The latest in a month-long series of cold fronts to arrive in southwest WA will bring a range of severe weather to the most populated regions within the state starting today (Monday 26 July).
A period of heavy rain as well as the potential for dangerous winds, is expected across southwestern parts of WA from this afternoon, extending eastwards overnight.
The first thing people will notice is intense rain with the potential to cause flash flooding in metro areas between Perth and Bunbury and inland across the Darling Scarp from late Monday afternoon.
This rain is also expected to fall over already saturated river catchments and result in additional inflow into swollen river systems.
Widespread rainfall totals over the two days of 10-20mm are likely to occur southwest of Jurien Bay to Esperance.
The heaviest falls of 30-60mm are likely to occur between Perth and Busselton extending inland across the Great Southern.
Widespread damaging winds averaging 60-70 km/h with gusts to 120 km/h are likely to develop southwest of Bunbury to Bremer Bay from early Monday afternoon extending to southwest of Jurien Bay to Bremer Bay, including the Perth metro area from mid to late afternoon.
Isolated gusts in excess of 125 km/h are possible southwest of a line from Geraldton to Bremer Bay and may develop from mid Monday afternoon and continue through the evening.
This front is expected to be windier than a typical front and is likely to produce the kind of weather that is only seen around twice a year.
Dangerous surf and high tides
Dangerous surf conditions will develop again from tonight for a large part of the West Australian coastline with large swells continuing for the rest of the week. Total wave heights may reach up to 9 to 10 metres on Tuesday between Perth and Albany.
It is highly likely for tides about the southwest of WA to exceed the typical high tide line during this week, particularly on the high tide on Tuesday 27 July along the south coast.
Flood watch current
Heavy rainfall in the Swan-Avon river catchments last week caused areas of flooding which cleared during Sunday. The Swan River at Walyunga peaked at 4.1 metres overnight Saturday into Sunday causing very high river levels in Guildford and Bassendean with the Swan River at Meadow St Bridge reaching 1.5m and causing the entire Swan River Estuary to change colour with high sediment levels.
With further moderate to heavy rainfall expected from later today a Flood Watch has been issued for the Swan, Avon, Murray and Harvey River catchments, with a risk these catchments may experience flooding during the week.
Another strong cold front is expected on Thursday. Perth is already experiencing its wettest July since 2000, and further rainfall later in the week may increase the risk of riverine flooding in the Perth hills and the South West.