Island Climate Update 68 - May 2006

Update on Pacific Islands rainfall outlook
S Burgess, NIWA

Figure 1. Frequency of correct 3-month rainfall outlooks. A score of 100 would mean that all were correct.

Figure 2. Validation scores for 64 (3-month) rainfall outlooks. This chart shows the percentage of correct forecasts. Scores of 60% or more indicate significantly better outcomes than chance.

Figure 3. ICU rainfall forecast skill, by month. Forecasts issued in February, June, and July have the highest skill.

There have now been more than 60 seasonal rainfall outlooks issued for the Southwest Pacific through the ICU.

Climate developments in April 2006

Outgoing Long-wave Radiation anomalies for April 2006. (Click for enlargement and detail)

The "double ITCZ" structure, usually seen only in La Niña conditions, persisted in April. One region lay north of the equator from the area north of Papua New Guinea extending east across much of the Pacific. Another region extended east, south of the equator, from about Tokelau towards the Marquesas Islands. The SPCZ was displaced much further southwest than average, extending from the Coral Sea southeast toward New Caledonia.

Tropical pacific rainfall - April 2006

Territory and station name
April 2006 rainfall
total (mm)
April 2006 percent
of average

Australia

Cairns Airport
644.8
339

Townsville Airport
204.6
330

Brisbane Airport
15.2
17

Sydney Airport
10.6
11

Cook Islands

Penrhyn
219.2
108

Rarotonga EWS
170.4
81

Fiji

Rotuma
93.0
32

Udu Point
370.6
134

Nadi
114.2
71

Nausori
264.2
74

Ono-I-Lau
196.8
125

French Polynesia

Hiva Hoa, Atuona
189.4
109

Tahiti – Faa’a
229.2
199

Tuamotu, Takaroa
40.6
34

Gambier, Rikitea
192.6
128

Tubuai
125.8
69

Rapa