January outlook 2024 SA

January outlook 2024 SA

*Forecast prepared between Jan 3rd-4th 2024

Review:

G’Day everyone, Happy New Year and hope that 2024 brings good health and prosperity to you all.

Looking back at December and it certainly finished 2023 with a bang with a wet and thundery month across many districts with multiple days of thunderstorms, with many severe thunderstorms. After the mid-month update the heavy rain did ease off however, the back side of the deep cut off low over the Eastern states resulted in a truly miserable Christmas Day (coldest on record for many locations) with fresh to strong southerly winds, light drizzly showers and mostly cloudy conditions. I know I certainly needed a jumper on outside most of the day. This system gave enormous rainfalls across multiple states with VIC, NSW, QLD copping the most significant weather. No doubt the standout talk was the destructive thunderstorm which mowed down a path through the Border Ranges area of SE QLD with a long path of snapped trees, foliage stripped, roofs torn off and powerlines twisted to the ground. This was caused by a derecho on a strong HP supercell thunderstorm with a majority of the damage being similar strength to what hit The Gap back in November 2008. I’d estimate the winds to be in the 160-180km/hr bracket. There would have likely also been an embedded QLCS (Quasi Linear Convective System) tornado that added some locally enhance damage, skipping up and down along the path but very hard to see.

I put a special update out for the VIC event mainly with the heavy rainfall and certainly some flooding did occur with multiple days of severe thunderstorms across the state, especially Central locations and toward the NW of Melbourne. The eastern parts also did get quite a bit as well with Gippsland seeing a much above average month rainfall wise.

Back to SA though and let's take a look back at the charts for December rainfall:

Figure 1: December 2023 rainfall deciles – source BoM http://www.bom.gov.au/climate/

Figure 2: December 2023 rainfall percentages – source BoM http://www.bom.gov.au/climate/   

Figure 3: December 2023 rainfall anomalies – source BoM http://www.bom.gov.au/climate/

“Overall, the outlook for December is above average rainfall for many agricultural areas, perhaps only the far eastern and SE Districts will be closer to average. Those that become affected by the main band from this event will see very much above average to near record rainfall for the month which is likely to be in that NE/NE Eyre Peninsula and Southern NW Pastoral region. The Mallee and Riverland should come out closer to average, but trending wetter towards the ranges. The far NE Pastoral may see slightly below average rainfall as well as the Far West. *I should note that the validity of this forecast has less weight due to being made a few days into the month*”

Now looking at the above images and the outlook we can certainly say that it was a close match, helped a little however by the later issuance of it. But the broad pattern of wetter versus drier areas matched up well and the main reason for this is the NE was now allowed moisture to pull back in so readily and was further away from the main triggers that dominated more central areas of the state. I do think however that the Northern Yorke Peninsula got a bit more than I envisaged, especially from that main multi day cut off low from Dec 9-12th where the training effect of thunderstorms was really maximised over that area. I would estimate the Bute region and surrounds must have received at least 20 thunderstorms over those few days.

Meteorological Discussion:

So now looking ahead for the month of January, a new year ahead of us and already the promise of a lot more rainfall than last year, certainly so in the greater growing season. There are essentially no dry signal flying in my face this year like we had for winter spring 2023, it essentially is the opposite.

The sun is really starting to flex its muscle with a lot of sunspot activity and strong CME’s (Coronal Mass Ejections) from a very large coronal hole and this needs to be watched. The weakening and tilting of the Earth’s magnetic field will compound this and allow a lot more solar and cosmic rays to penetrate deeper into the atmosphere than usual creating significant bursts of energy and strong weather systems with large Jetstream instability. To top it all off the lingering impacts from the Tongan Volcano are still present with a lot of that water vapour still trapped very high up in the stratosphere. Furthermore, we have the classic event of an El Nino breakdown with a likely La Nina to follow with all that heat in the oceans releasing further water vapour into the atmosphere. The Indonesian Throughfow Current will give a Negative IOD every shot as well which I will touch on again in the next section.

