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Lower Derwent 28-day Rainfall Forecast

Sun
Mon
Tue
Wed
Thu
Fri
Sat
24
high
25
med
26
med
27
low
28
high
29
high
30
low
Oct 1
med
2
low
3
med
4
med
5
med
6
med
7
low
8
high
9
high
10
med
11
med
12
low
13
low
14
med
15
low
16
med
17
high
18
low
19
med
20
med
21
med
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 remained stable in recent weeks. There are six main troughs. Currently the most significant troughs are near the longitudes of the southwest Indian Ocean, Western Australia, New Zealand, the south 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 2 October to 6 October, 7 October to 11 October, and 13 October to 17 October. Rain events originating in the tropics and moving south are possible about 13 October to 17 October.
Over Western Australia the strongest cold fronts should occur about 2 October to 6 October, 7 October to 11 October, and 15 October to 19 October.

Issued Sep 22

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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