June 2022 outlook SA

June 2022 outlook SA

*Forecast prepared between June 2nd-4th

Review:

Wet, wet wet! That certainly was the order of the last few days across a wide array of districts.

I trust you are all well and thrilled with that opening rain, the best in a long time and importantly, getting into areas that really needed it with some truly tremendous totals coming out of known dry areas in the Mallee/Murraylands, Riverland and also Lower and Upper North. I’ll post a few noteable totals a little further below.

Firstly, though a recap of how we have gone since the last mid-month update, and it largely went as expected with the big high-pressure system setting us up with the strong easterlies meeting the significant upper troughing and NW cloudband activity from the NW which finished with a series of fronts and one very significant cut off low delivering excellent rain at the very end of the month. No doubt that cut off low was the main talking point on the 29-30th though before this came a sliding smaller trough and low giving some useful totals to load the moisture before the next system with handy 5-15mm totals occurring through many districts, including the Mallee once again.

Then the main event which I covered in the Special Update and looking back, it went very close to expectations but probably exceeded it in terms of rainfall for most districts, especially over the northern Adelaide Plains and into the NW Riverland where a powerful convergence spoke off the main low delivered a band of heavy convective showers tending to solid heavy rain areas, it was quite a sight to behold on the radar to see just how easily it penetrated over the ranges and held form. This comes back to the negative tilt which I discussed in the update – it was no ordinary system.

Noteable rainfall totals for the week ending 9am today (thurs 2nd) are as follows:

Ashton 111mm, Mt.Lofty 95mm, Crafers West 90mm, Golden Grove 86mm, Truro 80mm (this is huge for here), Salisbury 76mm, Edinburgh 70mm, Tanunda 70mm, Mintaro 64mm, Maitland 62mm, Warooka 60mm, Auburn 60mm, Jamestown 59mm, Roseworthy 58mm, Eudunda 54mm, Melrose 51mm, Streaky Bay 48mm, Blinman 46mm, Yardea 44mm, Kingscote 43mm, Alawoona 40mm, Pinnaroo 39mm, Paruna 38mm, Blanchetown 38mm, Sedan 35mm (locally higher), Renmark 32mm, Loxton 31mm and Keith 30mm.

A quick look back at the May as a whole as it certainly was a tricky month. After 90% of the month was done, most districts were looking at below average rainfall with some well below average. The big flurry at the end causes a huge shift in that with some more central districts getting average to slightly above average rainfall. There still were large a few large patches of slightly below, the deciles chart doesn’t show this as well in Figure 1 but the anomalies in Figure 2 show how varied the month ended up being with patches of above and below scattered across the state but overall, as a trend it was slightly below to average for a large area. The very much above average spot over the northern plains is courtesy of that intense wrap around band which also delivered a tornado through Salisbury South and East, 1km from my parents place, a close call indeed! The tornado was forecast however, given the risk was real though ususually these occur without anyone noticing but certainly it is easy to notice when it mows a path through the suburbs, and I wish all those affected well.

The May outlook for interest is as follows: “Overall, my early outlook for May is average to below average rainfall for the most part, however, some near average to barely above average conditions may present themselves across the NE Pastoral from inland feeds and also portions of the Far West Coast, KI and Lower SE, especially later in the month.”

Overall, I’ll give that a pass, certainly missed the bullseye through the northern plains and into the Mallee but the rest not too bad.

Meteorological Discussion:

Now onto the current proceedings and it will come as no surprise that plenty more rainfall is expected as we undergo a secondary barrage of fronts and cold air into the state, similar to the last event but not as high end or severe and with less assistance from the jetstream so overall dynamics will be less significant. Nevertheless, the fronts and cold air will be relentless during the period Sat 4th to Mon 6th with a more southerly flow after that as a very stretched N-S high pressure ‘digs’ in to the south and angles cold onshore flow with more small-scale troughs and light drizzly showers, thicker at times about more southern onshore slopes and ranges.

So, timeline we will see an increase in showers in a moist WNW flow across more southern portions of the agricultural area through Saturday in the wake of a trough on Friday 3rd. Areas especially south of about Cummins to Maitland to Adelaide to Bordertown will see more frequent shower activity than areas further north, especially at first during Saturday 4th however as the day wears on this activity will extend more northwards as well.