Currently as expected, we are presented with increasing moisture across the country, especially in the eastern half with numerous showers and thunderstorms in a broad but weak trough, and this includes SA however a bulk of the main thunderstorm activity has been confined to the NE Pastoral with only messy upper-level junk Ac/As cloud further south with mid-level showers. Some brief weak isolated thunderstorms have developed across the northern Riverland on the 4th at the time of writing this. Humid air will continue to feed into the state as the trough begins to deepen on the 5th-7th before it contracts eastwards.

At the same time, we have yet another upper low pushing in from the west. The main difference though this time is despite greater amounts of moisture feeding in, the upper low is much, much weaker than the previous 3 that we have seen with less lift, weaker wind shear and also quicker movement which is not allowing a stronger surface to upper connection. Nevertheless, we will be presented with a warm to hot and humid airmass with a trigger which will result in numerous showers and thunderstorms as well as patchy rain areas at times with some locally heavy falls in those thunderstorms as well as damaging wind gusts. To make things a little clearer I will break things down into the days of this event.

Fri 5th

The surface trough will gradually deepen with an upper low extending from the west over WA, giving rise to showers and thunderstorms in the far west of the state and through the Bight. Humid NE winds will feed the trough and combined with solar heating we should see scattered showers and thunderstorms develop, chiefly in the afternoon across much of the NW Pastoral and West Coast and Eyre Peninsula though I’d say the Lower Eyre Peninsula will see less and more isolated activity. Surface based isolated showers and thunderstorms in the afternoon, chiefly about the ranges of the Upper North and Flinders also. A likely band of severe thunderstorms with damaging wind potential should extend east across the NW Pastoral district and potentially northern Eyre Peninsula during the afternoon and evening before gradually weakening as it moves into less instability. Due to the upper-level lift being weaker and further west, sustainment of nocturnal thunderstorms is less likely with eastward progression so the central and eastern districts shouldn’t see a great deal.

Sat 6th

This will be the most humid day across most districts as moisture continues to pump into a surface trough. The upper low now begins to move into the Bight and thus the distance between the surface and upper lifting features is closer which will result in stronger and more widespread shower and thunderstorm activity. Showers and thunderstorms are first likely to be streaming SE through the Bight in an elevated manner lifted by the upper low but with solar heating, they should begin to form over land quite quickly, with the development gradually extending north and eastwards during the day with most districts seeing some activity. Severe thunderstorms are likely with damaging wind, intense rainfall the main features but further north and NW one goes, the risk for large hail also comes into the picture and this risk primarily starts from about the Lower North but also includes much of Eyre Peninsula, especially the afternoon. Pinning down such a day is tricky with the convective signature but it is likely that we will see multiple rounds of thunderstorms, forming in clusters at first before spreading to patchy/messy rain areas further south before a more organised squall line potentially extends from the west later in the day across the NW Pastoral, northern half of Eyre Peninsula and across into the areas well north of Adelaide later in the day. The southern end of the band may tend to more decayed storms and rain areas mixed in. The leading edge of this squall line poses the greatest risk for damaging winds but also intense rainfall and very frequent lightning with a likely large shelf cloud/gustfront attached. This will push east across the NW Pastoral and Flinders by early evening and potential well beyond the ranges up there before dying out once again with the lift and instability decreasing with eastern extent however the northern portion across the areas north of the Flinders may continue further towards the NE corner of the state as a long-lived squall line.

Sun 7th

The surface trough will continue to slowly deepen and extend SE during the day whilst the upper low will remain over the Bight but move steadily eastwards. Unlike the previous upper lows which have been strong enough to grind on themselves, this one will be captured by the flow and move eastwards much more quickly. 

If we had the strength of the last upper low combined with the low-level moisture of this event, the outcomes would have been quite nasty indeed.

In any case, showers and isolated thunderstorms will re-develop again early morning near Lower Eyre Peninsula as the upper low closes in. This activity will push eastwards through the morning with surface-based showers and isolated thunderstorms forming on the ranges and also quickly behind them, especially with a focus near the surface trough which should be anchored down across the Mallee by mid-afternoon. A warm to hot and humid day across most districts, but especially east of about the gulfs with that humid NE airstream which will tend NW to W behind the surface trough. Severe thunderstorms in the form of another squall line are once again likely, this time a focus over the Riverland, Mallee, Upper and possibly the Lower SE but even more so over the border into NSW and VIC where greater low level wind shear exists east of this trough to enhance organised multicell and possibly supercells. Flash flooding and damaging winds are the main threat again, but large hail is a possibility in the strongest storms. Once the upper low moves east, there may be further weaker isolated showers and thunderstorms develop during the evening east/SE of the ranges primarily and due to the cold air aloft there is a hail risk although unlikely to be large. Lapse rates though gradually become less steep as low levels cool with fresh southerlies extending throughout by the late evening and into Monday the 8th.

