CLIMATE REFRESHER - AN UPDATE TO TUESDAY'S INFORMATION

The overall pattern remains unchanged in that it is of lower confidence than usual which is normal for this time of year. This is where we see a lot of complexity enter the pattern around Australia with the fast flow pattern competing against the blocking wedges with high pressure and troughs dipping southwards from the tropics.


We have seen that in recent weeks well to the east of NZ, but one is developing this weekend into next week which is disrupting the flow of the westerly wind pattern over southern parts of the nation in the short and medium term, which in terms impacts the rainfall and temperature guide for the nation into the longer term. This is very much a feature of Winter and something that should not surprise many who like me watch the weather religiously.


So that context is important when reviewing today's data.


RAINFALL

%Chance of exceeding or not exceeding the median rainfall for the period from now through to the end of July 2022

Not a whole lot of change to the forecast guidance with the drier signal still present over parts of the southeast and interior parts of the nation but within tolerance of seasonal weather. Due to the low confidence forecast in the short and medium term, this whole forecast could be thrown out by the time we get to Tuesday, so I am not going to add too much more other than refer to the short- and medium-term forecasts and hopefully some better guidance coming up from Tuesday or next Thursday/Friday. This is typical for this time of year in the climate space where forecast confidence tends to be erratic. Also, remember that just because you may be slated in for 60% chance of seeing above average rainfall, you are a 40% chance of seeing seasonal or below seasonal rainfall. There are always two sides to the coin and sometimes the coin comes up a dud in the forecast space.

NORTHEAST AUSTRALIA AND INTERIOR

Relatively seasonal for large areas of the interior of the nation but we are looking at increasing rainfall and humidity values through the short term which may come through inland QLD or offshore to the east, we just don't know yet, but that is a signal of what is to come as we move through July and into August, leading to early onset rainfall, the end to the dry season proper and this will see rainfall increasing over the northern third of the country which is anomalous for this time of year.

SOUTHERN QLD AND NORTHERN NSW

Noting that wetter bias running through the eastern parts of QLD has not changed, but as I have mentioned above, there could be a deeper shot of moisture running through the eastern inland later next week leading to a much more widespread rain event for this entire region meaning this forecast is void after 1 week. So, stay close to the forecast packages in the short and medium term. The forecast confidence is low.

VICTORIA AND NSW

The weather is leaning drier along the southeast and southern coast of NSW and into eastern VIC and this extends back through too much of inland NSW. This is connected to the very strong negative SAM phase that the models are inputting at the moment and while it is correct potentially for this week, there is a heavy rainfall event possibly spreading in from QLD into the state which could throw this forecast out, so stay close to the forecasts in the short and medium term and come back to this forecast again on Tuesday to see the next video.

SOUTHERN AUSTRALIA

Keeping the wetter bias for the southern Agricultural Areas of SA but it is attached to the frontal weather and the signals from the negative SAM phase and the negative Indian Ocean Dipole through the period. The drier bias nosing in from NSW is connected to the negative SAM phase the models are inputting but the forecast confidence is low for inland areas as we could see a heavy rainfall event in the medium term which would throw this forecast out so as mentioned, stay close to the short- and medium-term data for more accurate forecasting.

SOUTHWEST WESTERN AUSTRALIA

Not much change from the forecast earlier in the week with the wetter bias continuing thanks to the above average SSTs offshore the southwest coast and indeed through a large section of the Indian Ocean. The coastal areas could see above average showery coverage with and following cold fronts (note how this current front performs over the coming weekend to refer to that as a base line for what we can expect through the coming 6 weeks with strong cold fronts). The seasonal rainfall values will continue for many areas away from the coast.

TEMPERATURES

%Chance of exceeding or not exceeding the median temperature for the period from now through to the end of July 2022

The forecast confidence related to rainfall and cloud coverage across the nation will have a major impact on the temperature forecast. The overall trend is for most of the nation to come through at seasonal values through the coming 6 weeks. There will be bursts of colder weather (not as long duration as we saw in early June) and there will be bursts of warmer weather developing throughout the period too (like we are seeing this weekend over the south and southeast). So, expect the weather to be volatile!