Whilst this is happening, a strong cold front will be undergoing a process called frontogenesis where the front is being born out of an older cold pool. The further north it goes, the greater the temperature gradient before and after the boundary will be and hence the front will strengthen, all the way into the coastline and smack hard into the state overnight on the 4th with the leading edge due into KI around 7:30pm local and Adelaide approx 10”30pm local. The front will cause showers to increase ahead of it as it closes in with some local heavy falls developing, especially about the Mt.Lofty Ranges. With the front itself, showers will thicken and possibly tend to rain at times about the ranges with some heavy activity causing rapid stream rises, it will be a very wet night into the early hours of Sunday the 5th. Winds will be strongest ahead of the front as the isobars squeeze from the NW but also be gusty at times still especially with any stronger cores of rainfall and linear lines along the front. The tornado risk is smaller than the last event but is still a small chance at least, especially ahead of the front tonight and on the front itself as low-level shear shows some small turning.

Behind the front, cold and blustery conditions will set in ahead of a secondary trough marked by a large pool of cold air which will barrel in with squally showers, isolated thunder and small hail, especially more likely south of about Clare. The most unstable air will be during the afternoon of Sunday 5th and this air will be more unstable than along the front itself but another wet day. Further behind for Monday 6th we have another trough embedded in the cold air due from the SW followed by yet another trough rotating up more from the south in early hours of tues 7th.

Beyond this we will see showers gradually thin out and become more isolated and eventually clear by around 10-11th of June, quite a long time away so most days, especially over elevated terrain and exposed coasts and ranges or adjacent to coasts will set precipitation most days until then so the totals will tick over.

Once the new ridge moves in, it will slowly weaken over a few days, and this is where the first main frost risk of the year comes in so from about 11th to 15th at this stage so, please be ready for some back to back cold nights though the extreme cold from the drier years looks unlikely at this early stage. Most of these should be in the light to moderate range.

Overall, June is likely to be an average to above average month for many districts. The greatest chances of above average rainfall is in the Central regions of the state including Adelaide, Mt. Lofty Ranges and down into the SE Districts and possibly also the southern Mallee. The greatest chance of not meeting average may be in the northern portions of the upper North and in the far West.

Winter as a whole is still looking good, no changes from the average to above average forecast with potential for much above average in many districts once we get into early spring and this increases the chances of large water sheeting, flooding and the likes as the catchments and soils become more saturated. I will be extremely surprised if we don’t have moderate to major flooding issues in known flood prone areas, especially the Gawler River, Mt.Lofty Ranges, by Sep-Oct. Spring should gradually taper off but is also likely to come in at least near average but likely above.

Climate Drivers

Now the all important Pacific has been driving moisture from above average trades into Australia all year and this still hasn’t changed. However, there is finally a sign that the La Nina will be facing its biggest challenge yet with an eastwards advance of the warmer sub-surface in the western Pacific. The East is still pumping out the colder anomalies thanks to an active Humboldt Current. I expect a good battle here with a diluting of the colder east and an overall weakening over the coming month or so to a cool neutral but no further.

Now the Indian has begun to take control, the NW cloudbands have been streaming in every few days with some linking up to frontal systems and cut offs lows (like the big event end of May) whilst others are steadily streaming SE across the interior but still delivering rain and this is important. Wetting the interior just increases moisture reserves in the soil and assists in giving later season fronts and troughs a pre-frontal wind that is not moisture sapping as it usually is but moisture giving. The current SST anomalies can be found below in Figure 4:

Overall, the warmth has returned even greater across the N portions of the mainland after a brief cooling last week under a big cloudband. The cooler anomalies off the NE portions of Africa remain which is a good sign for a circulation with upwelling showing westerly winds blowing offshore there.

The MJO has continued to push eastwards this time with a much more significant push out to phase 7 and nearly 8 which has also co-incided with that warmer anomaly creeping eastwards in the sub-surface. It will be interesting to see how the remainder of the Pacific SST structure responds to this. I expect the MJO to come around back to the Indian in a week or two but at a weaker rate.

The SAM has recently enjoyed a little swing to negatives values though it still fits within a neutral range. The solid front burst and expansion of the polar vortex has allowed this but after this next flurry of fronts where we will dip back to a lower negative value, the index is likely to rise back above 0 towards 1 and more positive values as we set up with a large high-pressure system.

Districts:

Eyre Peninsula

Showers increasing later on 4th as a strong cold front approaches. Showers may be heavy at times about the western coast of EP and also Lower EP during the evening closer to the frontal passage which is due around 8-830pm local. Isolated thunderstorms possible about the tip of Lower EP. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely again about Lower EP. Activity more isolated over the NE EP where some shadowing will occur. Scattered showers then becoming more isolated later 5th before increasing again on 6th with trough and secondary pool of cold air. A third trough with more southerly angle due early on 7th with another increase in showers, again more over the Lower EP, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight frost risk from 11th-15th. Rainfall for period 15-25mm, with scattered totals to 30mm about the SW coastline of Lower EP. Isolated potential locally higher totals to 40mm in a similar region. A decrease towards the NE corner of EP with totals here down to 5-10mm for the most part.

