Climate Update 100 - October 2007

October

September's climate

Global setting and climate outlook

Feature article

Feature article

Wind chill equivalent temperature

The number of days per week of high or extreme wind chill risk for the years 1972–73 to 2007–08, at Napier.

Loss of body heat from young animals soon after birth is asignificant cause of lamb mortality on New Zealand farms eachspring. Key drivers of heat loss are the ambient air temperature,wind, which increases convective heat loss, and skin wetness,which causes evaporative heat loss.
Weather models can provide estimates of wind chill risk on different time scales, and provide some warning of high risk periods.

September's climate

New Zealand climate in September

Rainfall (click to enlarge).

Temperature (click to enlarge).

September was a relatively benign month with more anticyclones and less wind than normal, and less extremes. Rainfall was lower than normal in many areas, especially in the west of the NorthIsland. Temperatures were above average in many North Island areas.

October

A monthly newsletter from the National Climate Centre.
October 2007 – Number 100
September climate – mostly drier than normal, but near orabove normal rainfall in parts of Northland, eastern NorthIsland, and Otago. Low stream and river flows in manyeastern areas. Above average temperatures in the north ofthe North Island and west of the South Island.
Outlook for October to December – normal or abovenormal rainfall, soil moisture, and river flows in the NorthIsland; normal or below normal in the South Island.

Global setting and climate outlook

Global setting and climate outlook
La Niña conditions have developed

Difference from average global SST (click to enlarge).

Monthly SOI values (click to enlarge).

La Niña conditions have become more developed in the tropical Pacific over the last month. Sea surface temperatures in the equatorial Pacific have become more strongly negative during the month, especially in the east (see map below), and the area of cold anomaly has expanded westward to the Dateline.