Outlook - March to May 2013

Atmospheric indicators of ENSO, such as the Southern Oscillation Index (SOI), trade winds, and tropical cloud patterns continue at neutral levels. International guidance indicates that the tropical Pacific Ocean is very likely to remain neutral over the next three months (March-May). Lower pressures than usual are likely over northern Australia, with high pressures south of New Zealand. Autumn temperatures are likely to be above average across the South Island, and average to above average in the North Island. Rainfall for the March – May period as a whole is likely to be in the near normal range. For this tropical cyclone season (November – April), the risk of an ex-Tropical Cyclone approaching New Zealand is expected to be near normal. On average, one ex-Tropical Cyclone nears New Zealand during the season. 

Rainfall for the March – May period as a whole is likely to be in the near normal range for most regions, except for the West Coast of the South Island, where normal to above normal rainfall is likely. Because of the existing soil moisture deficits across the North Island and in the eastern South Island, soil moisture levels and river flows are expected to take some time to recover in these areas.

Autumn temperatures are likely to be above average across the South Island, and average to above average in the North Island. 

Soil moisture levels and river flows are projected to be normal to below normal for the autumn season as a whole for the North Island, as well as the eastern South Island, and near normal elsewhere.

For this tropical cyclone season (November – April), the risk of an ex-Tropical Cyclone approaching New Zealand remains near normal. On average, one ex-Tropical Cyclone nears New Zealand during the season.