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Roper-McArthur 28-day Rainfall Forecast

Sun
Mon
Tue
Wed
Thu
Fri
Sat
27
med
28
high
29
high
30
high
31
med
Jan 1
med
2
3
4
5
med
6
low
7
8
9
10
11
12
13
14
15
low
16
17
low
18
19
20
21
22
23
Chance of rainfall within district
nil
< 25%
low
25% to 50%
med
50% to 75%
high
≥ 75%

Issue Notes

The hemispheric long wave pattern has been relatively fast moving in recent weeks. There are four main troughs. Currently the most significant troughs are near the longitudes of the southwest Indian Ocean, Western Australia, the south Pacific, and South America.
Summary:
Over southern and eastern Australia the cold front events with potential to bring widespread rain are now expected about 17 January to 21 January, 21 January to 25 January, and 26 January to 30 January. Rain events originating in the tropics and moving south are possible about 31 December to 4 January, 5 January to 9 January, and 21 January to 25 January.
Over Western Australia the strongest cold fronts should occur about 3 January to 7 January, 17 January to 21 January, and 24 January to 28 January.

Issued Dec 26

Forecast Explanation

This forecast is produced by a multi-model ensemble consisting of dynamical atmospheric models, which are forced by the latest observed atmosphere, ocean, land and ice conditions. The models are designed to simulate features of the real atmosphere, including the daily movement of long and short wave patterns in the Southern Hemisphere.

The future probability of rain in each district is estimated using output from the multi-model ensemble, combined with historical information about the difference between the model forecasts and observed rainfall.

In this deterministic framework the skill of the forecast tends to decrease with time, however the forecasts are updated daily to provide the latest estimates of rainfall probability out to 28 days.

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