NATIONAL WEATHER PICTURE - SUNDAY 4TH OF JULY 2021.

Headlines.


  • Rain and storms moving through the southwest with moderate falls being observed over some locations during this afternoon. A line of storms bringing gusty winds to the west coast as well.

  • The east has settled, the pattern flip seeing a run of drier days for the eastern inland and southeast, with colder nights and sunny seasonal weather.

  • Rain looms again for the eastern inland with a run of cold fronts making their way eastwards towards SA later this week.

  • A cold signal with wintry weather exists into mid month for southern Australia with a negative SAM phase likely to redevelop, tapping into copious amounts of moisture over the Indian Ocean.

A pattern flip is underway as the southeast begins to stabalise with showers beginning to decrease over the southeast overnight into Monday as low pressure moves away, that system helping to push along a blocking pattern over NZ. A strong upper high has been holding up the works for the past week and is likely to lift out from Tuesday.


With that pattern flip, rainfall and a few storms has returned over parts of southwest WA today and some moderate falls have been observed up an down the coast, that rainfall extending inland though the intensity is weakening as the front slides southeast throughout the SWLD.


The long wave trough is anticipated to set up over the southwest of the nation bringing further fronts and wintry weather for the next 10-14 days, with perhaps a brief break later in the week, but another long wave is expected to return later in the week over the southwest. The lead long wave will bring a burst of strong winds and rainfall for the eastern inland as that runs into better moisture over the east.


The cold signal remains strong for the remainder for the southern parts of the nation with a westerly wind belt with short and long waves passing through at a rate of knots, bringing those temperatures down and increasing coastal rainfall and mountain snowfalls. A real classic set up is being signaled by the models.


National Satellite Picture - Valid Sunday 4th of July 2021.

Dynamic weather systems on both sides of the nation with the east clearing with a strong trough moving slowly east. A cold pool and low over Bass Strait continues to move east and weaken. A strong front and associated deep low offshore the southwest coast driving rain and thunderstorms this afternoon. In between the systems, it is dry and clearing with a cool airmass under high pressure.

A band of rain and thunderstorms moving through the west coast and adjacent inland has produced moderate falls and quite a bit of lightning today with gusty winds. The thunderstorms are in the process of weakening as they track inland with areas of rain with some moderate falls extending to the Wheatbelt this evening. Widespread showers to follow over the southwest with a gusty westerly wind regime and cold air racing in. Small hail and thunder is possible

A cold pool associated with a weakening low pressure system is driving showers and gusty winds throughout the southeast with small hail and thunder about coastal areas this afternoon and this evening. The showers will ease overnight and clear later Monday as high pressure moves in from the northwest.

Temperatures - Valid 5pm EST Sunday 4th of July 2021

Drier air dropping the day time temperatures today after a warm and humid week nationally for July. Seasonal weather returning to large parts of the north with a nice push of drier southeasterly winds pushing northwards. Fine over the east and drier in a westerly winds. Cold throughout the southeast with a cold airmass drifting through but with dry air, mostly cloud west of the divide through NSW. A cold front pushing through southwest WA bringing a large temperature drop.

A closer look at the first front passing through the southwest with gusty winds and cooler weather filtering east with that cold front. Temperatures have rebounded a little after the front along the far southwest coast but they will drop with colder air about to arrive this evening with gusty showers and storms.

Radar - Valid 5pm EST Sunday 4th of July 2021

An organised batch of showers and storms rolling through with the front with patchy rainfall extending inland ahead of the front. Moderate falls have be observed in towns and communities along the west coast. 10-20mm has been recorded so far with 15mm at Perth.

Widespread showers developing east of Melbourne with a trough passing through, rotating around a weak low offshore to the south. Some of the showers have been rather wintry with small hail about the coast. Showers will continue tonight before easing during the morning and clearing tomorrow night.

Rainfall for the next 10 days - Valid Sunday 4th of July 2021.

