MOISTURE WATCH MEDIUM TERM

Weather still holding some interesting signals for mid month with a lot of moisture circulating through the northern half. The south will be sitting under high pressure, however with the high located further south it will allow for moisture to be drawn in over the eastern inland via easterly winds. Something we have not seen for a while.


The northwest is also seeing an influx of moisture this week with a surge coming out of Indonesia ahead of cold fronts. But the moisture is somewhat decoupled from frontal weather over the southern states, so it won't be lifted into widespread areas of rain at this stage.


For the impacts of short term moisture you can check the national wrap this morning that goes into the impacts of frontal weather this week for southern and eastern areas of the nation.


Lets have a look at the following week taking us through into mid month.


Moisture Watch for the period August 15-22 2021.

So while we are dry there are pockets of moisture and lower pressure to watch.


The data sets


GFS 18Z M - Precipitable Water Anomalies next 16 days

The model is largely unchanged with its distribution of moisture over the second half of the period displayed. You can see the moisture building on the northern flank of the high pressure belt over southern Australia and being kept over the nation during mid month. We just need to see a trough form in the region and rainfall will break out. There are hints of that occurring over the eastern inland parts of QLD and again through WA, but this changes run to run. And will continue to do so, but once again the signal is unchanged for the period.

Euro 12Z M - Precipitable Water Anomalies next 15 days

No real change from the Euro model, showing that moisture wafting around mid month onwards, but it is a little drier than yesterday. Good agreement surrounding the southern states sitting under high pressure and easterly winds dominating the northern half of the nation which is important to see that moisture increase further.

CMC 12Z M - Precipitable Water Anomalies next 15 days

This model is the wettest out of the major three, and shows deeper moisture being utilised across the nation thanks to troughs of low pressure. So this model shows that impact of lower air pressure with the moisture. Widespread rainfall would develop.

GFS 18Z M - Precipitation for the next 16 days

Rainfall bias is shifting towards the eastern inland of NSW and southeastern inland areas with frontal weather picking up moisture and then an inland trough over NSW and QLD seeing rainfall break out next weekend (that remains to be seen). Note the moisture bringing up the rainfall totals in easterly winds for the eastern seaboard. That signal is increasing. Build up conditions over northern parts of the nation may introduce an early taste of build up.

Euro 12Z M - Precipitable Water Values next 15 days

Rainfall bias also shifting to the eastern side of the nation with weaker signals coming through central parts of the nation. This model is the driest out of the 3 but it does show the east coast getting wetter each run, supporting the potential for that positive SAM phase to develop and if that does occur, then widespread rainfall is possible over inland QLD and NSW. Will keep an eye on the upper trough over the eastern inland this time next week.

CMC 12Z M - Precipitable Water Values next 15 days

This is the wettest model still and this shows when lower air pressure dominating the nation mid month onwards. This is the least likely outcome but shows the potential when the low pressure is involved with the moisture that will be pooling over the nation mid month onwards.

So it may be benign for now, but again make the most of the drier phase of weather for the nation, because these periods will be few and far between through the remainder of the year.


I will have more details on the severe weather season coming up next week and a look at the flood risks this spring each state as well.


118 views0 comments