Now beyond this system we should see a little more stability take hold for a while but with increasing heat further over WA, extending back into SA as an upper ridge pushes down. The humid air will clear out later Monday 8th but with a strong high below the mainland, moisture is likely to remain inland over NSW/QLD and even VIC and it won’t take much for this to be pulled back down into SA to trigger more shower and thunderstorm activity but chiefly inland and over the NE Pastoral and border areas at that.

Now with the upper ridging pushing south hard to drag the heat down, that also ties in with the monsoon trough which will attempt to make an incursion mid-month as the MJO passes over the top of the continent.

Now as for an outlook for January, I do expect average to above average rainfall for most districts. The greatest chance of above average rainfall is the districts east of the border including the Upper and Lower SE, the Mallee and the Riverland and also the Far West/West Coast of the state. The greatest chance of below average rainfall is probably the Far North towards the NT where more upper ridging is likely to be present with significant heat. Most other areas will be average but leaning more towards the above average end.

Climate Drivers:

Onto the climate drivers now and you probably have noticed a lot of chatter about in the media as to where is this El Nino and where are the fire and floods. Unfortunately, the media hype train gets carried away with a stereotype of the same result every time, but every pattern is different, some are similar, but they are always different and on the odd occasion, very different. Many forget we had close to the driest August to mid-November periods in history for Australia which can be attributed to the Positive IOD primarily (always forgotten about) and then the El Nino. But despite the index peaking in December for the El Nino, other changes had already been well underway as we

worked towards a much wetter cycle and the breakdown of the Positive IOD assisted that but certainly the SAM being positive with the blocking pattern and help from the lingering effects of the Tongan eruption which causes the polar vortex to shrink and pull the westerlies closer allowing more easterlies to dominate across Australia.

The Pacific though is still warm right across the equatorial portions of basin and by the book we are still in an El Nino in the oceans however the atmospheric influence now is severely weakened as the tide turns the other way. The South Pacific cooling is still persistent though not as strong as 2 weeks ago. The Humboldt Current will be my main watch in the coming months to see how much cold water can begin upwelling. Essentially the turning of that tide is coming at the expected time frame with a broader warmer ocean surrounding the continent. La Nina should then develop throughout the year.

Figure 4: Current SST anomalies – source Tropical Tidbits https://www.tropicaltidbits.com/analysis/ocean/cdas-sflux_ssta_global_1.png

The Indian continues to warm as the ex-Positive IOD event vanishes rapidly. WA has been very hot and dry for the most part whilst the east has had a lot of rain, but high based thunderstorms have still been occurring with fires started from lightning. The Indian influence should begin to show its hand a bit more into WA through later Jan or Feb, especially the northern half with moisture then feeding inland and certainly as we push towards autumn, that will be a focus. For the remainder though, the basin remains warm and becomes an increasing source of tropical moisture for the rest of summer and infact for much of the year. I expect a negative IOD to develop, probably around moderate strength at this stage.

The MJO is currently re-gathering itself over the Western Indian in phase 2 and will steadily advance eastwards at a weak to moderate strength over the next few weeks timing itself for a pass across the top of Australia through mid-Jan as per the last update. It could trigger a weak monsoon, but I do not expect this to last long – we simply don’t have the Siberian High of the magnitude required to generate the essential cross-equatorial flow. Despite the lack of monsoon, there is no shortage of moisture across Northern and certainly Eastern Australia which again can be attributed to the next index.

