When you want a different forecast, try the Norwegian one. just as likely to be right, though eveb it has low cloud for the relevant days
http://www.yr.no/place/United_Kingdom/Scotland/Fort_William/long.htmlWent into Barisdale last year towards the end of May and both the BBC and the Norwegians gave very iffy forecasts. They both agreed that one four hour period in the four days would be OK, but different ones, so we didn't know when to head for Slat Bheinn, our main reason for being there. As it turned out, we could have done it on either of the last two days, which were 5 & 6 days hence at the last internet connection before we got to Kinloch Hourn. End of May is a bit distant to get an accurate forecast from anyone...but many of the sub 2000s are well worth a visit, maybe incorporating into a longer walk.