June 2023 outlook SA
June 2023 outlook SA
*Forecast prepared between May 31st-June 3rd 2023
Review:
G’Day everyone, I hope you are all keeping well - time for the June outlook as we approach the halfway mark of 2023 already which feels like it has come on as quick as ever, I have to say.
Now May was quite the month, a bit of yin and yang about it with a moist start, large dry middle and fairly wet finish, especially in those areas that were under streams and on windward slopes where orographic lift was the primary driver of increased precipitation.
The two main points to review from May were the expected dry period with dominant high pressure and then the frontal barrage to finish. The dry spell caused by the repeat high pressure saw the highest value of the SAM recorded since measurements began and although this was a brief spike, the overall pattern saw a positive trend held for many weeks with multiple 1030-1039hPa centres recorded and an overall above average pressure anomaly for the month. Taking Roseworthy for example, between the 10th and 18th inclusive, there was no rainfall at all recorded which for May is quite a long time. Overall, whilst this dry spell came off as expected, the total duration of it was a little shorter than I originally anticipated by about a week or so as we did take a while to get going in that regard.
After this though, we were running well below average in terms of rainfall, but thankfully the month finished with plenty of moisture as an active Long Wave Trough threw up multiple fronts around our longitude and out to about Tasmania resulting in showers, windy conditions at times and good rainfall if one wasn’t too far north. The 25th/26th saw a NW Cloudband with rain and then stream showers to follow deliver handy totals to even the Riverland with 13.6mm at Renmark and numerous other good totals of 10-20mm. Ongoing streams, especially into both the Lower and Upper North, Northern to Central YP and also the Adelaide Plains and Mt.Lofty Ranges did well here with the orographic lift giving a kick to that Southern Maritime air. Many locations managed to finish the month with 6 consecutive rain days which is also fairly impressive for May. So the net result of all of this can be summarised by looking at the anomaly charts below:
Figure 3: May 2023 rainfall anomalies – source http://www.bom.gov.au/climate/
The May outlook was as follows: “Now to the all-important May outlook and it should come as no surprise that there have been no changes to this thought process from many months ago. It will be a dry month broadly speaking, especially inland where the onshore flows will struggle to penetrate with any regularity. As a result, I see below average to well below average rainfall across the Pastoral Zones, especially however over the N and NE. General below average rainfall for Northern EP and the Upper North and right down through the Riverland and much of the Mallee. Most other areas will be slightly below average overall on windward slopes and coasts and down to the Lower SE. I cannot see any above average rainfall this month however the mostly likely location to get at least their average will be Lower Eyre Peninsula and KI.”
Broadly speaking, a reasonable effort in terms of tendency of the drier to less dry areas with the Pastorals struggling the most with well below average rainfall (even though these averages are small). The agricultural areas did fare better in the end thanks to the good finish with some getting very close to average rainfall, however most still fell just short in the slightly below average area. The Coorong region fared the best with above average rainfall as well as the general Adelaide Plain and Mt.Lofty Ranges area with just above average which was a great effort considering where it came from a week prior! Overall, though a lot of red on the deciles chart and I thought I’d expand that to the nationwide chart below to truly reflect the broad impact of the downwelling and expansion of
the Hadley cell – SA did fare better than most to be honest in this regard with SW WA coping the raw end of the deal especially so with the supressed fronts and dominant positive SAM (See Figure 4).
I should make a mention though that some portions of SW WA north of Perth but also W to NW of Esperance have got off to a cracking start to June with areas of rain, showers and isolated thunderstorms across the region on the 31st. This rainfall will go onto June’s total, and it looks like plenty more is to come down there which I will touch on in the next section.
Meteorological Discussion:
Now there is a fairly complex pattern unfolding at the time of writing this with a lot of strong jetstream activity. I’ve been tracking and re-analysing the 5 headed monster (that being the polar westerly belt with Longwave Trough nodes) and am seeing signs the 5 nodes pulling into 4 larger nodes for a short while. But the interesting thing is that the high pressure is still similar in size with large powerful highs being met with these broader longwaves. Now what this generally means is we can expect blocking and meandering of the jetstreams with longer windows or periods of where we can see fronts from the SW and in general precipitation in our part of the world.