The SAM is ruling the roost and has been the king since late November in our neck of the woods. A dominant easterly regime has allowed moisture to pour into the mainland from both the east and NE with minimal pushback. Upper troughs connected to the westerly belt continue to be blocked upstream causing the top ends to pinch off and allow upper lows to roll up and wander about. This naturally enhances the surface troughing and once the surface troughs have formed, the moisture then follows as the air is rising so naturally it needs to be pulled horizontally to replace that and when the direction is mostly E or NE, the moisture is in great abundance. I expect the current positive SAM to continue for much of summer with only very brief dips to neutral, chiefly when the MJO moves to phase 6-7.

Districts:

Eyre Peninsula

Surface trough generating isolated afternoon showers and thunderstorms as well as evening thunderstorms extending from the west from an upper low on 5th. Thunderstorms weakening to patchy rain areas during the evening. Hot and becoming increasingly humid across the district. Humid with showers and thunderstorms developing early on 6th about Lower Eyre Peninsula before developing across most other districts throughout the afternoon. Severe thunderstorms with local heavy falls and damaging winds likely, chiefly towards N and NE Eyre Peninsula late afternoon and early evening. Remaining humid on 7th with upper low causing early showers and thunderstorms to re-develop once again, chiefly over the Lower Eyre Peninsula where severe thunderstorms are possible. Showers and more isolated thunderstorms further W and N from here throughout the remainder of the day. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although still remaining humid. Isolated to scattered showers or drizzle areas at times in this flow, chiefly about the Spencer Gulf coasts. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast and hot inland. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 10-20mm, increasing to 20-30mm about the Lower Eyre Peninsula and also parts of the far NE of the Peninsula. Totals decreasing to the west perhaps 7-10mm. Localised heavy falls in thunderstorms to 50mm possible.

Upper North

Surface trough generating isolated afternoon and early evening showers and thunderstorms on 5th. Thunderstorms weakening by late evening and clearing to the east. Hot and becoming increasingly humid across the district. Humid with showers and thunderstorms developing late morning or early afternoon on 6th and continuing throughout the day. Severe thunderstorms with local heavy falls and damaging winds likely, chiefly towards N half of the district late afternoon and early evening. Remaining humid on 7th with upper low causing early showers and thunderstorms to re-develop once again, chiefly over the ranges and eastern half of the district where severe thunderstorms are possible. Showers and more isolated thunderstorms further W and S from here throughout the remainder of the day. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid. Isolated showers or drizzle areas at times in this flow, chiefly about elevated terrain. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and hot inland to the N. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 15-25mm, increasing to 25-35mm towards the Southern Flinders Ranges. Totals decreasing to the far N Flinders and also the SW down to 10-15mm although highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms to 60mm possible.

Lower North

Surface trough generating isolated afternoon and early evening showers and thunderstorms on 5th, chiefly in the west and north. Thunderstorms weakening by late evening and clearing to the east. Hot and becoming increasingly humid across the district. Humid with showers and isolated thunderstorms developing mid to late morning or early afternoon on 6th and continuing throughout the day. Severe thunderstorms with local heavy falls and damaging winds possible, chiefly towards N half of the district late afternoon and early evening. Patchy rain areas in decayed storm areas further south later. Remaining humid on 7th with upper low causing early showers and thunderstorms to re-develop once again, chiefly over the ranges and eastern half of the district where severe thunderstorms are possible. Showers and more isolated thunderstorms further W and S from here throughout the remainder of the day. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid. Isolated showers or drizzle areas at times in this flow, chiefly about elevated terrain. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and warm to hot in the N. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 12-22mm, increasing to 20-30mm towards the north of the district. Totals decreasing to the SW down to 10-15mm although highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms to 50mm possible.

Yorke Peninsula

Surface trough generating isolated afternoon showers and thunderstorms in the north on 5th. Hot and becoming increasingly humid across the district. Light patchy rain areas extending from the NW during the late evening. Humid with showers and isolated thunderstorms developing early on 6th about the foot before developing across the remainder of the Peninsula throughout the afternoon. Severe thunderstorms with local heavy falls and damaging winds possible, chiefly towards the far N of the Peninsula later in the afternoon and evening. Remaining humid on 7th with upper low causing early showers and thunderstorms to re-develop once again, chiefly over the foot again at first. Showers and more isolated thunderstorms further N from here throughout the remainder of the day, thought clearing later. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although still remaining humid. Isolated to scattered showers or drizzle areas at times in this flow. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast and hot inland. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 12-22mm, increasing to 20-30mm about the foot and also parts of the far N of the Peninsula. Localised lower totals through the central portions down to 8-12mm. Localised totals in thunderstorms to 40mm possible.

