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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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- How is rain measured? How is snow measured? How do you calculate the water equivalent of snow?
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- 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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A very wet weekend for southeast Qld, northeast NSW
11:48 AEST A prolonged rainfall event is set to bring large totals to parts of NSW and Qld from Saturday, with possible heavy falls and flooding. A low-pressure system in the Coral Sea, a deepening coastal trough and persistent easterlies will bring moisture-laden air into southeast Qld and northeast NSW will bring days of rainfall to the region. While there is not a drop of rain on the radar over southeast Qld and Northeast NSW on Friday morning, the mass of cloud associated with a low in the Coral Sea will enhance rainfall over the weekend.
- 10:07 AEST Southerly surges across the southeast
- 13:20 AEST Generation gone with the wind
- 11:29 AEST Devilishly dry in Tasmania
- 16:41 AEST Dubai deluge: a year's rainfall in a day
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