Whilst broadly expecting below average rainfall through till at least September, I have mentioned June as the month most likely to buck that trend with some handy rainfall and certainly this appears to be shaping up for a month not void of strong dynamics with numerous systems likely, though Eastern Australia may be in the better zone due to the Tasman High channeling in some Pacific moisture from those warmer SST’s off the east coast. Typically during El Nino we see dominant westerlies in the low levels and dry conditions across the east but we must remember that the El Nino is not here yet and so whilst we have a window to get some rain in, it will be a lot easier for that moisture to have a good crack at feeding SW into QLD, NSW, VIC and even into parts of SA from the Coral Sea ahead of those approaching systems from the west and the areas of greatest convergence between the blocking high and the longwave to the west will be over VIC and NSW and potentially eastern SA as well. This impact reduces the further west one goes. I think this is probably the last month we will see it to this level before high pressure comes back and the general downwelling resumes with weaker triggers and rain bearing systems.
Currently though we have a large Tasman High directing mild to warm conditions across the state with a NE-N airstream keeping temperatures well above average for the start of June. These conditions in this NE-N airstream will persist for a number of days thanks to the high is forming a block. A weakening cut off low has developed over the Bight and has been squeezing the jetstream aloft in the last couple of days with some patchy light rain areas from time to time, chiefly over the Eyre Peninsula and Upper North and down into the Riverland and Mallee but for the most part totals have been less than 2mm given the trigger is a long way to the west and the overall depth of moisture is segmented into mutiple thin layers. Now with such blocking in the Tasman this weakening cut off won’t have anywhere to go. It cannot wander inland like some of them do but instead will be steered swiftly back down to the westerly belt which is something I like to see. Often when a cut off gets re-absorbed into the front side of a longwave, it allows for some brief Fujiwhara effect to take place causing more dumbelling of the lows around the longwave and can effectively, propel or sling systems back around the other side or trigger multiple shortwave troughs which can intensify into cold fronts etc. The Fujiwhara Effect is a term given to the process of two lows inetracting with each other and rotating around a common axis. Now this is best applied when they are of similar strength but when one is far larger or smaller this effect is reduced and the larger one generally consumes the smaller but still not without some rotational impacts or wobbling. I won’t drive you batty with the physics of it!
In any case this cut off low will drift south through the Bight slowly on the 3rd and largely dissolve on the 4th and 5th as it gets captured a large low embedded in the Longwave Trough. Further inland, a weak upper low aloft responsible for inducing this surface cut off low will also weaken but being higher up in the atmosphere will see it take a more SE path than south and thus still give some lift ahead of it as it moves into NSW. Areas of mid-level showers and an isolated thunderstorm or two (but not a lot thundery wise) will extend south across SA, tending to patchy rain areas at times north of about Port Augusta and up to the NE corner of the state, mostly later on the 4th and through the 5th in a fairly mild to warm N flow. Over in NSW at least the upper low will hit greater levels of moisture and generate heavier areas of rain and isolated thunderstorms across some rather dry
(amazing how things change from spring) areas of inland NSW and into N VIC on the 5th with repeat afternoon showers developing in the moisture leftover in NSW and VIC on the 6th as well with a near humid NE-N flow.
