FRIDAY PM WEATHER - ANOTHER COLD FRONT APPROACHES SOUTHEAST. UPPER TROUGH DEEPENS NEXT WEEK NORTH.

ANALYSIS

A cold front has cleared the southeast of the nation today and the bulk of the country reflects the dominance of the dry air and high pressure with settled conditions for most areas today and quite likely to continue through this weekend.


Another cold front is on the way for the southeast of the country from later tomorrow which will likely provide the next chance of widespread rainfall for the nation, but even that is expected to be within seasonal expectations.


SHORT TERM

But as spoken about at length, the focus shifts to the upper trough that wafts in behind the cold front that moves over the southeast of the nation this weekend and into next week. That upper trough is not being handled properly, hence why the rainfall keeps moving from one region to another over northern WA, NT, QLD and into NSW. This will continue for the next 2-3 days.


Some chance we could see a stronger front surging northwards towards the south or southeast mid to late next week which may set off a cold outbreak with widespread showers and windy weather. But not all models are in agreement with this.


Otherwise, what carries a higher confidence, is the retreating of the westerly wind belt. The dry weather over the SWLD of WA may continue for a good chunk of the short term with only very isolated showers impacting the coastal areas over the southwest.


LONG TERM

The moisture over northern and eastern Australia may linger for the longer term for the end of the month and into early July. The colder and drier air over the southeast may also linger for a period with the high over the Bight remaining slow moving in response to the block occurring over eastern areas of the nation.


That could see warmer weather continuing for large areas of northern and northwestern Australia with an absence of cloud and drier air.


AREAS TO WATCH

The SAM is expected to remain at near neutral values through next week with a brief positive phase and then shift southwards into negative territory once again through July.


The moisture over the northern and northeast of the nation may be enhanced by the easterly flow if the SAM remains positive for a longer duration than what is being advertised right now.


WEATHER VIDEO PM - FRIDAY 24TH JUNE 2022

FORECAST

Rainfall Next 10 Days

Rainfall is tending below average for the period for parts of southern WA and SA where we see high pressure digging in from the west and becoming slow moving over the course of the next 7-10 days. On the northern and eastern flank of the high, there are areas of low pressure and cold fronts/troughs over the southeast bringing widespread showers and storms off and on throughout the period. The above average rainfall signals are still present for northern Australia and will remain there but will shift from run to run. The pattern is of low confidence and will remain so in response to the uncertainty surrounding the development of the upper low over the north and northeast of the country and how long that lingers for.

Now that we are getting the two possible rain events in the 10 day window, I will just do a broad update tonight and then tomorrow before returning to the state based windows on Sunday. The low confidence forecasting as mentioned continues.

This assigns the confidence related to the rainfall spread off the current modelling.

THUNDERSTORM FORECAST

Thunderstorm Forecast Saturday

Nil Thunderstorms at this stage, but watching the potential for cold air to drift into the southeast, that could promote some local hail and thunder. Possibly a storm over the waters north of Australia too.

Thunderstorm Forecast Sunday

Nil Thunderstorms....for now! The upper trough approaching later in the weekend could kick off storms over SA and or QLD through the afternoon so keep watch.

Thunderstorm Forecast Monday

The development of a trough over the northern parts of the nation could start to see scattered showers and thunderstorms emerging later Monday into Tuesday.

Thunderstorm Forecast Tuesday

Thunderstorms are possible over a broad region of the NT and QLD, but the forecast confidence is low, and this will continue to shift as the guidance improves.

Thunderstorm Forecast Wednesday

Thunderstorms are still possible over a broad area of northern and northeastern Australia with a broad trough and deepening moisture but the coverage within this broad zone is uncertain and will likely shift in the coming days. If a strong cold front approaches the southeast of the nation, there is the chance of thunderstorms with the boundary as that moves through.

MEDIUM TERM

July 1st - July 8th, 2022

Rainfall Anomalies

The wet bias is still being held up on most of the broader data sets leading to a wet few weeks for parts of eastern Australia, if the easterly winds and troughs combine in the right region. The drier bias continues for the west, though marginal, may be a signal of a period of quieter weather continuing for the coming 1-2 weeks. Seasonal most elsewhere for now, but with higher pressure moving over the southeast into early July, we could see some drier weather develop over the southeast inland and Tasmania.

Temperature Anomalies

A colder bias is developing on the charts in response to the colder air that is beginning to appear on most of the modelling at the moment, leading to that cold and drier air becoming trapped under a large Winter high over the Bight. If the high remains slow moving in the same region, then most of the country could go from that humid and warmer look that brings the rain, to a colder and drier outlook for the first week of July.

CLIMATE DRIVERS - SOUTHERN ANNULAR MODE - NEGATIVE PHASE EASING.

We can see that the negative SAM is nearly over with a neutral phase likely to develop through the weekend and into next week. Note that the lag impact of the phase shifting is about 3-5 days so you may start to see the rainfall return to the east coast mid to late next week as the SAM shifts into positive territory. The models are struggling with this component too.

DATA - Refer to video for more information and the model comparison and context about all the forecast products you see from me.


00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 2 Weeks

Refer to the video for more context behind the model madness, perhaps seeing a little tightening in the guidance among the models tonight for the north and east but will know more through Saturday and Sunday.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The moisture looks to persist over the northern parts of the nation as we move through the outlook period into the second week of July and the drier and more seasonal air focused over the southeast on the southern side of a high-pressure ridge. The drier than normal weather is forecast to continue over the west and southwest of the nation IF this is right, but it is still not highly certain that the synoptic will allow for the dry bias to continue over the western and northwest of the nation.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z GFS - Rainfall Accumulation - Next 2 Weeks

Refer to the video for more context and analysis and the state by state fly around.

More coming up on Saturday morning. The next weather video is due out on Sunday afternoon and look out for the Summer Outlook for 2022/23 to see where things are heading with a broader overview and much more.

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