Lower Derwent 28-day Rainfall Forecast

Sun
Mon
Tue
Wed
Thu
Fri
Sat
25
low
26
med
27
low
28
29
high
30
high
31
high
Nov 1
high
2
high
3
high
4
med
5
med
6
med
7
8
med
9
low
10
low
11
low
12
low
13
14
low
15
low
16
low
17
high
18
med
19
high
20
high
21
high
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, the Indian Ocean, Western Australia, the south Pacific, 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 29 October to 2 November, 9 November to 13 November, and 25 November to 29 November. Rain events originating in the tropics and moving south are possible about 7 November to 11 November, 11 November to 15 November, and 19 November to 23 November.
Over Western Australia the strongest cold fronts should occur about 2 November to 6 November, 9 November to 13 November, and 26 November to 30 November.

Issued Oct 23

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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The Storms in Sydney on Sunday

14:23 AEDT Parts of the Sydney skyline were lit up by lightening yesterday, as a low pressure trough triggered thunderstorms.

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