Now on the 4th a strong cold front will slam into SW WA as a powerful upper low develops and ‘breaks’ below SW WA (think of a wave breaking on the beach). These breaking waves are almost always associated with severe weather with isolated weak tornadoes and damaging winds likely over SW WA from this system. A second front will smash in during the 5th with heavy falls and squally winds. The entire focus for this first setup will be over WA with a slight weakening as it moves into SA. However despite the weakening, the front and assoiated upper trough will then run into that aforementioned convergence caused by the blocking Tasman hig and start to drop SE. Granted the warmth being pumped down from QLD ahead of this system combined with the moisture, I will expect the eastern and central portions in particular to be fairly unstable and spring like by winter standards on the 6th and early 7th. Scattered mid levelish showers and thunderstorms will develop late afternoon and through the evening, chiefly ahead of and along the front being lifted by the upper trough with very strong upper level divergence. These showers and thunderstorms may also contain isolated severe thunderstorms with damaging wind, intense rainfall and borderline large hail a possibility in stronger storms and will continue overnight into the pre dawn hours of the 7th. The most likely location for this activity is north and east of about Adelaide (though some will be south of too) with a focus across the NE pastoral, Upper and Lower North and Riverland and into the Mallee as well. This activity however will quickly spread to areas of rain and isolated thunderstorms, although potentilaly some locally heavy falls may occur, more likely in the east and SE of the state and less likely west of about Adelaide at this stage as due to the convective nature of this setup, there will be holes. If this front doesn’t quite stand up as high however then the intensity and spread of activity will have the edge taken off it. If the front was peaking (breaking wave) over SA, we would have a severe weather outbreak akin to weaker versions of storms in spring last year. A possible special update for this front closer to the date is likely if it still looks significant enough, just to nail down totals and any severe potential/locations.
Through the afternoon on the 7th we will see renewed convection develop along the frontal zone over the east of the state, mostly east of the ranges so showers and thunderstorms are once again likely to re-invigorate from the overnight activity as the low levels will still be warm and moist enough to allow this with upper level divergence still present.
Later on 7th as a deep low passes over waters to south of Bight, a trough will extend in from the west causing showers to develop across West and Southerrn Coasts and extend eastwards overnight into the 8th, chiefly across southern agricultural areas with isolated thunderstorms, most likely south of about Cummins to Adelaide. Through the day on the 8th the onshore flow should persist with scattered showers across the agricultural areas ahead of another cold front reaching Eyre Peninsula late evening and into Adelaide by early hours of the 9th with a band of showers.
A high will attempt to establish behind this front but likely to see more troughs or weak fronts stand up around the backside of the longwave with potential crossings on 11th to 12th with further bands of showers though timing these is well too far away at this stage but if any look significant, as usual a sep update will be issued. There may be a bit of a lull as further high pressure tries to muscle in mid-month with a weak downwelling signature revealing but I do see a return to more fronts towards the backside of the month. So to the all important June outlook and as you may imagine, it doesn’t look all that bad at all and we will see some areas get good rainfall in an out of the box month. Generally average to slightly above average rainfall for the Central parts of the state including the Lower and Upper North, increasing to above average to well above average for the eastern portions of the NE Pastoral, Riverland and Mallee. Yorke Peninsula will be around average but I think Eyre Peninsula may come just short with slightly below average, especially in the north at this stage. The NW Pastoral is likely to be mixedm with above and below average rainfall, lower towards the WA border. Kangaroo Island and the SE Districts should be close to average, but perhaps above average for the Upper SE and towards the VIC border. Western VIC will see well above average rainfall as will much of Victoria in a very wet June and some areas may even get close to 1991 levels which was very wet.
Climate Drivers
The Pacific has continued a steady movement towards an El Nino Ocean like SST structure with the continued warmth persisting off Peru but also extending in that spike along the equator. Further west across the Western Pacific, especially south of Japan, we have seen some cooling, mostly in the last 7 days. However overall, the entire basin is quite warm, especially the Coral Sea and east of PNG which tells me that moisture will still be available to feed into eastern Australia ahead of significant systems and produce rainfall for the time being, as well as East Coast Lows (ECL’s) and we are heading into that season there very soon with June often being notable for these.
