Multiple low pressure troughs occurring simultaneously within a humid airmass is leaving me very busy trying to break down all the risks for most states this week. It is a dynamic and energetic flow pattern within the very humid airmass resulting in severe weather potential and flooding for eastern areas of the nation in particular. But as experienced this week alone, most states have seen severe weather occur, some towns copping a battering.
Lets get straight to it - more details later this morning.
Rainfall Next 10 Days
Rainfall is expected to be extensive, heavy and near record in some locations during the next 10 days. From outback flash flooding in the NT through to flood potential amongst high end severe weather over the east and southeast inland, the rainfall will certainly be front and centre until we get a weather system from the west to clear out the humidity. That may take place from next weekend, but it is not convincing yet on the data sets. Some of the medium term models do reintroduce the wet weather back through the northern and eastern inland of the nation, some even bring the rainfall and thunderstorms back to eastern areas as the flow pattern turns easterly. One way or the other it is a dynamic and potentially damaging period of weather over a vast region of the food bowl. Also this disruptive for logistics, freight and construction.
Thunderstorm Forecast Sunday
Thunderstorms overnight have continued through the morning for some parts of NSW and the ACT with some heavy rainfall and small hail observed. The trough responsible is expected to fire off another strong batch of storms later this morning through NSW, ACT and QLD with severe thunderstorms likely in a broad region. Damaging winds, heavy rainfall leading to flash flooding and large hail all a concern. The storm activity is expected to ease during the evening into a wide area of rain over the eastern third of NSW and QLD before clearing offshore.
Euro 12z - Surface Pressure Pattern and Rainfall - Next 10 Days
The trough from SA that moved into VIC yesterday is now amplifying through NSW and QLD today with severe thunderstorms overnight with heavy rainfall and flash flooding in pockets continuing this morning with the main severe weather window from 12-10pm tonight for much of central and eastern NSW and the ACT. The west will see showers and thunderstorms increasing along another trough which will deepen and spread west through Monday and Tuesday with areas of rain, locally heavy. That trough will form a low within the area of unstable air before being carried east through the state into SA and then the eastern states later this week. Heavy rainfall and severe weather is likely with this feature before it moves away from the nation during the weekend and we see some gradual easing from west to east in terms of humidity and severe weather. So once the low pressure system moves east of your region through mid to late week, your weather drastically changes and the humidity is replaced with cooler drier air for a period. The moisture does look set to return from later in the run, the following week over northern and eastern Australia. Clearly the severe weather event coming up this week is today through Tuesday over the east with a deep trough and the low passing out of WA, through SA into VIC, NSW and QLD during Wednesday to Saturday.
Euro 12z - Precipitable Water Anomalies - Next 10 Days
Exceptional PW Anomalies exist through this outlook and they are increasing for the Wednesday to Saturday feature over QLD, NSW and the ACT, which is cause for concern for farmers and other operations in the Ag industry with flash flooding a very high risk as well as severe weather impacts. The long duration humid and wet spell looks to ease over the weekend with a drier cooler pop of air, but as mentioned yesterday I am not convinced of that just yet.
Euro 12z - Precipitable Water Values - Next 10 Days
You can see the rich deep tropical moisture that is in place, hence the storms pumping out a lot of rainfall, as we saw yesterday through metro Melbourne once again and the ACT overnight with some areas recording close to a months worth of rainfall again. The high PW values are here for the next 6 days but will start to ease from the west later this week before we have a lull in the high humidity around mid month before it returns from the north and east once again. The duration of the drier air in comparison to this humid spell will be short. So perhaps only a few days reprieve. With the values later in the week over the east, once again some locations could get 1-3 month's worth of rainfall.
Euro 12z - Rainfall Accumulation - Next 10 Days
The heaviest of the rainfall is expected to come through the nation with the low pressure system from Wednesday to Friday, but watch out for thunderstorms if you live in the east, from NSW, ACT and QLD in the next 2 days, with the high risk of flash flooding. Then we see the storms are showers increase for inland areas across the nation before the low whips it all into an organised batch of rain and thunderstorms with heavy falls before clearance occurs during the next weekend. We could see a few drier days from the 17-20th of November but I am not convinced just yet.
12Z GFS - Rainfall Accumulation - Next 16 days
Rainfall coverage may ease from the 16-21 November across the nation with a dry slab of air being drawn nationwide but I am not convinced of this just yet - will watch trends.
More coming up soon including a look at the large rainfall and thunderstorm event with the potential for flash flooding in multiple states plus your state based forecasts later on today.