Roper-McArthur 28-day Rainfall Forecast
|Chance of rainfall within district|
25% to 50%
50% to 75%
The hemispheric long wave pattern has remained stable in recent weeks. There are five main troughs. Currently the most significant troughs are near the longitudes of South Africa, the southwest Indian Ocean, eastern Australia, New Zealand, the south Pacific, and the southeast Pacific.
Over southern and eastern Australia the cold front events with potential to bring widespread rain are now expected about 2 July to 6 July, 8 July to 12 July, and 14 July to 18 July. Rain events originating in the tropics and moving south are possible about 20 July to 24 July, and 27 July to 31 July.
Over Western Australia the strongest cold fronts should occur about 2 July to 6 July, 10 July to 14 July, and 25 July to 29 July.
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.
After a few cold mornings, the cold days have now started in the ACT.
Snow has fallen across large parts of NSW, including the Blue Mountains, parts of the NSW Central Tablelands, and in the Barrington Tops National Park near Gloucester.
Sydney's run of cold weather has continued today but when can we expect it to warm up? Considering last autumn was the warmest on record the past few wintry days have been a shock to the system for many.