SA - SHOWERS CLEAR THE EAST, DEVELOPS OVER THE SOUTH FRIDAY. CAN WE BUY A DECENT EVENT SOON?

We are sitting in between all the weather makers at the moment, with falls of 40mm literally on the NSW border in recent days and barely a drop getting 20km west of the border, the cruel rainfall distribution for many in the state has been hard to cop. The light rainfall that has been about the far eastern border areas should continue but move into VIC and NSW tomorrow as a front approaches the western border areas tomorrow night.


This front will peak over in WA, so once again, the large and productive rain band will likely fall apart on approach to the state bringing light rainfall to southern Ag areas with the chance of a few moderate falls in the southeast where moisture could be deeper.


A cooler drier airmass will pass through the state from Saturday and while there is another front due in on Sunday, it looks weaker on current presentation, so a few showers and drizzle for the south and southeast at best before a new high moves through on Monday.


A dry start to next week with seasonal temperatures.


Watching the moisture building over the northwest and northeast of the nation yet again through the coming medium term, which could lead to better rainfall chances (we can hope!) with inland rainfall over WA likely to be above the average and further rain developing over inland QLD and NSW. While surrounded, the moisture will be moved around the nation with the chance of this moisture linking up with cold fronts or trough.


This is the reason why we are seeing the longer term modelling suggesting above average rainfall, but remember, even if you are a 70% chance of seeing above average rainfall, you are also a 30% chance of seeing seasonal rainfall or less. Being that the state sits in the swing zone where systems peak and pass, it is not uncommon for rainfall to be less than expected through May but flip in June onwards.


Let’s take a look

FORECAST

Rainfall Next 10 Days

Rainfall is forecast to be patchy and light over the east as the backside of the rain band begins to shift eastwards into NSW and VIC. The rainfall focus then shifts into the west of the state with a large cloud band moving in, but the dynamics supporting widespread rainfall of moderate falls is likely to be found back in WA. The system falling apart as it moves through the south of the state during Friday afternoon into Saturday meaning light falls of up to 5-8mm for coastal areas and the southeast is the likely outcome. 1-3mm for northern areas. The weather dries out next week with a new high but as mentioned in the video, watching that moisture building across the nation with higher-than-average rainfall forecast over inland WA with the jet stream cloud band and over northeast parts of the nation with the easterly winds propelling moisture into the north of the state by the time we get to the end of next week. Zoomed in charts to return once we get the east coast system out the door and take a look at the impacts from the WA moisture infeed this weekend for the medium term.

MEDIUM TERM - May 18th-25th 2022

Rainfall Anomalies

It appears that the rainfall signals for the east are gathering once again above the average through this period with a very high moisture content developing over the east of QLD into NSW and a trough linking into this bringing up rainfall chances once again. This may drift into VIC. Moisture through the jet stream brings up rainfall chances for the western interior. This moisture is expected to spill through the country and feed the system in the east as well with high rainfall totals likely on current guidance for inland NSW and QLD. Ag SA may sit too far south for the weather events yet again but will watch trends.

Temperature Anomalies

Temperatures in the north and east will reflect the high moisture content and remain above average overnight and during the daytime for the most part. Cooler bias continues out west under persistent cloud cover and moisture spreading through the state with areas of rainfall. The weather over northern Australia, up to 4C above normal with high humidity values is possible about the Top End and extending southwards and east into QLD and possibly northern SA and NSW.

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

More details can be found in the weather video on the daily breakdown but we can see the event in the east winding down in the coming days. We have the strong cold front in the west tomorrow, this system weakening as it moves east into SA and then the southeast. But a stronger spread of moisture then moves into the northwest of the nation next week and may combine with a strong cold front to bring another burst of rainfall through the west and then into SA and the southeast states. Meanwhile another trough over QLD and NSW could see showers and storms return from mid next week through to the following week. In the medium term, yet another wave of low pressure and moisture may combine to bring a widespread band of rain and thunderstorms throughout the interior and west and that too could spread into the southeast. More moisture spreads through northern Australia while the south is dealing with moving rainfall events from west to east.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The moisture distribution is very much following the guidance from last week and is now starting to clear east and southeast through the nation as a cold front picks up the flow pattern aloft and kicks the deep moisture over QLD and NSW off to the east and north. The next impulse of moisture that is coming over WA tonight is moving rapidly through the nation's south but weakening as it heads over SA and into the southeast. Still some rain can be expected with that feature. The next pulse of strong moisture comes in from the northwest of the nation via the jet stream next week while in the east, onshore winds will bring in moisture via easterly winds. Once again this opens the door for more rainfall events into the medium term with a deep moisture profile. As I always say, the marriage between the moisture and low pressure is key for major rainfall and where that happens remains to be seen.

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 - widespread rainfall in the coming 2 days is expected to be excessive, but the rainfall will become patchier as we go throughout the weekend and into next week and contract to the coast. More widespread rainfall is forecast to emerge mid to late next week over the southeast with moisture levels rising through SA and VIC through to inland NSW while showers continue along the coast.

More coming up from 8pm EDT with a look at the models and rainfall, I will only share information that is in reasonable agreement as too much is too confusing and I only want to share what is plausible at this time, so stay tuned for that.

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