Across to our west, the Indian Ocean is showing further signs of swinging over to that Positive IOD with continued warming off the Horn of Africa and to be frank almost everywhere in the Western Basin. If you draw a N-S line down from Indian right through the Indian, anywhere west of this line is getting quite warm to be perfectly honest (see Figure 5 above). The Eastern Basin is beginning to see land chill impacts across the Top End of WA/NT and QLD and this response is felt here like this because these waters are shallow and thus sensitive to warm or cold changes depending on the season. To chill things quickly like this shows the trade winds are blowing well across these areas, pulling up colder water from beneath as well as the cold land adjacent chilling from above as well. What I look for is the sustainment of this with western and northern spread and then a final development of a similar anomaly pattern off the west coast of Java and Sumatra, extending west to complete the Positive IOD. That step at least, is a fair way away yet thankfully but the current lead in steps, are classical as we move towards a moderate strength event.
The MJO has been in a moderate strength pulse through phase 7 and 8 as it moves into the America’s and Atlantic region. Interestingly, the trade winds across the Pacific have not weakened a great deal in response to that with onshore flow and warm SST’s persisting in the Coral and off PNG. Further west, the downwelling signature can be revealed over the Western Indian and this will move over us through mid-June, which will temper tropical activity for that meantime.
The SAM has been slightly positive in the last few days after briefly dipping into negative territory late May with that flurry of fronts and the broad longwave in our region, however a significant sustained negative burst in the SAM does not look all that likely just yet, but some more dips into negative territory through June can be expected.
Districts:
Eyre Peninsula
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Weakening cut off low in Bight will generate scattered showers and isolated thunderstorms over the NE to N of Eyre Pen during the afternoon and evening. Isolated showers for the remainder. Becoming fine mostly on 5th apart from an isolated afternoon shower possible. Strong upper trough and cold front extending from west late on 6th with very warm and sunny conditions ahead with temperatures in the high 20’s or even 30C inland. Scattered showers and thunderstorms developing ahead of and along the cold front from late evening and increasing into early hours of 7th especially towards the eastern portions of the Peninsula. Possible severe thunderstorms in the far NE. Shower and thunderstorm activity clearing by sunrise with a mostly fine day in the dry slot though westerly winds fresh at times ahead of an evening trough bringing showers and possible isolated thunderstorms about the West Coasts and Lower Eyre Peninsula, more isolated inland through pre-dawn hours, increasing through the afternoon with scattered showers continuing on 8th. Brief clearance again ahead of another cold front late evening with a band of showers, clearing during the 9th. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period 12-25mm, isolated totals to 30-35mm about Lower Eyre Peninsula. Totals decreasing in far N down to 7-10mm.
Upper North
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Gusty NE winds about the ranges late 3rd and early 4th. Weakening cut off low in Bight will cause scattered showers and isolated thunderstorms to develop and extend from the N during the afternoon and evening with areas of rain and isolated thunderstorms forming further N around a weak upper low. Isolated to scattered showers on 5th lingering before clearing SE later. Strong upper trough and cold front extending from west late on 6th and early 7th with very warm and sunny conditions ahead with temperatures in the high 20’s or even 30C. Isolated showers and thunderstorms developing ahead of and along the cold front from very late evening before becoming scattered and increasing into early hours of 7th with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation. Severe thunderstorms likely. Dry slot with westerly winds behind front clearing activity from lunchtime on 7th to a mostly fine day. Isolated showers developing in the south on 8th with weakening trough. Brief clearance again ahead of another cold front early hours of 9th with a band of decaying showers. Ridge likely till 11th or 12th when another front with showers is due, though for the period highly variable due to the convective nature of some precipitation however generally 12-20mm, grading to 20-30mm over the Flinders. Scattered 25-30mm falls with thunderstorms and isolated totals to 50mm with severe thunderstorms or training precipitation/localised heavy rain areas. Localised drier holes however with 7-10mm.
