“A pause before El Niño”
NIWA has published its climate outlook for the next three months, and the gist of it is that its going to be a ‘fairly typical spring’. Both temperature and rainfall are predicted to be near normal in all regions.
However, sea level pressures are going to begin the change towards El Niño conditions, and these will bring enhanced westerly winds sometimes.
The full report, with tables, can be found here, but the text has also been reproduced below.
Overall Picture
Temperature:
Air temperatures are expected to be near average in all regions. Sea surface temperatures near New Zealand are likely to be somewhat below average through August-October.
Rainfall, soil moisture, and stream flows:
Rainfall, soil moisture levels and stream flows are likely to be near normal in all regions.
Regional predictions for the next three months:
Northland, Auckland, Waikato, Bay of Plenty:
Average temperatures are likely. Normal rainfall, soil moisture and stream flows are likely for the season as a whole.
Central North Island, Taranaki, Wanganui, Manawatu and Wellington:
Average temperatures are likely. Normal rainfall, soil moisture and stream flows are likely, averaged over August-October.
Coastal Canterbury, East Otago:
Average temperatures are likely. Normal rainfall, soil moisture and stream flows are likely.
Background
The equatorial Pacific ocean has moved into an El Niño state (with the atmosphere still to adjust), and El Niño conditions are likely to persist through the rest of 2009. Only weak impacts are expected over New Zealand in the coming three month season.
As the circulation near New Zealand begins to respond to El Niño conditions in the tropical Pacific, we would expect to see a shift to more frequent south-westerlies in the spring. Depending on the intensity of the El Niño, this would suggest a heightened risk of drought in northern and eastern regions over late spring and summer, following a good start to spring (with soil moisture levels likely to be near normal in all regions).