Upper North

Showers increasing early on 5th as a strong cold front approaches. Showers may be heavy at times about the higher terrain closer to the frontal passage which is due around 7-8am local. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the far south and more isolated north of about Hawker. Activity more isolated over backs of ranges where some shadowing will occur. Scattered showers then becoming more isolated later 5th before increasing again on 6th with trough and secondary pool of cold air. A third trough with more southerly angle due on 7th with another increase in showers, again more over elevated terrain, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight to moderate frost risk from 11th-15th. Rainfall for period 18-30mm, with scattered totals to 35mm about elevated terrain. Isolated potential locally higher totals to 50mm about Melrose etc and where any streams potential setup. A decrease towards the backs of the ranges and far NE of the district with totals here down to 5-8mm for the most part.

Lower North

Showers increasing late 4th and early 5th as a strong cold front approaches. Showers may be heavy at times about the higher terrain closer to the frontal passage which is due around 2:30-3am local. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the south. Activity more isolated over backs of ranges where some shadowing will occur. Scattered showers then becoming more isolated later 5th before increasing again on 6th with trough and secondary pool of cold air. A third trough with more southerly angle due on 7th with another increase in showers, again more over elevated terrain, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight to moderate frost risk from 11th-15th. Rainfall for period 20-35mm, with scattered totals to 40mm about elevated terrain. Isolated potential locally higher totals to 60mm and where any streams potential setup. A decrease towards the backs of the ranges and far NE of the district with totals here down to 8-15mm for the most part.

Yorke Peninsula

Showers increasing late 4th and early 5th as a strong cold front approaches. Showers may be heavy at times closer to the frontal passage which is due around 9-930pm local. Isolated thunderstorms possible ahead of and near front about the foot of YP. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the south. Scattered showers then becoming more isolated later 5th before increasing again on 6th with trough and secondary pool of cold air. Isolated cold air thunder and small hail is once again possible, especially in the south. A third trough with more southerly angle due on 7th with another increase in showers, again chiefly in the south, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight frost risk in north from 11th-15th. Rainfall for period 18-30mm, with scattered totals to 40mm. Isolated potential locally higher totals to 45mm and where any streams potential setup. A decrease towards the E coast possibly with totals here down to 15-18mm for the most part.

Kangaroo Island

Showers increasing late 4th and early 5th as a strong cold front approaches. Showers may be heavy at times closer to the frontal passage which is due around 8:30-9-pm local. Isolated thunderstorms possible ahead of and near front. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the south. Scattered showers then becoming more isolated later 5th before increasing again on 6th with trough and secondary pool of cold air. Isolated cold air thunder and small hail is once again possible. A third trough with more southerly angle due on 7th with another increase in showers, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight frost risk in centre of island from 12th-15th. Rainfall for period 20-30mm, with scattered totals to 40mm. Isolated potential locally higher totals to 50mm about the West Coast. A decrease towards the E coast possibly with totals here down to 15-20mm for the most part.

Adelaide Plains

Showers increasing late 4th and early 5th as a strong cold front approaches. Showers may be heavy at times closer to the frontal passage which is due around 11:00-pm local. Isolated thunderstorms possible ahead of and near front, chiefly about southern ranges. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail. Scattered showers then becoming more isolated later 5th before increasing again on 6th with trough and secondary pool of cold air. Isolated cold air thunder and small hail is once again possible. A third trough with more southerly angle due on 7th with another increase in showers, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow, especially about foothills before large high gradually muscles in after 10th. Slight frost risk about northern plains from 11th-15th. Rainfall for period 25-40mm, with scattered totals to 45-50mm. Isolated potential locally higher totals to 50-60mm and where any streams potential setup. A decrease towards the outer NE plains and W suburbs of Adelaide down to possibly 18-25mm though I’d consider a centre unlucky to be under 20mm.

