Fickle winter weather this year
THURSDAY MAY 07, 2015
Winter this year will be late, which means we can all enjoy mild temperatures for a while yet, despite the usual intermittent colder winter spells from southerly flows. There may even be spring bursts of blossoms and grass growth resulting from the mild early winter. The southern hydrolakes will be seriously low before August, prompting media speculation of a looming power crisis.
The Indian summer conditions are expected to drift away in the last week of May, and an overdue autumn then sets in, dry for many e.g. Waikato. . This year the wintry blasts come later than usual, but they do arrive. The weather will blow hot and cold leaving many to wonder what the season is about. But at the late end to the North Island ski season, ski operators will not be too displeased with the year if they decide to extend the season by a month.
The El Nino system should keep many eastern regions dry for the winter, particularly Canterbury and Otago from July onwards, despite eventual snow in the high country and odd snowfalls in coastal towns. Marlborough is expected to begin a prolonged drought around mid June, which may only be properly relieved by heavy rains in the last week in March of 2016.
The first polar blast of winter for Canterbury that blocks roads, closes schools and traps motorists is not expected until the last few days of June, just before the combination of southern declination and full moon at the start of July. Snow may blanket inland Canterbury, but only light falls are expected for Otago and Southland.
This will coincide with the aphelion, the traditional situation around the first week of July, when the sun is always the furthest distance from earth for the year. It is why one of the coldest days of this year is likely to be 7 July, and may even break some 20-year records. Grass level temperatures may plunge to between minus five and ten in inland locations. Then, the anticyclone bringing these colder conditions should move off the country around 9 July..
Despite fresh snow falling around the end of July’s first week, bringing cold dry weather suitable for snowmaking, two weeks will go by on Mt Ruapehu before the area is suitable for proper skiing. Operators will be pleased that crowds will already be flocking to beginners’ slopes as Ruapehu becomes attractive again after two relatively sparse ski seasons. Snow on the mountain falls again around 11 July, but may be short lasting.
Central Plateau snowfields should still aim for an opening around 18 July even though anxiety will be building because of insufficient snow that will still be keeping Whakapapa's upper ski runs closed. Around 21 July the lower South Island may receive heavy rain, snow and wind. In Queenstown district and the Wakatipu Basin road gangs should gear up for pulling vehicles out of roadside ditches. Then, two days later, snow again falls on Ruapehu although central North Island motorists trying to reach skifields may be inconvenienced by road closures.
By 11 August, snow and ice may begin to affect the main roads of both islands, from the Desert Rd to South Canterbury. About 15 August, the country should be affected by the first serious bite of winter, with high winds and swells buffeting Cook Strait. Over following days the Desert Rd may find itself facing frequent closures. And by mid August snow levels should be down to about 700m.
At or near 30 August, snow is expected to again blanket Christchurch, with the chance of road closures and power blackouts. The intense southerly flow from this system should then make its way up to the North Island, bringing more snow to the central North Island around 2 September. Most major roads in central NorthIsland will be frequently closed during this period. On Ruapehu, the winds may be seriously strong, with gusts of up to 200kph and full-on blizzard conditions, and this could prohibit safe skiing.
About this time operators will be opening and closing the mountain several times within short periods. Turoa will receive one or two days of good snow but blocked roads will make the facilities and slopes inaccessible. Snow should fall to about 800m. This cold blast with its accompanying storm conditions will continue to affect the country until a general clearing around 4 September.
But then on 17 September for the second time in three weeks, Christchurch could receive light snow flurries. North Canterbury may get steady snow falls which settle at higher altitudes. As the moon approaches southern declination on the 22 September; Northland, Coromandel and western Bay of Plenty may receive an unexpected drenching of rain
By the last week in September, dry weather and sunshine will cause many to believe that an early summer has arrived. Then from mid October onwards, come four weeks of weather contrasts. Northland will become very dry, also the north of the South Island and central Otago. But the southern half of the North Island may be unusually wet.
Because of the late winter, snow operators in the North Island would be well advised to run the season late and close around mid November, although snowfalls are expected to continue falling on the mountains beyond November.
It seems that each year sheep farmers are plagued by lambing losses. This year, with the last wintry snap due around mid September and most frosts gone from most of the South Island by October, in parts of Southland and Otago they may linger a bit longer – with rain as well. Sheep farmers should keep ewes and new lambs in more sheltered areas until at least mid-October to play it safe and minimise stock loss.
For our comprehensive snow reports for all New Zealand and Australian skifields, click http://www.predictweather.co.nz/ArticleShow.aspx?ID=388&type=home
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