DRY FOR A FEW DAYS BUT HEAVY RAINFALL DEVELOPING THIS WEEKEND FOR SOUTHERN WA.

Another system is on by to the east, we are dry for a while, but yet another system is lining up the southwest of the nation with a strong cold front expected to sweep through the region, bringing heavy rainfall and thunderstorms from late Friday.


Rainfall for the next 10 days - Valid Tuesday May 25th 2021.


A long wave trough off in the Indian Ocean is expected to link up with tropical moisture over the northern Indian Ocean and combine to produce widespread rain and thunderstorms from later Friday through Saturday and Sunday.


A low pressure system may also form along the front as it slows down, due to a blocking ridge in the east, thus allowing rainfall numbers to pick up over western and southern inland areas of the state, adding to the wet start to the wet season throughout the region.

Surface pressure pattern showing the rain and thunderstorm activity moving into the west coast from Friday afternoon and continuing through Saturday and Sunday with locally heavy falls about. A low is anticipated to form somewhere along the west or south coasts during this time. This will determine the heaviest of the rainfall. This will become clearer later this week. So stay tuned as your rainfall numbers will increase or decrease in line with that. GFS Valid Tuesday May 25th 2o21 - Friday to Tuesday next week.


As a low forms, it's placement, timing, intensity and scale will determine the amount of rainfall that develops and if severe weather unfolds over the weekend. There is some chance of severe weather for southern and western coastal areas this weekend, with damaging winds and heavy rainfall leading to flash flooding the main concerns.


Charts will be issued in response to the severe weather threat as it has the potential to cause some disruption to coastal communities.


With the large amount of tropical moisture being drawn into the region, the rainfall will extend right through to the Pilbara (light falls) and then south and east from there, with once again some areas expecting to receive 1 months worth of rainfall in this event.


Precipitable Water anomalies - Friday through Tuesday next week. Note the low pressure system wrapping that moisture into it's centre, so where that low forms, the wettest weather will be on it's eastern and southern flank. Some wrap around rainfall will be experienced on it's western side as well, if the low sits close enough to the coast. GFS 12z run Valid Tuesday May 25th 2021.


The system then starts to be forced south and southeast during the early parts of next week thanks to that strong ridge in the east, pushing the system south and away from the region. A new ridge likely to clear skies this time next week.


But this will end what has been a very wet month for the southwest of the state. Also inland areas have seen reasonable rainfall. June will continue with the wet trend.


Want more weather information for your region? Email me at karllijnders@weathermatters.org and we can discuss how I may be able to assist.

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