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Perth 28-day Rainfall Forecast

Sun
Mon
Tue
Wed
Thu
Fri
Sat
21
22
23
low
24
med
25
med
26
med
27
low
28
low
29
med
30
low
May 1
low
2
med
3
low
4
5
6
low
7
8
9
low
10
med
11
12
13
low
14
low
15
med
16
low
17
low
18
low
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 six main troughs. Currently the most significant troughs are near the longitudes of South Africa, Western Australia, New Zealand, the southeast Pacific, South America, and the Atlantic Ocean.
Summary:
Over southern and eastern Australia the cold front events with potential to bring widespread rain are now expected about 30 April to 4 May, 14 May to 18 May, and 20 May to 24 May. Rain events originating in the tropics and moving south are possible about 5 May to 9 May, 20 May to 24 May, and 24 May to 28 May.
Over Western Australia the strongest cold fronts should occur about 28 April to 2 May, 15 May to 19 May, and 21 May to 25 May.

Issued Apr 20

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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