Lower North
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Gusty NE winds about the ranges late 3rd and early 4th. Weakening cut off low in Bight will cause scattered showers and isolated thunderstorms to develop and extend from the N during the afternoon and evening. Isolated to scattered showers on 5th lingering before clearing SE later. Strong upper trough and cold front extending from west late on 6th and early 7th with very warm and sunny conditions ahead with temperatures in the high 20’s. Isolated showers and thunderstorms developing ahead of and along the cold front from very late evening before becoming scattered and increasing into early hours of 7th with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation. Severe thunderstorms likely, especially towards the N and E. Dry slot with westerly winds behind front clearing activity from luchtime on 7th to a mostly fine day. Isolated to scattered showers developing on 8th with weakening trough. Brief clearance again ahead of another cold front early hours of 9th with a band of decaying showers. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period highly variable due to the convective nature of some precipitation however generally 15-25mm. Scattered 25-30mm falls with thunderstorms and isolated totals to 50mm with severe thunderstorms or training precipitation/localised heavy rain areas. Localised drier holes however with 10-15mm.
Yorke Peninsula
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Weakening cut off low in Bight will generate isolated to scattered showers during the afternoon and evening. Possible brief isolated thunderstorm in the N. Becoming fine mostly on 5th apart from an isolated afternoon shower or two possible. Strong upper trough and cold front extending from west late on 6th with very warm and sunny conditions ahead with temperatures in the high 20’s in the N. Scattered showers and thunderstorms developing ahead of and along the cold front from late evening and increasing into early hours of 7th. Possible severe thunderstorms in the far N. Shower and thunderstorm activity clearing by mid-morning to a mostly fine day with the dry slot, though westerly winds fresh at times ahead of an evening trough bringing showers and possible isolated thunderstorms about the foot of the Peninsula, more isolated north of here through pre-dawn hours. Showers increasing through the early afternoon of 8th once again before easing later. Brief clearance again ahead of another cold front early hours of 9th with a band of showers, with stream isolated showers in the wake of front clearing during the day. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period 12-25mm, isolated totals to 30mm about foot and in far N with any thunderstorm activity. Totals possibly decreasing towards the E coast down to 10-12mm.
Kangaroo Island
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Weakening cut off low in Bight will generate isolated to scattered showers during the evening and early hours of 5th. Possible brief isolated thunderstorm. Becoming fine mostly on 5th apart from an isolated afternoon shower or two possible but minimal likely. Strong upper trough and cold front extending from west very late on 6th with warm and sunny conditions ahead with temperatures in the low to mid 20’s. Scattered showers and isolated thunderstorms developing ahead of and along the cold front from early hours of 7th. Shower and thunderstorm activity clearing by mid-morning to a mostly fine day with the dry slot, though westerly winds fresh at times ahead of an evening trough bringing showers and isolated thunderstorms . Showers and isolated thunderstorms continuing through the 8th before easing later in afternoon. Brief clearance ahead of another cold front late evening on 8th with a band of showers, with stream isolated showers in the wake of front on 9th clearing later during the day. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period 25-40mm, isolated totals to 50mm about the western end. Totals possibly decreasing towards the E coast but still around 20-25mm.
Adelaide Plains
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Gusty NE winds about the ranges late 3rd and early 4th. Weakening cut off low in Bight will cause scattered showers and possible isolated thunderstorms to develop and extend from the N during the afternoon and evening. Isolated to scattered showers on 5th lingering before clearing SE later. Strong upper trough and cold front extending from west late on 6th and early 7th with very warm and sunny conditions ahead with temperatures in the high 20’s. Isolated showers and thunderstorms developing ahead of and along the cold front from very late evening before becoming scattered and increasing into early hours of 7th with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation, chiefly about the foothills and N of the city. Severe thunderstorms possible in the N. Dry slot with westerly winds behind front clearing activity from luchtime on 7th to a mostly fine day. Showers developing early on 8th more likely in the far south with a possible isolated thunderstorm before showers increase generally through the day before easing later. Brief clearance again ahead of another cold front early hours of 9th with a band of showers with isolated to scattered stream showers to follow, clearing later. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period highly variable due to the convective nature of some precipitation however generally 30-40mm. Scattered 45-50mm falls with thunderstorms and isolated totals to 55mm with possible severe thunderstorms or training precipitation/localised heavy rain areas as well as areas with lift into the foothills. Localised drier holes however with 15-30mm.
