Just a reminder about the ESB’s useful page of hydrometric information here.
As of yesterday morning (23 February 2020), the discharge through Parteen Villa Weir was 659 cubic metres per second [cumec]. That’s the total discharge from the Shannon, covering both what goes through Ardnacrusha and what goes down the original course of the river [which in summer gets 10 cumec].
Of that 659, Ardnacrusha was getting 381 cumec, which means that 278 was going down the river’s original course.
The ESB’s Shannon forecast says
It is expected that a discharge ranging between 315 [cumec] and 370 [cumec] will be necessary at Parteen Weir over the next 5 days based on current weather forecast.
Those figures are well below the current combined discharge of 659 and more rain is expected, so I presume that the forecast refers to discharge down the original course of the river, which is to increase by between 13% and 33%. Water levels below Parteen Villa Weir are already high, though not at 2009 levels, so an investment in wellies might be advisable.
Shannon floods 2009 here.
Here’s an old page of mine about why the Shannon floods. I’ve removed some links that no longer work. The link to the ESB’s infographic does still work.
Irish waterways history 