We are hoping for better signals that the rainfall is forecast to increase across SA, with a band of rain developing over inland WA from Tuesday and a broad low-pressure system moving over the SWLD of WA, both systems could merge to see a large cloud band move over southern and western parts of the nation this week.
But once again, this could be interrupted by the high over the southeast of the state with drier air being trapped under this feature and the high deflecting the rain bearing system out west away from the region for now.
This week, the weather should remain mild to warm under the high with that rain shearing off to the southwest of SA. But some better signals may come from later this weekend into next week.
A stronger cold front is expected to move over the southwest of the nation with a band of rain and thunderstorms forecast in SWLD WA during the latter part of the weekend into next week with that system also linking into moisture. Another cloud band should form as a result, that system looking promising for follow up rainfall attempts moving into the following week to end May. That may offer better rainfall chances for the state as we move into next week.
It is normal for the rainfall to increase from late May onwards for SA, with the rainfall usually more productive in the June-September period.
Let's take a look
Rainfall Next 10 Days
Rain free days exist until about early next week where we start to see a broader attempt at rainfall spreading throughout the state. We have a few coastal showers tonight in onshore winds, but it is nothing to write home about given what we are seeing elsewhere across the nation in recent times. The bulk of rainfall for our region should start to approach from Tuesday with a large cloud band developing across the western interior and then forecast to move east and southeast throughout the state, but with high pressure over the state, this will erode anything other than cloud moving through. Another strong cold front with a cloud forming ahead of that feature later in the weekend could provide some better chances of rainfall across the state as we move into the last week of May. These systems are typical for this time of year and heralds the wetter months across SA. This year it is still very likely that many areas will see above average rainfall, even though the falls have been patchy for some in Autumn and many of you screaming at the systems for some decent falls! But it will turn quickly!
Frost Risk Forecast - Tuesday through Friday
A drier airmass is forecast to settle in from Monday and with clearer skies and the high-pressure ridge moving in, there is the chance of frost developing. The peak of frost is forecast from Wednesday and Thursday before easing later this week. For eastern areas the risk is mainly mid-week, and it could be extended to the Flinders and Mid North.
Medium Term - May 22nd-29th 2022
Northwest cloud bands look to continue over the nation with moderate rainfall extending underneath the cloud band. The moisture may merge with moisture from easterly winds in a warm airmass leading to widespread rainfall above the average once again a decent chance over parts of eastern QLD and through NSW. The SWLD with persistent onshore winds and frontal weather moving through bringing bursts of showers and colder conditions. Generally seasonal rainfall is forecast over southern parts of the nation with light to moderate rainfall.
A warmer phase looks to be in place over much of the nation with a broad area of high pressure in the east directing warmer than normal weather from northwest Australia into central and eastern areas of the country. Higher humidity values over the nation will support warmer nights as well. The cooler bias looks to continue over western parts of the nation with thicker cloud and the chance of further influence from the Indian Ocean. But the position of the high-pressure system over the southwest of the nation will continue to pump in onshore winds.
DATA - Refer to the video at the top of the page for further details on all this data below and to place it into context.
00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 2 Weeks
The high-pressure system that is set to develop is forecast to become the dominant force for much of the nation leading to a drier eastern and southern inland. The wettest weather will be found on the periphery of this large scale high with rain forecast to be above average over in the west of the nation with a few events on the board as mentioned and the possibility of another event developing over Central and SE QLD, chiefly near the coast with moderate to heavy falls. Elsewhere, it is looking much drier through this week which may start to shift in around a week. A strong cold front moving through WA during the early part of next week could bring a band of rain into the Bight mainly south of the mainland. Medium term shows more moisture feeding across the nation and further rainfall chances in the eastern inland of the country. This is fairly typical for this time of year as the high-pressure systems move northwards to their Wintertime location.
00Z GFS - Precipitable Water Values - Next 2 Weeks
Moisture that is feeding across the nation from northwest to southeast via the jet stream is forecast to lift northwards early this week with dry air undercutting this very anomalous moisture spread that has driven the high rainfall across the country. High pressure is forecast to dominate the synoptic elsewhere and trap the drier and cooler air that comes in from Tuesday onwards with frosty nights and fine days for the east. But all the action with the higher moisture levels will be found in the west with a large-scale system moving in from Tuesday through Thursday and yet again later in the weekend into next week. Another burst of moisture is forecast to be drawn into a trough over QLD with the better rainfall along the central and southeast coasts for now, this then spreading to the NSW coast with moderate falls developing later this week. In the medium term, the moisture should begin to spread throughout the nation with better rainfall chances moving into southern Australia towards the end of the month.
00Z GFS - Rainfall Accumulation - Next 10 Days
Refer to the video for more context and analysi
00Z GFS - Rainfall Accumulation - Next 2 Weeks
Refer to the video for more context and analysis
A closer look in - rainfall numbers will start to bounce around as we start to track some systems in the medium term, so while it is looking drier this week for most in the region, your numbers beyond about the 24th will start to change after a warmer and drier spell.
More coming up from 8pm EST with a look at the models and rainfall, where we have some interesting signals in the medium term to consider, but the broader modelling will help answer a few of my questions and hopefully some of yours as well.