NORTHWEST QUARTER

The cooler bias over the northwest of the nation is connected to thick cloud cover, persistent moisture streaming in over the region via the jet stream (refer to the satellite today to see what is on the menu over the coming 6 weeks) and a warmer bias is likely north of this region thanks to the elevated SSTs (see below the forecast charts), with the risk of very warm weather developing with increasing humidity likely to feature from August and early onset rainfall is possible as we move into the end of the traditional dry season!

SOUTHEAST QUARTER

The seasonal values are the appropriate for the east, with the low confidence forecasts to continue. There is a warmer bias that is building over northern Australia which will begin to the displaced during the second half of July more often than not. The only thing that can cut that warmer air off at the pass is if the Indian Ocean can spit out more frequent rainfall events through that time, but at this period and as mentioned throughout the weeks, that looks to start occurring from late July into August and Spring onwards. The warmer air will likely filter into the southeast during August.

SOUTHWEST QUARTER

The cooler bias is back on the board with significant signals for widespread rainfall to impact coastal areas with a lot of cloud cover drifting in via the developing cloud bands across the Indian Ocean and then feeding into frontal weather. The frontal weather looks to maintain seasonal values, but the sea surface temperatures are playing a role in bolstering the rainfall and cloud coverage with the fronts but pumping in a lot of low cloud over the interior leading to a cooler and dimmer 6 weeks for many away from the coast.

NORTHEAST QUARTER

Noticing the warmer bias is current over the north and northeast of the nation in line with the elevated SSTs that are present throughout the northern and eastern waters. The humidity values will be on the rise and there is the chance of the some of these warmer values shifting southwards through the second half of July as we see the warmer bias building further across the north. This will be displaced if we see a broader northwest to westerly flow and start to move into inland QLD into August leading to a nice warm up.

THE WATERS SURROUNDING AUSTRALIA.

EASTERN INDIAN OCEAN

This is most certainly the engine room for a lot of woe I suspect for many of our agricultural areas in the east, with the basin warming steadily to levels not seen at this time of year since 2016. That was the year that we saw significant flooding develop in the later Winter but more so through Spring of that year for QLD, NSW and VIC. That would be on the cards again, but not one season is ever the same, and even with elevated waters and continuing strengthening warmer waters in the weeks ahead, there is some chance that the moisture can deviate and impact different areas to 2016. But a betting man would have a good chance on a nice return on the odds-on favourite outcome for widespread rainfall and flood potential developing through central and eastern areas during the coming months as this region continues to warm.

NORTHERN TROPICAL WATERS

Waters through to the north of the NT and QLD are forecast to remain elevated throughout the period which is an ongoing lag from the La Nina event of 2021/22 and the ongoing cool neutral signal throughout the ENSO. This will see elevated temperatures, humidity and the chance of elevated rainfall through the August into the Spring as we transition out of dry season and into early build up. This area will have an impact on lifting rainfall chances for the eastern parts of the country, more particularly through QLD in the spring and Summer. Cooler waters nearer the southern Gulf, normal as the winds are offshore southeast to easterly for much of this season but they will warm back up in the Spring.

CORAL SEA

Elevated SSTS throughout the Coral Sea are in response to the ongoing and lingering influence of the La Nina and developing cooler neutral phase will keep the waters nice and warm throughout the Winter and into Spring, the impacts to be felt mainly up over the northern tropics through Winter with the higher moisture values and shower activity in onshore winds. The broader impacts over these elevated temperatures will be felt through inland parts of QLD and into NSW from the Spring as the nation warms. The influence also increasing as the winds shift into the easterly wind regime.

PACIFIC AND TASMAN SEA

Cooler than normal waters developing through the Tasman Sea which is quite normal for this time of year. The weather is forecast to remain generally seasonal in response to these values. If the elevated SSTs are maintained throughout the coastal areas, then troughs or low pressure that forms over this region could deepen rapidly but only if contained to coastal areas. The overall impacts from these waters at present is minimal under the current guide. The waters are forecast to be maintained at these values through Spring.

