NATIONAL WEATHER WRAP - SATURDAY 31ST OF JULY 2021

Headlines


  • Weather remains gusty and mild through much of the southeast, tending warm to hot over northern NSW and into southern QLD with a northwest flow.

  • Showers increasing for parts of SA this morning with the first in a pair of cold fronts passing through the region over the coming days.

  • Rain developing for parts of VIC and southern NSW this afternoon into tonight with a storm risk.

  • Severe weather continues for parts of southwest WA with well below average temperatures.

  • Well above average temperatures for parts of the NT and QLD through northwest WA continue.

Satellite Imagery

Two strong cold fronts embedded within a long wave trough that is now moving through the Bight region on Saturday. A strong cold front coming into SA with areas of rain breaking out in the battle zone. Another front southwest of WA will bring yet another strong burst of showers and thunderstorms this afternoon with the potential of damaging wind gusts. The north and east remain hot and dry today with temperatures into the low and mid 30s for western and southern QLD. The warm and moist air will clash with the colder and drier air over the coming 24hrs. That will see rainfall break out through parts of southeast SA and most of VIC by tonight. The rain then moving into inland NSW Sunday with light to moderate falls.

State of play for Saturday.

Rainfall next 10 days

Rainfall remains unchanged for the coming 10 days, I am pulling numbers down over the southwest as the last front approaches today and the southwest will see less rainfall in future updates. The rainfall over the southeast has largely unchanged this morning from last night with rainfall developing this weekend, mainly light to moderate falls. The rainfall for QLD is connected to the pattern flip with easterly wind redeveloping as high pressure moves further south over the southern states. An upper trough is expected to move into Central Australia later next week, and this is what is helping to produce rainfall on some models and not on others. This will continue to chop and change over the coming days


12Z GFS Upper Air Pattern for the coming 16 days

The upper flow pattern remains fast flow for the coming 5 days with the upper ridge beginning to break down over the northern half of Australia. Note the weak upper trough that cuts through the upper ridge over inland NT and into southwest QLD later in the week. IF that system can deepen and time itself well interact with the moisture in the easterly winds that will see showers develop over the northern inland and showers increase across the east coast. Elsewhere the westerly wind belt is heading south and high pressure looks to come over the southern states setting up a clearing trend later next week and into next weekend. A new front over WA in around 8 days time could start to bring in another tropical infeed of moisture with a band of cloud and rain moving over inland WA and then southern inland parts of the nation into the medium term.

12Z GFS Surface Pressure Pattern for the coming 16 days

You can see that fast flow pattern eventually retreating to the south and east with the pattern flipping and high pressure replacing the low pressure over the south and the upper high over the north breaking down and more low pressure being allowed to develop over northern Australia in the medium term. The heat troughs are likely to form in this period as well with temperatures well above average and this could also support some pop up showers and storms next weekend. Showers developing over eastern QLD and Cape York through to Central inland QLD next weekend is with an upper trough and the next rain band over WA is with the next front in about 8 days time. After that strong high pressure is being touted to control the nation but this could still change given it is medium term forecasting, but I will point out, high pressure coming into the southeast and at that strength will see a lot of moisture return to the eastern inland of QLD and NSW.

12z GFS Rainfall for the coming 16 days

Light falls for eastern QLD through this period is the stand out shift away from the westerly wind dominance. Numbers over the southeast of the nation is connected to the westerly wind regime which will shift southwesterly next week with showery weather to continue through mid week. Showers easing over the southwest of the nation with a 4 day break in rainfall for most of the inland before the next rain band develop during this time next week from the Indian Ocean. Showers and inland thunderstorms for pats of the north of the NT and Kimberly possible as humidity rises.

12z Euro Surface Pressure Pattern for the coming 10 days

The pressure pattern for the coming 10 days is very similar to the GFS version this morning, with the long wave passing over southern Australia with showery windy weather, and inland rainfall developing along the battle ground between the hot and colder air. That rain band will lift north as the trough is pushed along by the second front. Fine weather for most of the north during the coming 5-7 days before moisture returns. So this week the weather will be one of transition and weather usually trends more benign during these times as things reset.

12z Euro Rainfall for the coming 15 days

The Euro reflects that pattern of transition with the north progressively getting more moist as we go through the period. Showers return to the east coast of NSW and QLD through the second half of the period. The bulk of the rainfall over the southern states falls this week with drier weather developing later next week.

12z Euro Precipitable Water for the coming 10 days

The PW Values are still reflecting a cloud and showery 5 days for the south and the east before a surge of dry air comes in as the long wave moves into NZ, providing that colder and drier southwest flow. That will clear out the eastern and southern states with clear skies gradually extending from inland areas to the coast. The west turns dry from mid week as the high noses in, before the moisture returns there quicker later this week into the weekend with another band of rain next weekend, timing to be determined.

This was last night in the medium term looking at the GFS and Euro.


Euro 00z Precipitable Water Anomalies - Monday 9th of August

This mornings run is fairly similar but the moisture is not as deep over QLD with it sitting a little further east. But will watch trends. Very similar over WA, though the front a little quicker this morning, we want the front to not be too fast, to capture as much moisture as possible for areas relying on follow up rainfall for inland SA, VIC and NSW.

GFS 00Z Precipitable Water Anomalies Sunday 15th of August

More weather to come this afternoon.








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