Mt.Lofty Ranges
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Gusty NE winds about the ranges late 3rd and early 4th. Weakening cut off low in Bight will cause scattered showers and possible isolated thunderstorms to develop and extend from the N during the afternoon and evening. Isolated to scattered showers on 5th lingering before clearing SE later. Strong upper trough and cold front extending from west late on 6th and early 7th with warm and sunny conditions ahead with temperatures in the low to mid 20’s. Isolated showers and thunderstorms developing ahead of and along the cold front from very late evening before becoming scattered and increasing into early hours of 7th with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation, more likely about the Northern ranges. Severe thunderstorms possible about the Northern Ranges also and towards the rear slopes. Dry slot with westerly winds behind front clearing activity from luchtime on 7th to a mostly fine day. Showers developing early on 8th more likely towards the Central to southern ranges about the Fleurieu with a possible isolated thunderstorm. Showers increasing generally through the day before easing later. Brief clearance again ahead of another cold front early hours of 9th with a band of showers with isolated to scattered stream showers to follow, clearing later. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period highly variable due to the convective nature of some precipitation however generally 35-45mm. Scattered 50-60mm falls with thunderstorms and isolated totals to 70mm with possible severe thunderstorms or training precipitation/localised heavy rain areas as well as higher peaks/known wet spots. Localised lower totals however with 20-35mm.
Riverland/Mallee
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Weakening cut off low in Bight will cause scattered showers and isolated thunderstorms to develop and extend from the N during the afternoon and evening. Isolated to scattered showers on 5th lingering before clearing SE later. Strong upper trough and cold front extending from west late on 6th and early 7th with very warm and sunny conditions ahead with temperatures in the high 20’s or even 30C in the N of the Riverland. Isolated showers and thunderstorms developing ahead of and along the cold front from very late evening before becoming scattered and increasing into early hours of 7th with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation. Severe thunderstorms likely, moreso over the Riverland. Renewed showers and thunderstorms developing at rear of initial band during afternoon of 7th closer to eastern border areas, with activity clearing behind this during the mid to late afternoon. Isolated showers developing in the south/SW of both districts, though mainly Mallee only on 8th with weakening trough. Strong rain shadow effect here in westerly flow. Another cold front early hours of 9th with a band of decaying showers, more isolated over the Riverland. Ridge likely till 11th or 12th when another front with showers is due, though chiefly south of the Riverland. High pressure may briefly take over again till mid-month. Rainfall for the period highly variable due to the convective nature of some precipitation however generally 18-28mm. Scattered 30-40mm falls with thunderstorms and isolated totals to 50mm with severe thunderstorms or training precipitation/localised heavy rain areas. Localised drier holes however with 7-15mm but these will be smaller with eastern extent.
Upper SE
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Weakening cut off low in Bight will cause scattered showers and isolated thunderstorms to develop and extend from the N during the afternoon and evening. Isolated to scattered showers on 5th lingering before clearing SE later. Strong upper trough and cold front extending from west late on 6th and early 7th with very warm and sunny conditions ahead with temperatures in the mid 20’s. Isolated showers and thunderstorms developing ahead of and along the cold front from early on the 7th becoming scattered and increasing from sunrise with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation. Severe thunderstorms possible in the N. Renewed showers and thunderstorms developing at rear of initial band during afternoon of 7th closer to eastern border areas, with activity clearing behind this during the mid to late afternoon. Isolated showers and a possible thunderstorm developing near the Coorong coast on 8th with weakening trough. Another cold front early hours of 9th with a band of showers with stream isolated to scattered showers to follow, before clearing later. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period highly variable due to the convective nature of some precipitation however generally 25-35mm. Scattered 35-40mm falls with thunderstorms and isolated totals to 50mm with severe thunderstorms or training precipitation/localised heavy rain areas. Localised drier holes however with 15-25mm but these will be smaller with eastern extent.
