially closing roads and schools, and the Coromandel coastline experiences high seas. At the end of February, a cyclone develops over northern Coral Sea and tracks south and southeast towards NZ
March begins with very warm conditions in the State of Victoria and this affects our North Island farms, pushing up the risk of facial eczema. Heavy monsoonal rains over Darwin over the next two weeks cause flooding. A cyclone forms north of Townsville, tracks southwest and crosses southeast of Townsville bringing floods to Central coast. Gales in the second week of March cross the southern half of Britain and heavy rain brings flooding. From the middle to the end of March, cyclones dominate Queensland’s weather, affecting the eastern coast and PNG.. The monsoonal trough becomes confined to being over Top End over the following three weeks, and heavy rain falls in Central North Island.
By 18 March the monsoonal activity ends for WA., drifting finally away to the north of Australia by the end of March which is when cyclones will stop forming. In the fourth week of March the final cyclonic system, having passed through Fiji, brings heavy rainfalls and four days of windy weather to the Waikato and strong southeast winds to the eastern coast of Coromandel Peninsular.
El Nino is the weather phenomenon cycle lasting four and a half years, featuring high pressure over Darwin and Tahiti. It creates west and south westerly airstreams over this region, coming off the cooler seas of the south Tasman which keeps conditions cool over NZ. There are less incursions of warm subtropical air and we receive unseasonably cooler weather, which is what NZ’s coming early-to-midsummer should deliver. At the moment the next El Nino is still in the brewing stage, and may be declared around next March/April.
Ken Ring of www.predictweather.com is the author of Weather Almanac for NZ for 2015.