IT MAY have been slower moving than expected and allowed many grain growers a precious extra few hours harvesting, but the monster storm set to swamp south-eastern Australia is beginning to make its presence known.
To 10pm Thursday night eastern time there had been falls of over 10mm recorded on South Australia’s Yorke Peninsula, through that state’s south-east and in the far west of Victoria.
It is only the tip of the iceberg of a system expected to dump up to 300mm over parts of north-eastern Victoria and southern NSW.
Bureau of Meteorology (BOM) duty forecaster Richard Russell said the combination of climate drivers that have led to the storm, described as a one in a generation event in some parts of south-eastern Australia, are rare.
“It is very significant, something you don’t see very often,” Mr Russell said.
He said the record run of November warmth in southern Victoria had led to the build-up of humidity that is providing much of the moisture for the rain event, which is likely to have disastrous effects for impacted croppers.
“Normally you see some sea breezes but southern Victoria has had this humidity for weeks, it has been very tropical and the system has fed into this source of moisture.”
He said prior to the major event there had already been a sustained pattern of afternoon thunderstorms developing somewhere in Victoria.
While the Garden State is expected to cop the brunt of the rainfall, other areas will also receive heavy falls.
“South Australia, Tasmania and NSW will also be wet,” Mr Russell said.
The patchy showers that have arrived in Victoria now are part of an upper trough system, before the low deepens over north-west Victoria overnight.
Heaviest falls are expected on Friday morning in Victoria’s west, moving through the state during the day.
There will be follow up rain bands on Saturday and Sunday.
Mr Russell said he expected the rain to be heaviest in Victoria’s north-east.
“It grades heavier as you go east, but even the far west and north-west of Victoria could see 60-120mm, which is very significant.”
“Many regions will see more than their entire average summer rainfall in one dump.”