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Understanding the Weather
What is the Nino3.4 Index?
The Nino3.4 Index, similar to the Southern Oscillation Index, is closely tied in with the El Nino phenomenon. Nino3.4 is the average sea surface temperature anomaly in the area bounded by 5N to 5S and 170W to 120W. Changes in sea-surface temperatures in this region are important in shifting rainfall areas across the far western Pacific Ocean. An El Nino event is indicated if the 5-month running average of the Nino3.4 index exceeds 0.4C for at least six consecutive months. A La Nina event is indicated if this average is below -0.4C for at least six consecutive months.
A graph of the Nino3.4 index is updated weekly on Weatherzone, making it easier to track changes in the Pacific Ocean sea-surface temperatures.
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- What does wind chill mean?
- What is relative humidity?
- What is feels like temperature?
- How is the UV index measured?
- How are sunrise and sunset times measured?
- How do I set my barometer?
- How is rain measured? How is snow measured? How do you calculate the water equivalent of snow?
- What are common sources of errors in measuring precipitation?
- What is the dew point?
- Why is wind not always included in the forecast?
- When you talk of a north or northerly wind, do you mean that the wind blows from the north or towards the north? Is this the geographic north of the magnetic north?
- How is a weather forecast made?
- What is the difference between a tropical cyclone, a hurricane and a typhoon?
- Do you have an explanation of the terminology you use in weather forecasts?
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Decent rain en route to bone-dry southwest WA
14:29 AEST Welcome rain is coming to the parched southwest WA this week, possibly including Perth and Bunbury which are both having their driest 7 months on record. Many locations in the southwest will see the driest April on record, with much of this rainfall likely to contribute to May’s totals, as a cold front approaches the state on later in the week. Rainfall and thunderstorms are forecast in the Gascoyne region on Monday afternoon, before shifting to the Central West, Lower West and Central Wheatbelt regions on Tuesday.
- 12:32 AEST Wet week ahead for eastern and southwestern Australia
- 12:14 AEST A quick look at our water storages
- 16:15 AEST Signs indicating Australia's cool season arrival
- 07:00 AEST Bonsoy Gold Coast Pro surf forecast
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