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.