An upper low has finally started to lift out of Victoria and is now moving through inland NSW on Tuesday.
Widespread rainfall has been observed through southern and eastern Australia in response to the upper low moving through the region.
With the colder air today, thunderstorms are likely over a wide area of the east, but they will be isolated in nature. Large amounts of small hail is possible with these slow moving thunderstorms which could cause some damage to crops.
Weather Matters - Thunderstorm Forecast for Tuesday May 4th 2021.
Surface based instability is rather limited over parts of the east today, in contrast to Monday, where we have more cloud in place and temperatures are much more below average over the coming day or so. Yesterday we saw temperatures well above average, which added the necessary energy to get the storms going last night over southern and central NSW.
Cape Values on Monday 3rd May 2021 Euro.
Cape Values on Tuesday May 4th 2021. Numbers are negligible in contrast to Monday meaning that thunderstorms will pulse type IF they form with little dynamic forcing in place.
Note the dry air being pulled from the south and through parts of SA and into western NSW and VIC. This dry air will move right through the eastern inland, resulting in clearing skies and cold nights on the way as winds turn calm.
But in the east, the moisture profile will improve with the onset of easterly winds as the upper low deepens and a weak surface low forms along a trough off the NSW coast.
Locally heavy rainfall is possible about SE NSW and East Gippsland during the next 48hrs where some flash flooding is possible.
Strong storms are also possible over the NE of NSW and SE QLD on Wednesday with small hail and strong winds possible. The upper low will be dropping upper air heights well below average for this time of year and running into modest amounts of moisture, setting the stage for unsettled weather.
Euro upper air chart - 500mb (18000ft) showing that upper low well north of where they usually travel. Can make for dynamic weather if all the ingredients are in place.
Interesting weather signals into mid month.
GFS Precipitable Water for the next 2 weeks - ending May 19th 2021.
GFS is standing alone on the latter part of it's run with the chance of a major inland rainfall event, however it cannot be discounted with this being peak upper level low season over the south of the nation, as the westerly wind belt moves further north and interacts with relatively warm weather over the mainland.
Moisture in the easterly winds are still above average given the above average sea surface temperatures off the east coast, so that will help to bring in more moisture to work with, IF easterly winds feed inland troughs over coming weeks.
GFS Rainfall for the next 2 weeks - 18z run. Most likely the inland rainfall will be gone in the next 00z run at 4pm.
In contrast I am not factoring in that rainfall over the east, with near average conditions expected for most of the east over the coming fortnight. The wettest weather over the coming period will be in the next 2 days over SW WA and through SE NSW.
Weather Matters forecast for the next 2 weeks - Valid May 4th 2021.
Temperatures near or above average over large parts of eastern Australia with those coastal areas over VIC and TAS likely to see near or below average temperatures over the coming fortnight. This is fairly normal with the transition into winter type synoptics. Hot weather over northern Australia will moderate over the coming week.
Weather Matters - Temperatures for the coming fortnight ending May 19 2021.
So the areas that need rainfall are still waiting, that is through SA and points towards western NSW and QLD. There are not great signals for that to change over the coming fortnight.
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