The focus of the rainfall clearly over the western parts of the nation with a long wave parked out west driving widespread rainfall through the west. Some of that instability will come into the eastern inland later this week and link up with limited moisture to produce areas of rain Friday and Saturday. The the series of frontal activity increases for southern Australia later next weekend into the early the following week with mid month looking wintry, wet and cold.

00z GFS Rainfall for the next 10 days - Valid Sunday 4th of July 2021

Heavy rainfall exceeding 100mm expected through the southwest with moderate falls to 50-60mm pushing inland over WA. A solid rainfall event over the eastern inland may deliver another months worth of rainfall if this is right, through the eastern inland of NSW and into northern VIC with a trough moving in later this week, utilising moisture coming out of the north. Showers increasing later about coastal SA and extending into VIC with moderate falls for the southeast of SA.

00z Euro Rainfall for the next 10 days - Valid Sunday 4th of July 2021

Very wet for the west coast with the frontal barrage. Quiet over the east before that rainfall develops with the first trough making it through to the east on Friday. Again the models have swapped tonight again with Euro and GFS not in agreement at any point but showing both rainfall spreads at one time or another. Note the rainfall coming up for inland SA. Some improving signals in the day 8-10 window too.

00z CMC Rainfall for the next 10 days - Valid Sunday 4th of July 2021

This model does pick the rainfall over WA well with similar rainfall spread to GFS, but otherwise has struggled with the events over the east and likely to be an outlier in this evenings run.

Model discussion and analysis - Valid Sunday 4th of July 2021


00z GFS 500mb/18000ft flow pattern

00z GFS Surface pressure pattern and rainfall distribution


Monday 5th of July 2021

Strong upper high over NZ blocking the flow pattern still overnight and into Monday with the low and trough over the east slowly clearing off. Strong long wave slowly moving through the southwest of the nation thanks to the slow pressure pattern across the southern latitudes. Zonal flow establishing over northern Australia however slack pressure pattern upstairs.

Showers clearing over the southeast later as a large high moves into the southeast and eastern inland, clearing conditions, but bringing colder nights and sunny weather. The main weather action will be over the southwest of the nation with showery windy weather, local hail and thunder overnight clearing to the south coast on Monday, but remaining cold with high wind chill.

Tuesday 6th of July 2021

Strong long wave parked over the southwest continuing to bring wintry weather to the southwest and another front to pass through. Upper high over the southeast moving further to the southeast, thanks to the blocking pattern over NZ finally breaking down. Heights about where they should be over the north.

Strong cold front rising from the southwest of WA bringing an increase in showers with areas of rain developing for the southwest with moderate falls returning. Thunderstorms and hail to follow at night about the coast with gale force westerly winds. Elsewhere it is settled with high pressure controlling the scene with cold nights and fog and frost returning to the inland through most states. Seasonal weather conditions.

Wednesday 7th of July 2021

Strong upper trough over WA with a long wave passing through the western inland with further wintry weather. Upper high over the southeast continuing to move eastwards with a more mobile pattern developing. A weak trough lifting off the east coast.

Widespread showers with local hail through the southwest with a gusty southwest to westerly flow continuing, though with a high offshore, conditions should start to ease later in the day. A high over the southeast continuing to move through but ridging back over the central interior, controlling large parts of the nations weather. A few showers just offshore the east coast may come onshore with a wind shift to the southeast later in the day.

Thursday 8th of July 2021

Strong upper trough connected to the long wave will begin to move through SA, but with a lack of moisture just thick cloud expected for now, showers developing along the southern SA coast later heading into the YP later. Upper high over the east will lift eastwards with conditions warmer and becoming windy. A brief clearing trend for WA.

High pressure moving into the Tasman directing onshore winds over the eastern inland where moisture will create a few showers. A strong front moving through Bight will continue to weaken, but strong winds ahead of this system will lead to above average temperatures. The front itself likely to trigger a few showers and a thunderstorm for the west coast of SA which will likely head east later. Showers easing over the west coast and clearing later as high pressure moves in, easing the wintry spell.

