Rain will fall in every Australian state and territory this week as the blocking high pressure pattern that has dominated Australia’s weather over the past two months finally breaks down.

An upper-level low pressure system interacting with a feed of tropical moisture will cause rain to spread over Australia from west to east this week. This dynamic system could also produce thunderstorms, hail and snow.

This week’s wet and stormy weather will mainly target WA from Monday to Wednesday, before spreading across central and southern Australia on Thursday, and then eastern Australia from Friday into the weekend.

A second rain-bearing system could also bring follow-up rain to parts of WA from Saturday or Sunday.

The two systems combined should soak about 70 to 80% of Australia, and some parts of the country could see rain every day this week.

Nationwide soakings like this have been prevented over the past couple of months by stubborn high pressure systems sitting near southern Australia. However, with that blocking high pressure pattern finally breaking down this week, we are going to see the first northwest cloudband of the season and some decent rain in every state and territory.

The maps below show how much rain two different computer models are predicting in Australia this week.

Images: Forecast accumulated rain this week, according to the ECMWF-HRES (top), GFS (bottom) models.

While there is good agreement between forecast models that there will be widespread rain in Australia this week, there is some uncertainty regarding where and how much rain will fall towards the end of the week.

Some models predict a deep trough or low pressure system, possibly an east coast low, generating heavy rain in eastern NSW on the weekend. However, some other models do not have the same system or associated heavy rain on the cards.

Similarly, there is some model disagreement regarding how much rain will fall over WA on the weekend with the follow-up cold front.

Given this model disagreement, it’s too early to know which areas of Australia will see the heaviest rain this week, particularly beyond Friday. What can be said though is that part of every state and territory will get some wet weather in the next seven days and there is potential for flooding in some areas.

Be sure to keep a close eye on the latest forecasts and warnings throughout this week to get the most up-to-date information on this system.