SA - FINE WEATHER FOR THE MOST PART THIS WEEK, RAIN NORTHWEST, RAINFALL CHANCES COMING UP NEXT WEEK.

The ridge that is bringing the fine weather this week to areas away from the northwest where widespread rain is underway from a weak trough pushing into the state from WA. The moisture is expected to be undermined by the high that has slowed down in the Bight. So rainfall from the northwest will weaken and erode overnight and into Thursday and areas of high cloud is the only remaining feature from the event.


Dry weather with cold nights and sunny days are forecast for the remainder of the week and into the weekend should feature. There may be a stray shower or storm over the eastern areas bordering NSW with moisture moving in from the easterly winds feeding on top of the high pressure system. But with the ridge so close the only impact will be above average temperatures both day and night.


Next week a stronger cold front that passes through the SWLD should move into the Bight and weaken somewhat, battling the strong high in the southeast. The front will be supported by another wave of unsettled weather pushing northeast through the Bight, meeting the moisture coming in from the northwest and we should see a more organised batch of rainfall passing through the state.


This looks to be the best chance of rainfall for the state for weeks.


Rainfall looks to stick around into the end of next week with showery weather to follow with colder southwesterly winds. Some of the coldest weather this season is forecast to move through to finish the month with light falls to follow the moderate rainfall event.


Let's take a look

FORECAST

Rainfall Next 10 Days

Rainfall is forecast to be confined to the northwest districts over the coming 24hrs with moderate to locally heavy falls in very remote areas expected to ease later tonight and clear Thursday as ridging strengthens throughout the state. The moisture over the eastern parts of the nation will be transported from the broad easterly flow and there could be some moisture being left over from the current event in the northwest stalling out there. Next week, the high in the southeast should begin to move further east leading to a northwest flow developing. A stronger front over WA will move closer to the region from mid next week and a deeper moisture surge from the Indian Ocean is forecast to interact with the front pushing east with a band of rain developing over the state from west to east. Some moderate falls are possible near 20mm for some locations. Behind the front, a colder showery flow will continue with a westerly wind regime. A more winter time pattern is forecast to stay in place for the start of June it appears.

The wave of low pressure will eventually sweep in from the west and link into moisture, and while we may see patchy rainfall spreading through from west to east, we could see modest accumulations over a number of days, leading to hopefully many areas seeing more than 10mm through this period, possibly double of that.

Frost Risk Forecast - Thursday to Saturday.

The frosty nights start tonight and continue through to the weekend with some pockets about the ACT and Southeast of NSW into far eastern VIC, looking at the first severe frost of the season. Once we get the northeast flow developing with moisture being drawn in over the weekend, this will lift overnight temperatures and fog areas will replace the frost followed by more lovely sunny weather.

MEDIUM TERM FORECAST

May 25th-June 1st, 2022

Rainfall Anomalies

There is more agreement that once we lose the strong cold front and rainfall at the end of next week through the southeast that further showers will follow in a westerly wind regime over southern Australia but seasonal expectations for now. The weather turns wet again from the northwest of the nation through to the southeast with some chance of further above average rainfall likely for the interior of WA, through SA and into western NSW possible. Further rainfall knocks on the door over the southwest of WA during this time as well.

Temperature Anomalies

The warmer bias strengthens over the east with the northwest flow strengthening ahead of a series of cold fronts. The western interior still cooler than normal with the westerly wind regime starting to progress into SA through this period with that expected to move further east during the end of the month into early Winter. So, this could be the last few days of 20C+ weather over a widespread area in the south and east until about September.

DATA - Refer to video for more information


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

More information can be found in the video tonight to break down the quite volatile picture that is giving you the larger rainfall spread right across the nation. I will have more in the models and rainfall update coming up from 8pm EST.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The dry cold shift over the southeast will lead to areas of frost tonight with some of that severe in places. Deeper moisture spreading through from WA into SA hits a brick wall and little rainfall will move beyond where it is right now, though high cloud will drift across the nation. Deeper moisture coming in via easterly winds will feed an upper trough over QLD bringing heavy rainfall from the weekend before clearing, but showery warm soupy easterly winds continue into next week. Next surge of deep moisture from the Indian Ocean reaches the west of the nation Sunday and traverses the state before moving into the Bight along a weakening cold front. Another surge of deep moisture reaches the west of the nation again on Wednesday next week and once again later next week with one or both of these waves to spread rainfall chances across the nation from west to east.

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 Euro - 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

A closer look in - rainfall numbers will continue to bounce around for the inland and hence why there is not much change to the charting from me tonight but certainly keep abreast of the forecast notes and videos morning and night to follow the trends. This will change from run to run so don't count what the yr.no apps etc say as gospel.

More coming up from 8pm EST with a look at the models and rainfall

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