Lower SE
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Weakening cut off low in Bight will cause scattered showers and isolated thunderstorms to develop and extend from the N during the afternoon and evening. Isolated to scattered showers on 5th lingering before clearing SE later. Strong upper trough and cold front extending from west late on 6th and early 7th with warm and sunny conditions ahead with temperatures in the low to mid 20’s. Isolated showers and thunderstorms developing ahead of and along the cold front from early on the 7th becoming scattered and increasing from sunrise with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation. Renewed showers and thunderstorms developing at rear of initial band during afternoon of 7th closer to eastern border areas and chiefly to the N, with activity clearing behind this during the mid to late afternoon. Scattered showers and isolated thunderstorms developing near the coast on 8th with weakening trough. Another cold front early hours of 9th with a band of showers with stream scattered showers to follow in a colder airmass before clearing later. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period highly variable due to the convective nature of some precipitation however generally 25-35mm. Isolated totals to 40-50mm with thunderstorms or training precipitation/localised heavy rain areas. Localised drier holes however with 20-25mm.
Western VIC
Warm conditions on 4th as a strong Tasman high directs a NE-N airstream across the district. Weakening cut off low in Bight will cause isolated showers to develop and extend from the N during the afternoon and evening, mostly closer to the SA border. Isolated to scattered showers as well as light patchy rain areas on 5th before dissolving and clearing SE later. Further isolated to scattered late morning to afternoon showers on 6th with convection of lingering moisture in a humid airmass, more likely to the N and E. Strong upper trough and cold front extending from west early on 7th with warm conditions ahead with temperatures in the mid 20’s. Isolated showers and thunderstorms developing ahead of and along the cold front from early on the 7th becoming scattered and increasing from sunrise with areas of rain developing also. Localised heavy falls in thunderstorms or training areas of precipitation as well as within the rainband itself. Severe thunderstorms likely, chiefly over the Mallee District ahead of the rain areas with discrete fast moving thunderstorms. Renewed showers and thunderstorms developing at rear of initial band during afternoon of 7th closer to the SA border, with activity clearing behind this during the later evening. Isolated showers developing about the SW District generally on 8th with weakening trough. Another cold front early hours of 9th with a band of showers (more isolated and weakened over the Mallee and Wimmera) with stream isolated to scattered showers to follow, before clearing later. Ridge likely till 11th or 12th when another front with showers is due. High pressure may briefly take over again till mid-month. Rainfall for the period generally 35-45mm. Scattered 50-60mm falls with thunderstorms and isolated totals to 70mm with severe thunderstorms or training precipitation/localised heavy rain areas. Totals grading down to 25-30mm but most should see at least this for the period.
Final Notes
- Record breaking warm conditions likely on 6th with numerous all time records for June likely to fall in warm N airstream ahead of a vigourous cold front generating showers, rain , thunderstorms and localised heavy falls, especially with eastern extent
- More significant rainfall for inland NSW and VIC due to proximity of sustained Coral Sea moisture
- Very spring like event on 6th/7th with powerful upper jetstream and divergence which will generate severe thunderstorms, amply fueled by the unseasonal low level warmth
- Drier to the west without this influence but multiple fronts in this favourable Longwave Trough node will keep showers coming for coastal districts
- Return to drier conditions after June likely, more so inland with frosts
- El Nino and Positive IOD still in development, but will occur at a moderate strength
- Very warm SST’s worldwide tro be watched for impacts on 2024, potentially wet with El NIno breakdown and rebound IOD to neutral or negative
- If however El Nino crashes/fails like 2014 then we double down and go for proper in 2024 (much like 2015) but at this stage I feel that is less likely.
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Happy Farming and Cheers from The Weatherman
*Note – For interest only, all thoughts are of The Weatherman and may not be reproduced without my consent.
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