Retrospective - September to November Outlook

Neutral ENSO conditions were predicted in the tropical Pacific Ocean for spring 2011, although in actual fact a weak to moderate La Nina had redeveloped by season end. Mean sea level pressures were (correctly) projected to be above normal across much of New Zealand, although the expectation of weaker westerly circulation than normal over the country was not (a southwest anomaly affected New Zealand during spring, helped along by the extremely windy November).

Predicted rainfall: Rainfall is likely to be normal or below normal for all of the North Island as well as the west of the South Island, and near normal in other regions.

Outcome: Spring rainfalls were correctly forecast over much of the north and east of the North Island, as well as the western South Island. It was a very dry spring, with below normal rainfall in parts of the West Coast, as well as in Buller, parts of Hawkes Bay, Gisborne, the East Cape, central Waikato, north of Taupo, The Coromandel and most of Northland. It contrast, it was wetter than projected (with above normal spring rainfall observed) in much of Southland, Otago, Canterbury, as well as north Taranaki, and parts of Manawatu. Near normal rainfall fell elsewhere.

Predicted air temperature: Air temperatures are likely to be above average in the North Island as well as for the northern South Island, and near average or above average in other regions. Cool spells typical of spring will occur from time to time through the period, especially during September.

Outcome: It was a cooler spring than projected along the West Coast, in parts of Southland, south Canterbury, parts of Marlborough, the Wairarapa, as well as most of the Hawkes Bay across to Taupo and the central Waikato Region. The only regions where above average spring temperatures were experienced were eastern Northland and western Bay of Plenty. Near normal temperatures were experienced elsewhere.