Wet, cloudy summer predicted

Press, 27 November 1986, Page 1

Wet, cloudy summer predicted

DAVID CLARKSON

By Np

New weather indicators support a prediction by the Lincoln College meteorologist, Dr Neil Cherry, that New Zealand can expect a summer that is wetter and cloudier than average. There will be many fine, sunny days, but the summer’s rainfall figures may follow this month’s pattern: sudden, heavy falls that push the figures above the average. Dr Cherry made his prediction several weeks ago, and now October’s detailed satellite data point to a likely El Nino effect in the eastern Pacific. That effect brings warm equatorial water into contact with the cold weather system from the Andes mountains of South

America, disrupting the region’s fishing industry and causing storms. The last time it happened, there were marked effects in New Zealand — a stormy, wet winter that included the 1983 Southland floods — but the effect is expected to be weaker this time. The effect has been given the Spanish name El Nino — “the child,” referring to Jesus — because it usually happens at Christmas time. The warm water which tends to gather in the west equatorial Pacific has been found moving eastwards, and there has been a weakening of the ' easterly trade winds. Both ( factors point to another El ' Nino summer. ‘ When that happens, the 1

warm equatorial water displaces the cold current which comes up the South American coast, rich in nutrients and organisms

that promote fish and bird life. The storms created by the warm water lead to slips and mudslides along the coast. In 1982-83, the biggest El Nino event of the century occurred and there was extensive damage and loss of life along the South and North American coasts. Severe storms hit California and in the affluent coastal suburb of Bel Air many houses were destroyed. In New Zealand there was a stormy, wet winter that followed on two years of drought in Canterbury. Dr Cherry believes the weather statistics show that this summer could be similar to the 1979-80 summer. Through the spring there have been frequent

depressions crossing the Tasman and bringing rain. They were responsible for a long run of dismal week-ends because they were on a seven-day cycle. Figures also show that the relationship between the pressures at Darwin and Tahiti is similar to that of 1979. Dr Cherry expects higher than average rainfall during the summer, but he says there is no prospect of endless bleak weather ahead. He said that in January, 1980, 135 mm of rain fell, a figure well above the monthly average, but 109 mm of that fell during a storm on January 2. "What we are suggesting is not that there will be a lot more rainy days

but that the days on which rain falls will give more than average. “Most people don’t realise that for the last seven Januarys, on average more than half the monthly rainfall fell on one day,” he said. “The first three months of 1980 were also cloudier than average, with lower than average daytime temperatures, but higher than average night-time temperatures as a consequence of the cloud. “That is the kind of weather that will typify the coming season. There will be plenty of sunny days, but more cloud than average. That will keep some of the days cooler but the nights warmer,” Dr Cherry said.