Checkpoint

Outlook and outcome – November 2004 to January 2005

Rainfall predictions were correct for much of the North Island. There was more rain than predicted in the east of the South Island and southern Wairarapa. Parts of the South Island west coast were drier than expected.

Air temperatures were average as predicted in the southwest of the North Island, but lower than expected elsewhere. South Island temperatures were average or below average as predicted for most places.

Streamflows were higher than forecast in the south of the South Island and lower than expected in some western South Island catchments. Many North Island river levels were in line with forecast flows. Storms at the end of 2004, and December’s high soil and ground water levels, contributed to the high flows.

The outcome maps shown here give the tercile rankings of the rainfall totals and mean temperatures that eventuated for these months. Terciles were obtained by dividing ranked November to January data from the past 30 years into three groups of equal frequency (lower, middle and upper one-third values) and assigning the data for the present year to the appropriate group. (Click to enlarge) As an approximate guide, middle tercile rainfalls often range from 80 to 115% of the historical average. Middle tercile air temperatures typically occur in the range of the average plus or minus 0.5°C.