Valid May 7th 2021 - Period May 7th-21st 2021.

Weather Matters with Karl Lijnders - Temperature Outlook for the coming fortnight.

Weather Matters with Karl Lijnders - Rainfall Outlook for the coming fortnight


  • Drier weather developing for WA with above average temperatures returning through the coming week

  • Showery and colder weather for the southeast of the nation as the long wave trough moves through the coming 5-7 days.

  • High pressure to dominate a lot of the continent over the coming 7-14 days as it journeys to the east

  • Well above average temperatures hanging on over tropical Australia.

  • Rain and colder weather to return after this period for many areas of southern and eastern Australia.

A drier and quieter period of weather is on the way for much of the nation as we see high pressure rolling through the southern parts of the nation over the coming 7-10 days, bringing a period of calmer weather, and warmer weather for a period too.

After well above average rainfall over parts of inland WA and along the east coast yet again, things are settling as upper heights come up meaning that sinking air will be dominating most of the continent, suppressing rainfall opportunities as we go through the coming 7-10 days.

Temperatures have been well below average for many locations and rainfall has been above average with many farmers rejoicing after their best rainfall for 4 years to kick off a season.

Rainfall observed earlier this week on Tuesday into Wednesday

Precipitable Water values for the first week of May showed that tropical moisture that streamed into WA. For farmers through southern Australia, we need to see repeat bouts of this over the season ahead, to maintain the ability for rainfall to remain regular, given that all climatic drivers are remaining neutral at this stage.

This week in particular for WA and SA, things will dry out and warm up. With the a strong upper high slowly moving through, this will lend itself to keeping a large part of the west rain free and cloud free. So a quiet period of weather to take advantage of all that rainfall over the past week.

However make the most of this two weeks with a shift to colder and wetter conditions developing after the 21st of May over WA with a significant set of signals pointing to major frontal weather and moisture being drawn in from the Indian Ocean once again.

Temperature anomalies for the period May 11-21 2021. GFS 18z run valid May 5th 2021.

The temperatures over the NT will remain very warm as well with above average temperatures, however drier and cooler air will reach the Top End towards the 15th of May onwards with a nice drop in overnight minima.

Euro temperature forecast for Saturday 15th May 2021 - showing that drier cooler air coming in from the south to drop overnight temperatures.

Euro temperature forecast for May 16th 2021 - showing the heat being shunted to the far north of the Top End with drier air in place, to bring down the apparent temperatures over the region.

In contrast, cooler weather for the coming week is expected over southeast Australia with a series of cold fronts, potential for some cut off low pressure systems to work their way through the southeast as well, mainly through the upper levels. Models have been hinting at two systems bringing some colder air into the southern and eastern interior over recent days and they will continue to wobble on this idea over coming days, until the systems are analysed in real time.

This will lead regardless of where they go, to a cooler than normal week, with near average rainfall for coastal areas, especially through VIC and TAS where the frontal weather will have more impact.

500mb flow pattern (18000ft) showing the cut off low pressure systems and colder air set to move through southeast Australia, possibly north into QLD. GFS 18z valid 7th May 2021.

There is a wild card system in this pattern above, with colder air moving north through NSW and then into QLD, this could spark inland showers and thunderstorms, maybe areas of rainfall over southern QLD and northern NSW IF moisture is sufficient and IF the upper low does move north through to this area. It is way too far out to be certain, on that but I will pin the deterministic data below and revisit this next week to see how it stacks up.

QLD generally, dry and seasonal with cool nights and sunny warm days over the inland. Showery weather may develop about the north tropical coast and far southeast coast but otherwise it is a benign period of weather with little change in the overall synoptic scale, bar that wild card event which will be watched.

Euro 12z run 07 May 2021 - Accumulated Rainfall for the next 10 days.

The higher confidence of rainfall is for southeast Australia through coastal areas, with the light and thundery rain moving through western SA over the next 24 hours and with showers increasing along the east coast next week with an upper trough. The rainfall through QLD is very low confidence of verifying.

As mentioned, temperatures will be below average for much of this period over southeast Australia given the broad southwest flow aloft with the high pressure system coming in from the west, taking it's time, meaning that persistent onshore winds, will pump cloud, isolated showers and drizzle for the most part between frontal systems, over the region. This will mean a gloomy week on the way.

Euro Ensemble forecast for temperature anomalies for period May 11-21 showing that cooler weather persisting for a decent period coming up.

The colder than average day time temperatures will mean that areas of inland NSW and northern VIC could see an uptake in the number of frosty mornings, given the airmass will be relatively dry running over land before it arrives into the region and with high pressure ridging in, the sinking air motion will lend itself to relatively clear nights. Light winds also meaning that radiational cooling will be quite efficient.

If you have frost tender crops this is now the time to prepare for these colder nights.

Graziers should be aware a burst of colder weather mid to late next week may put some stress on young stock, with blustery winds and showery weather for coastal areas. But this should be limited to a few days and mainly areas that are coastal through VIC.

Overall there are no indications for any severe weather events over the nation during this period and fairly seasonal weather for this time of year, despite the anomalies in temperatures over the period. Not uncommon weather for May.

Next Update on Climate will be next Friday 14th of May - which will be the June 2021 outlook.

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