An East Coast Low (ECL) rapidly developed off the New South Wales coast late Monday into early Tuesday.
These beasts bring damaging to destructive winds, heavy rain and flooding, strong to gale force to storm force winds, as well as coastal erosion and dangerous surf.
The location of the low determines who sees the effects - the wild weather is near the low and to the south. Those to the north are gusty but in sunshine.
You may have heard lots of 'bomb cyclone' or bombogenesis' - and these are technical terms for this ECL. A low pressure system is shorthand for cyclone. A high pressure system is shorthand for anti-cyclone. Tropical cyclone's are lows that develop in the tropics. Bomb cyclones are one's that rapidly develop (with central pressure dropping 24hPa in 24 hours). Essentially the 'bomb' part indicates explosive development.
Already there have been falls over 100mm since it developed, and there is more to come.

The ECL is located off Sydney on Tuesday, pushing the heaviest rain into these areas south of Wollongong:

By the end of Wednesday, the ECL is well off the coast, but the tight isobars (the lines on the map) indicate that while the severest winds have moved on, it's still very gusty. The heaviest falls on Wednesday are again south of Wollongong, extending around the corner into East Gippsland.

By Thursday it's just regular wet weather for the NSW coast with 5 to 20 mm of rain. East Gippsland may still see heavy falls as Thursday begins.