BASS STRAIT AND SOUTHERN OCEAN

Cooler than normal waters inshore in response to the persistent southwesterly flow bringing in the colder waters from the Southern Ocean. Generally seasonal expectations from these waters are forecast to feature through the Winter with the warmer waters over northern and northwest Australia expected to be the biggest influence on moisture and that spreading throughout the jet stream and into the southeast.

GREAT AUSTRALIAN BIGHT

The inshore waters are cooler following a very persistent spell of southwest winds leading to cooler waters across the shallow waters of the southern and southeast coastal areas. Overall, the waters are where they should be for June. It is the waters to the northwest of the WA that are going to have the greatest influence on this region through the months ahead. Some modelling suggests waters over the Bight do turn above average into September and October.

SOUTHERN OCEAN AND SOUTHERN INDIAN OCEAN

Note the impacts of the persistent rainfall over the Denham region with 6C below normal! That is quite exceptional. Waters south and west of the SWLD remain elevated leading to higher moisture loads with cold fronts and onshore winds moving through this Winter. We have seen heavier rainfall vs what models have been suggesting of late as well. This will continue to persist through the coming Winter but there is a strong chance the warmer waters are moving southwards from the northern Indian Ocean, with the higher moisture levels forecast to move into the state late Winter into Spring with a protracted period of above average rainfall coming into Spring as well before the waters have less of an impact by the end of the Spring.

INDIAN OCEAN - TENDING NEGATIVE THIS MONTH AND PERSISTS TO DECEMBER.

The main influence on the nation's weather is the Indian Ocean Dipole and the negative phase is expected to be quite drawn out and deep through the latter part of the Winter into Spring with the chance of well above average rainfall spreading through the country via deep moisture in the jet stream from northern and western parts of WA and through to Central Australia, much of SA and into the southeast inland. The peak of the influence from the driver is expected from August through to November before conditions ease in December. Flooding is expected to be a significant issue as we move into Spring across large areas of the country with the highest risk expected to be located through inland QLD and NSW into northeast VIC. As we move into Summer, the IOD traditionally has less impacts on the country as we transition into the northern wet season.

SOUTHERN ANNULAR MODE - TENDING NEGATIVE FOR THE COMING FORTNIGHT.

The other main driver of greatest influence at this time of year is the Southern Annular Mode with the negative phase over the coming 2 weeks expected to fire up those westerly winds over Southern Australia leading to more cold fronts impacting the mainland, moisture being drawn in from the Indian Ocean and this seeing rainfall chances increasing as we move into the second half of June for southern WA through SA and into the southeast inland. The eastern inland could go quite dry for the next 2-3 weeks in the absence of cloud and moisture streaming in via the Indian Ocean along the jet stream. Northern Australia also looks to enjoy some drier air for the next 1-2 weeks before we see another surge of northeasterly winds moving into July. There is the chance the SAM turns back neutral during early July but then it is more likely to shift negative than positive on this current guidance (60%) during July. Negative SAM means more westerly wind dominance across the nation and increases rainfall in Winter over southern Australia but dries out the interior.

ENSO REGION - REMAINING COOL NEUTRAL WITH A REASONABLE CHANCE OF ANOTHER LA NINA DEVELOPING SUMMER 2022/23

The ENSO region is near resolving that La Nina phase with the influence waning for the nation, though noting that the elevated SSTs over northern Australia, especially north of the NT and north and east of QLD are a direct result to the prolonged La Nina and will likely remain in place through the Winter period. This may increase rainfall chances over northern and eastern Australia when upper troughs approach the region. But it is more likely that features heavily in Spring. The ENSO is likely to stay at COOL NEUTRAL for the season but there are signals that it may begin to shift back into weak LA NINA territory through Spring and into Summer increasing the chances of above average rainfall across northern and eastern Australia to the end of the year. If we see this occur, it will be working with the negative IOD, both working hand in hand to produce excessive rainfall and severe weather potential in the form of widespread flooding. With the ENSO at present, we are behind a predictability barrier that happens at this time of year, being a period of natural transition, and better guidance for this driver will become available from mid July onwards.

More weather information coming up this afternoon in a broader weather video leading into the weekend and next week, and more information on this system approaching WA today and the east from next week.


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