Kangaroo Island

Surface trough deepening across the state with increasing high cloud later. Possible late evening patchy light rain extending from the NW. Warm to hot and becoming increasingly humid across the island. Humid with showers and isolated thunderstorms developing early on 6th before gradually clearing during the afternoon. Severe thunderstorms with local heavy falls and damaging winds possible. Remaining humid on 7th with upper low causing early showers and thunderstorms to re-develop once again. Showers and more isolated thunderstorms further throughout the remainder of the day, thought clearing later in the evening. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although still remaining humid. Isolated to scattered showers or drizzle areas at times in this flow. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast and hot inland. Upper ridge deepening towards mid-month with potential for warm to hot conditions. Rainfall for period 15-25mm, increasing to 20-30mm in local pockets. Localised lower totals through the far eastern end down to 12-15mm. Localised totals in thunderstorms to 40mm possible.

Adelaide Plains

Surface trough generating isolated afternoon showers about the outer N plains. Hot and becoming increasingly humid across the district. Humid with showers and isolated thunderstorms developing mid to late morning or early afternoon on 6th and continuing throughout most of the afternoon before tending to patchy rain areas and clearing later. Remaining humid on 7th with upper low causing early showers and isolated thunderstorms to re-develop once again. Showers and more isolated thunderstorms then lingering throughout the remainder of the day easing later. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid. Isolated showers or drizzle areas at times in this flow, chiefly about foothills and southern suburbs. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and warm to hot in the N. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 15-25mm, increasing to 20-35mm towards the north of the district as well as potentially the far southern suburbs. Totals decreasing towards the western suburbs down to 10-15mm although highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms to 50mm possible.

Mt.Lofty Ranges

Surface trough generating afternoon convection in the north but remaining most dry. Hot and becoming increasingly humid across the district. Humid with showers and isolated thunderstorms developing mid to late morning or early afternoon on 6th and continuing throughout most of the afternoon before tending to patchy rain areas and clearing later. Remaining humid on 7th with upper low causing early showers and isolated thunderstorms to re-develop once again and become scattered towards the back of the ranges. Showers and more isolated thunderstorms then lingering throughout the remainder of the day easing later. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid. Isolated to scattered stream showers or drizzle areas at times in this flow, chiefly about southern coasts and windwards slopes as well as the higher peaks. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and warm to hot in the N. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 20-35mm, increasing to 35-45mm about known wet spots, the far outer N ranges and also the southern Fleurieu. Localised totals down to 15-20mm although highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms to 50mm possible.

Riverland/Mallee

Surface trough generating isolated afternoon showers in far N on 5th. Hot and becoming increasingly humid across the district. Humid with showers and thunderstorms developing late morning or early afternoon on 6th and continuing throughout the day. Severe thunderstorms with local heavy falls and damaging winds possible, chiefly late afternoon and early evening and chiefly about the Riverland. Remaining humid on 7th with upper low causing early showers and thunderstorms to re-develop once again chiefly towards the west at first and also the Mallee before extending eastwards during the early afternoon. Severe thunderstorms possibly in the form of a squall line with damaging winds, flash flooding and large hailstones are likely, especially towards the eastern half of both districts. Showers and isolated thunderstorms will then re-develop to the clearer air further west and later in the afternoon and evening. Severe thunderstorms are less likely than earlier although still possible. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid with perhaps some lingering pre-dawn isolated showers and thunderstorms in the far east near the border. Isolated showers or drizzle areas at times in this flow, chiefly towards the back side of the ranges. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and hot inland to the N. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 25-35mm, with localised pockets to 40mm, most likely near the border. Totals decreasing to the far W of the Mallee and Riverland and also the SW down to 10-25mm although highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms of 70-80mm possible.

