The end of July is moving into the medium range forecasting which I have covered off in greater details in recent days and will again later this morning.
So what does August 2022 look like? There are many sweating on rainfall coming back and the seasonal expectations are based off the Climate Drivers that we should see a marked increase in rainfall but also temperatures over northern Australia.
The Indian Ocean is in the process of cooking away as what is expected at this time of year and that will lead to more robust moisture plumes coming through the jet stream. I will cover that off in further information during the weekend as to the general impacts of the moisture from the Indian Ocean from month to month.
The warmer waters offshore the east coast of QLD are somewhat anomalous and are continuing to increase in temperature as the persistent cooler waters over the ENSO remain stubborn and likely to sit there through the remainder of Winter 2022.
With the SAM tending negative as we track into the end of this month and into early August, we may see quite active frontal weather passing through from west to east and the moisture may be drawn into the southern and southeast states leading to more widespread falls than what we have seen.
FORECAST VIDEO - AUGUST 2022 - ISSUED JULY 15TH 2022 11AM EST.
CHARTS AND NOTES
Rainfall Outlook August 2022 (White Zones are areas that are forecast to be at a higher chance of seeing seasonal values with numbers scaling up and down from that point leaning wetter or drier)
Rainfall is expected to increase in coverage across the nation, as we see the Indian Ocean Dipole strengthen, as mentioned in the video, that process is forecast to take place from now and continue throughout August and further into Spring. The quicker that signal evolves, the faster that moisture will be drawn into the nation. The climate hustler as I call it, the Southern Annular Mode, is forecast to remain the key to drawing that moisture across the nation via the polar jet surging northwards and meeting the moisture and warmer air from the subtropical jet. This process will be key to inducing larger rainfall events through the month.
For most of the state's agricultural areas the rainfall should be nearer normal with the disruptive impacts of positive SAM phases meaning the moisture that is conducive to heavier rainfall across the nation further north and east of the state. For now, it is safe to split the difference in modelling and go with a seasonal month of rainfall, with the second half of the month looking wetter than the first half of the month on current guidance. Forecast confidence is low.
The persistence of the easterly winds could lift the rainfall to a decile 7 over the eastern parts of the state with areas along the ranges forecast to be at a decile 7-8 in terms of rainfall through August. I would suspect that the wetter phase of weather comes through during the second half of the month of the current guide. Forecast confidence is moderate.
FOOD BOWL AND NSW
The wetter signal across all modelling is supported by the increasing SSTs surrounding the nation's east and north and developing down the west coast, so there is plenty of potential for widespread rainfall. The issue will be whether the easterly winds dominate, or the westerly winds return. That will dictate that higher decile rating as we move through the month. At this stage, it is looking to be along the Great Dividing Range with a focus on and to the west of the range at the moment. Forecast confidence is moderate.
A general signal of above average rainfall for large sections of QLD with August generally the driest month of the year for the state. So it won't take much rainfall to kick many regions into the decile 6-7 range. Some chance that the decile rating could be increased if we see more easterly winds develop through the month, but it is looking more likely that we will have a mixture of easterly rainfall events for the coasts and low pressure moving out of the west via the jet stream. Forecast confidence is moderate.
Starting to see a return to moisture over the northern tropics as a northeast to easterly flow redevelops with those higher moisture loads over the Arafura Sea and to the island nation's north of Australia being drawn southwards over the course of the month. The Indian Ocean continues to warm through the outlook with the chance of that moisture beginning to be drawn over the coastal areas via sea breezes and this could kick off a few showers through inland areas of the coast with convergence. A small chance of a widespread rainfall event through the northern tropics via a cloud band. Forecast confidence is moderate to high.
Some of that moisture streaming out of the Indian Ocean could begin to stream into the jet stream with some higher signals for rainfall about the eastern deserts and about the Gascoyne and Pilbara coasts. Otherwise most elsewhere looking more likely to sit at seasonal expectations. Forecast confidence is moderate.
SOUTHWEST WA AND AGRICULTURAL AREAS
A slight drier bias for parts of the SWLD and that is due to the chance of blocking developing over the east of the country through the early part of August, but it will be marginally drier. Wetter weather developing along the axis of a jet stream flowing from the Indian Ocean and I am splitting the difference in the modelling which suggests heavier rainfall chances than what I am showing, so at this stage decile 5.5-7 is fair for areas between Warburton and Kintore which represents the beginning of the Indian Ocean influence. Forecast confidence is moderate.
Temperature Outlook August 2022 - Deciles (White Zones are areas that are forecast to be at a higher chance of seeing seasonal values with numbers scaling up and down from that point leaning warmer or cooler)
The temperatures are forecast to be fairly similar to the spread we have seen in July, but there will likely be warming over the interior and parts of the northwest as we see that dry air and warm air that has been dammed over parts of far northwest Australia, drawn southeast in advance of cold fronts rolling through the south of the country. The colder the fronts, the more volatility developing in the surface pattern as we see the battle zone between the cold air and the warm air play out via the jet stream.
SOUTHEAST AUSTRALIA - AGRICULTURAL AREAS
Generally seasonal conditions for much of the nation's east and southeast with a fair degree of variation in temperature. The modelling suggests that we will see a cooler bias continues from July into August over interior parts of the NT and through western QLD but that won't be having as much of an impact on the southern states. Forecast confidence is moderate to high.
The jet stream is likely to become more active with cloud and possibly rainfall spreading from the northwest of the nation through to the southeast of the nation leading to a cooler bias through the southwest and southern parts of QLD and extending back into the southern NT. Warmer bias developing over the northern tropics with the elevated SSTs surrounding the north leading to that increasing warmer bias. Forecast confidence is moderate.
A warmer bias is set to unfold over the tropical north with the elevated SSTs surrounding the north leading to that increasing warmer bias. We will likely see this increase the humidity values too which may induce the early build up setting. Cooler bias over the Central Australia region is conditional upon the jet stream cloud band coming into play with more cloud cover and higher rainfall chances more often than not. Forecast confidence is moderate.
The warmer bias starts to develop over parts of the Kimberly with that warmer bias possibly sinking further south if the jet stream influence is not as acute as what is being advertised. The cooler bias over the eastern deserts is in relationship to the developing jet stream carrying more moisture and cloudy conditions across the nation from west to east. In the white zones, a stronger signal for seasonal conditions with a decile of 5.5. Forecast confidence is moderate.
SOUTHERN AUSTRALIA AND CENTRAL AUSTRALIA
Southern Australia is currently sitting under a guidance of seasonal conditions for the month with a cooler bias and guide being found over Central Australia, this nosing into the northern districts. There will be fluctuation in temperatures, but the overall trend is for no strong pull towards a colder or warmer bias at this time. Forecast confidence is moderate.
WESTERN AUSTRALIA AND AGRICULTURAL AREAS
The models are signaling a relatively seasonal month of weather for much of southern and western areas of the state but there is a chance that temperatures may be warmer along the west coast and adjacent inland, that is thanks to the elevated SSTs which are being observed offshore the coast. A cooler bias for the eastern deserts is in relationship to the coverage and influence of the Indian Ocean Dipole. Forecast confidence is moderate.
Refer to the video for further information but also check back daily to the weather information and don't just look at a longer-range forecast and expect this to be gospel. That is poor interpretation of data and my forecast. This forecast is a guide for those wanting to see the trends.
More coming on Tuesday with the higher resolution data which has started to swing back wet for the east and southeast inland plus the southwest and northern areas of the nation too - but I want to see the data on Tuesday to verify a shift in the guide before drawing more green and blue on the charts.