Heavy rain and thunderstorm activity is going to track slowly across southern and central NSW this week, bringing an increased threat of both flash flooding and river flooding.
The Bureau of Meteorology issued a 'Flood Watch' just after 1pm on Monday, highlighting that there is a possibility of river flooding in a number of catchments through southern and central parts of the state.
The river valleys included in the warning include the Hawkesbury-Nepean, the Queanbeyan-Molonglo, Murrumbidgee, Lachlan and Macquarie. All rivers in the South Coast district of NSW are also included.
The 'Flood Watch' is a 'heads up' for future possible flooding and differs from a 'Flood Warning', which is issued by the Bureau when a river is actually in flood.
There is however a significant risk of flooding through southern and central parts of the state, as a slow-moving low pressure trough edges into NSW during Tuesday from its current position over South Australia and Victoria. High levels of atmospheric moisture ahead of the trough increases the potential for heavy rainfall and thunderstorms, which could initially bring flash flooding. The slow-moving nature of the trough will allow rain totals to build
over the river catchments through the middle part of the week, with widespread 100mm rain totals possible across much of southern and central NSW.
For Sydney and its surrounding river catchments, the heaviest rain is expected to arrive during Thursday, so it will be from this point that flooding becomes a more pressing concern for residents of this region.
© Weatherzone 2012
09:31 EST The New South Wales State Emergency Service (SES) says it has received about 1,000 calls for help since a severe hail storm hit Sydney and the Blue Mountains late yesterday, adding to the backlog created by a powerful east coast low earlier in the week.