Upper SE

Surface trough generating increasingly cloudy conditions on 5th but remaining dry. Hot and becoming increasingly humid across the district. Humid with showers and isolated thunderstorms developing late morning or early afternoon on 6th before tending to areas of rain and isolated embedded thunder later. Severe thunderstorms with local heavy falls and damaging winds possible, chiefly afternoon towards the Mallee. Remaining humid on 7th with upper low causing early showers and thunderstorms to re-develop once again chiefly towards the west at first and also the eastern border areas near VIC before all joining throughout the afternoon. Severe thunderstorms with damaging winds, flash flooding and large hailstones are possible, especially towards the eastern half of the district. Showers and isolated thunderstorms will then re-develop to the clearer air further west and later in the afternoon and evening and persist till the early hours of the 8th. Severe thunderstorms are less likely than earlier although still possible. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid with perhaps some lingering pre-dawn isolated showers and thunderstorms in the far east near the border. Isolated showers or drizzle areas at times in this flow. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and hot inland to the N. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 25-35mm, with localised pockets to 40mm, most likely near the border. Totals decreasing to the far W of the district and also the SW down to 10-25mm although highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms of 60-70mm possible.

Lower SE

Surface trough generating increasingly cloudy conditions on 5th but remaining dry. Hot and becoming increasingly humid across the district. Humid with showers and isolated thunderstorms developing late morning or early afternoon on 6th before tending to areas of patchy rain later. Remaining humid on 7th with upper low causing early showers and isolated thunderstorms to re-develop once again chiefly towards the west at first and also the eastern border areas near VIC before all joining throughout the afternoon. Severe thunderstorms with damaging winds, flash flooding are possible though less likely than the Upper SE. Showers and isolated thunderstorms will then re-develop to the clearer air and later in the afternoon and evening and persist till the early hours of the 8th. Severe thunderstorms are less likely than earlier although still slightly possible. Trough moves east on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid with perhaps some lingering pre-dawn isolated showers and thunderstorms in the far east near the border. Isolated showers or drizzle areas at times in this flow. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and warm to hot inland to the N. Upper ridge deepening towards mid-month with potential for hot conditions. Rainfall for period 20-30mm, with localised pockets to 40mm, most likely near the border. Totals decreasing in the far SW down to 10-20mm although highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms of 40mm possible.

Western VIC

Surface trough generating increasingly cloudy conditions on 5th but remaining dry. Warm to hot and becoming increasingly humid across the district. Humid with showers and isolated thunderstorms developing early afternoon on 6th before tending to areas of rain and isolated embedded thunder later. Remaining humid on 7th with upper low causing early showers and isolated thunderstorms to re-develop once again before becoming scattered during the afternoon. Severe thunderstorms with damaging winds, flash flooding and large hailstones are possible, especially towards the Wimmera and Mallee Districts in the form of a possible squall line before tending to rain behind the line. Showers and isolated thunderstorms will then re-develop to the clearer air further west and later in the afternoon and evening and persist through the 8th, with further re-development during the afternoon with solar heating. Trough moves east later on 8th allowing cooler moderate to fresh S winds to establish throughout although remaining humid. Isolated showers or drizzle areas at times in this flow. New ridges establishing below state from 9th-15th with warm conditions, though milder on coast/south and hot inland to the N. Upper ridge deepening towards mid-month with potential for hot to very hot conditions. Rainfall for period 25-35mm, with localised pockets to 40-45mm. Other locally drier pockets down to around 15-20mm but few and far between and highly variable due to the convective nature of the rainfall. Localised heavy falls in thunderstorms of 60-70mm possible.

Final Notes

• Complex broad trough system for coming days with showers, thunderstorms (some severe) and areas of patchy rain at times in a humid airmass with dewpoints near 20C however system lacks true focus with some messy activity at times
• Weaker upper low than previous ones suggesting this blocking pattern is gradually beginning to lose steam
• Upper ridging with heat to NW will make a move mid to late Jan with a weak monsoon incursion across the Top End
• Warm seas around mainland will build moisture into all states, including WA by end of the month
• Wetter 2024 for all districts with strong head start on previous years with saturated catchments and soils across the Murray Darling Basin. If combined with La Nina and Negative IOD, expect major flooding later in the year once again and possibly even some minor to moderate flooding by the end of summer/early autumn with El Nino breakdown

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Happy Farming and Cheers from The Weatherman

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