Severe Weather: Cyclone to Form Off WA Coast Saturday

And we can see that here with these dark blues, and whites showing that we have sustained convection around the centre of this system. And that tells us that this low pressure system is intensifying, and we're likely to see it continue intensifying as we move through tonight into tomorrow, likely becoming a category one system on Saturday morning.

So let's look at that in more detail. Firstly, in anticipation of this system becoming a cyclone, we have issued Cyclone Warnings and Watches. Firstly, we have a Cyclone Warning current from Pardoo Roadhouse all the way to Whim Creek. And that does include Port Hedland, with a Cyclone Watch current from Whim Creek all the way down to Exmouth Gulf. And that does include the communities of Karratha, Dampier and Onslow.

Now, if you live in these warning areas, that means we can see gales 64 km an hour or greater in the next 24 hours. While in the watch area, we could see those sustained gales in the next 24 to 48 hours.

So let's time this system out. So we're going to see it intensify overnight. And then tomorrow morning we're likely to see it becoming a category one system off the coast of the Pilbara. And that's going to bring some showers and gusty winds to those coastal areas. But it's highly dependent - if it is closer to the coast, we're going to see heavier rain, stronger winds, but a weaker system. But if it is further offshore, we're likely to see a stronger system, but less impacts on the coastal areas of the Pilbara.

So that's why it's vital that you stay up to date with the latest forecasts and warnings, if you live in this area today, tonight and across the weekend.

Then as we go through Saturday, it will continue to intensify into a category two system as it gets to the north of the Dampier and Karratha area. And then it's going to parallel the coastline as it heads towards Onslow, and then maybe start shifting south as we get through Sunday night. And that's going to bring heavy rain, damaging to destructive winds and flooding to this part of the coastline of WA. So make sure you stay up to date with that. And we'll be issuing track maps every few hours through the entire weekend.

So let's look at all of this in more detail. Firstly, rainfall. We're going to see widespread rain and thunderstorms impacting our coastal areas tomorrow, with thunderstorms extending to our inland areas. Then Saturday night and Sunday, as it gets closer to the coast and intensifies, we're going to see more widespread heavy rain and thunderstorm activity through much of the western Pilbara and into even northern parts of the Gascoyne as we get into Monday night and into Tuesday morning. So we're watching that closely as it heads south.

In anticipation of all this heavy rainfall we are likely to see widespread 50 mm to 100 mm for our coastal areas. But it's once it turns south and gets closer to the coast, we're going to see that more widespread, 100 mm to 200 mm, with isolated falls even higher than that.

And because of that, we do have widespread Flood Watches current for much of the Pilbara, extending well inland, and much of the northern and western Gascoyne areas as well, as that rainfall numbers are likely to lead to flash and riverine flooding in these areas as we move through Sunday and Monday. So that's going to impact travel, possible isolation, and all the dirt roads will become impassable in these areas.

So just to reiterate, tropical cyclone likely to develop to the north of Port Hedland as a category one system Saturday morning, intensifying to a category two Saturday night, and then swinging down to around the Exmouth Onslow area as a category two system as we get into the Sunday night, Monday morning timeframe. And the impacts on the coastline are highly dependent on the exact track and intensity of this system.

So if it moves further offshore, it'll be stronger, but less impacts until it crosses. If it's closer to the coastline, we're likely to see more rain and wind, but maybe a weaker system.

So with all that in mind, it is vital that you stay up to date with the latest forecast and warnings via our website, app and social media. Keep updated with the track maps onshore, track the cyclone on radar, and we'll continue to keep you updated here at the Bureau.