I'm into the weather a bit (especially storms) and so I use weather models to form my own forecast much of the time rather than using sources like the BBC. Usually I find that the weather forecasts on the TV and online tail behind what the weather models currently show.
The weather models at this time currently show a spell on rain on Friday evening with this clearing through to the east overnight into Saturday morning. In general, it should become brighter by lunchtime - but with the lifted index being around 0 to -1 this means that heavy showers will likely crack out from lunchtime onwards. Shows will generally become more organized as the afternoon goes on - but with clear slots in between I would think.
Upper level winds are generally from the SW on Saturday and this usually means that any showers that form over the Irish Midlands will tend to track NE towards Co.Antrim. Though lately, I've found that in thundery scenarios a lot of the activity has been to the west of Lough Neagh and this may well happen again.
One thing that Newcastle has is the Mourne's nearby and they can assist cloud formation and strengthen showers due to orographic effect (air rising up over the mountain slopes). This could make cloud cover / showers more prevalent there than in other areas in the east of NI.
Taking all that into account though, I see it as a 50/50 situation where if we are lucky, a good part of the afternoon may avoid showers. But always with showers nearby! I'll make a final call on it when I see the weather model output on Friday evening and see what the situation actually looks like on Saturday morning.
Really want to go to the show as there is a possibility I think, that this will be our last chance to see the Vulcan fly here.