Mt.Lofty Ranges

Showers increasing late 4th and early 5th as a strong cold front approaches. Showers will be heavy at times closer to the frontal passage which is due around 11:30pm local. Moderate stream rises and brief flooding are possible. Isolated thunderstorms possible ahead of and near front, chiefly about southern suburbs and beyond. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail. Scattered showers then becoming more isolated later 5th before increasing again on 6th with trough and secondary pool of cold air. Isolated cold air thunder and small hail is once again possible. A third trough with more southerly angle due on 7th with another increase in showers, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow, especially about higher terrain and exposed coasts and ranges before large high gradually muscles in after 10th. Slight frost risk about low lying valleys from 11th-15th Rainfall for period 30-50mm, with scattered totals to 60-70mm. Isolated potential locally higher totals to 100mm, more likely about those known wet spots where showers are likely to turn to rain with maximum orographic lift. A decrease towards the far north of the Lofties but still quite solid in the order of 25-35mm.

Riverland/Mallee

Isolated showers about eastern slopes of ranges increasing early on 5th as a strong cold front approaches. Showers may be heavy at times closer to the frontal passage which is due around midnight over the southern Mallee, before a slow progression NE towards the Riverland. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the far south of the Mallee and less likely over the Riverland. Scattered showers then becoming more isolated early 6th before increasing again on 6th with trough and secondary pool of cold air. A third trough with more southerly angle due on 7th with another increase in showers, again more over elevated terrain, becoming isolated later. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight to moderate frost risk from 11th-15th. Rainfall for period 15-25mm over the southern half of the Mallee, with scatt streams set up, more likely in S/SW. A marked decrease this time towards the Riverland with totals down in the 5-8mm range.

Upper SE

Showers increasing late 4th and early 5th as a strong cold front approaches. Showers may be heavy at times closer to the frontal passage which is due around 11:00pm local. Isolated thunderstorms possible ahead of and near front. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the south. Scattered showers then becoming more isolated early 6th before increasing again during the morning with trough and secondary pool of cold air. Isolated cold air thunder and small hail is once again likely. A third trough with more southerly angle due late on 6th with another increase in showers, becoming isolated later on 7th. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight to moderate frost risk from 12th-15th. Rainfall for period 20-30mm, with scattered totals to 40mm. Isolated potential locally higher totals to 50mm in far south. A decrease towards the far NE of the district but still good falls to near 20mm.

Lower SE

Showers increasing late 4th and early 5th as a strong cold front approaches. Showers may be heavy at times closer to the frontal passage which is due around 09:00-9:30pm local. Isolated thunderstorms possible ahead of and near front. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the south. Scattered showers then becoming more isolated early 6th before increasing again during the morning with trough and secondary pool of cold air. Isolated cold air thunder and small hail is once again likely. A third trough with more southerly angle due again late 6th with another increase in showers including a possible cold air thunderstorm before becoming isolated later on 7th. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight to moderate frost risk from 12th-15th. Rainfall for period 25-40mm, with scattered totals to 50mm. Isolated potential locally higher totals to 60mm in far south. A decrease towards the far NE of the district but still good falls to near 25mm.

Western VIC

Showers increasing late 4th in the far SW and early 5th further north as a strong cold front approaches. Showers may be heavy at times closer to the frontal passage which is due around 11:00pm local in the SW, and into the early hours further north towards the Mallee district where the front will slow down. Isolated thunderstorms possible ahead of and near front, especially so about the coast. Strong and gusty NW winds ahead of the front turning colder W-SW behind the front. Cold pool with trough on 5th behind front with squally showers, isolated thunder and small hail, more likely in the SW. Scattered showers then becoming more isolated early 6th before increasing again during the morning with trough and secondary pool of cold air. Isolated cold air thunder and small hail is once again likely. A third trough with more southerly angle due again late 6th with another increase in showers including a possible cold air thunderstorm before becoming isolated later on 7th. Lingering onshore flow will keep isolated showers and drizzle patches at times in cool to cold southerly flow before large high gradually muscles in after 10th. Slight to moderate frost risk from 12th-16th. Rainfall for period 25-40mm over the SW District, with scattered totals to 50mm. Isolated potential locally higher totals to 60mm in far south. A decrease towards the north with 15-25mm over the Wimmera and 5-15mm over the Mallee, the 15mm closer to the southern border.

Finals Notes:

• · Wet start to June before a reprieve from the rain though in this period the frost risk increases
• · La Nina starting to show signs that is might finally weaken to a cool neutral state but at same time Negative IOD is increasing in strength
• · Watching for another strong infeed from the NW towards end of month or early July as wet set up once again
• · Big snowfalls in Alpine regions, could be one of best starts in a long time which will contribute to higher spring melt and Murray inflows (which are already good)
• · Expecting spring to summer Murray River flooding in low lying areas, something to watch out for

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Happy Farming and Cheers from The Weatherman

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