Friday 9th of July 2021

Strong upper trough moving through central Australia will begin to move into the eastern inland and interact with moisture allowing a productive rainfall event to break out over southern QLD into NSW and possibly VIC. Placement of this is still yet to be determined. Weak ridge moving east through WA ahead of another long wave trough arriving later.

Rain breaks out over the eastern inland with a few storms, some moderate to heavy falls are possible with this feature moving through the region. But the risk of heavy falls leading to flooding is low with the system moving at pace. Another front arriving in the southwest bringing windy weather and showers later in the day. Showers along the east coast will continue during the morning before easing later. Fine weather over the north. Marginally unstable through SA and VIC where a few showers are possible over a broad area.

The system quickly dives to the southeast over the inland regions of NSW where it interacts with cold air, a low may form in response to this, with rain extending over the southeast inland and ACT, falling as snowfall over the Alpine areas. Rain and showers for the east passing east with a trough moving east with the low. High pressure clearing the eastern inland and keeping the south dry. Showers increasing over the west coast with a gusty southwest to westerly flow.

Saturday 10th of July 2021

Trough passing to the east of NSW with an upper low offshore. Weak ridge coming through SA at pace with yet another long wave parked over WA producing the next round of strong winds and wintry weather. Fine weather over the north with a tad more humidity for coastal areas.

Deepening low off the southeast coast of VIC will continue to drive showers over southeast NSW and eastern VIC with possible moderate falls. That focus will clear during the day. High pressure ridge keeping the bulk of the nation calm, cool and dry. Winds increasing over SA with a front approaching later in the day with increasing clouds. In between fronts over WA with another front arriving at night. Fine over the north after possible morning showers.

Sunday 11th of July 2021

Upper trough moves away from the east coast. The flow pattern beginning to strengthen over southern Australia with multiple waves embedded in that flow. A shortwave passing south of SA during the day and a longer stronger wave passing over WA later in the day.

Showers about coastal SA extending into VIC with a shortwave front. This will bring more wind than rainfall at this time. High pressure running on the conveyor belt will rotate through QLD quite quickly. A strong front about to launch into WA with a band of rain and thunderstorms, potential for severe weather with this event.

Wednesday 14th of July 2021

Strong winter pattern continues to be placed for mid month over southern Australia with multiple fast moving fronts embedded in the flow causing gales and cold weather with well below average temperatures. Fine over the north with an upper high and above average temperatures possible over the NT and WA.

One long wave would of brought a showery windy mess through the southeast the day prior, it clears off the NSW coast, a shortwave follows with showers through coastal SA and VIC/TAS. A long wave moves over WA once again with rain and storms, and moisture streaming into this feature may bring rainfall across the western interior. High pressure over the central parts of the nation, adopting a winter time track is expected to stay firm through the region.

Taking it out to the 17th of July, and long wave is now parked over the south and southeast with a soup bowl of lows on this particular run and frontal weather keeping the wet and wintry weather going over the south and southeast, while the west eases in wintry conditions as high pressure calms the pattern down. But this is 13 days out and will likely change, but gives you a sense of the wintry pattern that is expected to unfold. It will likely be prolonged for southern parts of the nation.


Lets compare the Euro run with the GFS this evening to see how the signals are looking through the short term.


00z GFS Rainfall and Surface Pressure Pattern the next 16 days

Good agreement of the timing of weather systems throughout the nation in the coming 10 days, just placement of the eastern system still up for debate. The long wave trough then moves east over southern and eastern parts of the nation into mid month sparking the coldest stretch of weather so far this winter and more rainfall for coastal areas and adjacent inland. Heavy snowfalls are likely under this scenario.

00z Euro Rainfall and Surface Pressure Pattern for the next 10 days. Good agreement with GFS in the timing of systems. Where the models diverge is with the moisture coming in from the northwest during next weekend with rainfall finally possible under this scenario for SA.

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