Seasonal Climate Outlook: September–November 2008

NATIONAL CLIMATE CENTRE 31 August 2008

Seasonal Climate Outlook: September–November 2008

Change from a wet winter to a more settled spring

The NIWA National Climate Centre says that the upcoming spring is likely to be relatively settled and drier than normal overall, in contrast to the often stormy and wet winter experienced in many parts of New Zealand.

The centre’s seasonal climate outlook for September to November indicates near-normal or below normal rainfalls are the most likely outcome across the country. Rainfall and river flows are likely to be below normal in alpine and western regions of the South Island, including key hydro catchments. Lake inflows typically reach a minimum in September, before rising during the snow-melt season in late spring.

The outlook also says average or above average temperatures are likely in most areas. Mean sea-level pressures are likely to be higher than normal over the country, especially the South Island, with lighter winds than normal.

There is presently no La Niña or El Niño in the Tropical Pacific, and no indication of either La Niña or El Niño developing for the rest of the year.

Overall Picture

Temperature:

Air temperatures are likely to be average or above over the entire country. Sea surface temperatures around New Zealand are likely to remain near normal.

Rainfall, soil moisture, and stream flows:

Rainfall is likely to be near or below normal over much of the South Island, and the north of the North Island, with near normal rainfall elsewhere. Normal or below normal soil moisture levels and streamflows are likely in the north of the North Island and below normal conditions are likely in the south and west of the South Island. Elsewhere, normal soil moisture levels and streamflows are likely.

[Reporters please note: Probabilities are assigned in THREE categories; above average, average, and below average. See end for more explanation.]

Regional predictions for the next three months:

Northland, Auckland, Waikato, Bay of Plenty:

Average or above average temperatures are likely. Rainfall, soil moisture and stream flows are likely to be normal or below normal for the season as a whole.

Central North Island, Taranaki, Wanganui, Manawatu and Wellington:

Average or above average temperatures are likely overall. Near normal rainfalls, soil moisture levels and stream flows are likely.

Gisborne, Hawkes Bay, Wairarapa:

Average or above average temperatures are likely for the three months September-November. Normal rainfall is likely overall, with near normal soil moisture and stream flows.

Nelson, Marlborough, Buller:

Above average temperatures are likely. Normal rainfall, soil moisture levels, and stream flows are likely.

West Coast, Alps and Foothills, Inland Otago, Southland:

Average or above average temperatures are likely. Rainfall, soil moisture and river flows are all likely to be below normal.

Coastal Canterbury, East Otago:

Average temperatures are likely for spring. Normal or below normal rainfall is likely overall, with near normal soil moisture levels and stream flows likely.

ends

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