Tries from Tommy Bowe and Paul Steinmetz and 13 points from the boot of Humphreys saw Ulster home in a game marred by wind and rain.
In difficult conditions it was David Humphreys who was the key for Ulster kicking 13 points and opening the scoring after six minutes with the first of three penalties. However Paul Warwick quickly responded to level the scores and soon bagged a second successful kick but the visitors lead was short lived as Tommy Bowe dribbled over a Tyrone Howe Chip to score the first try, Humphreys converting from a difficult angle.
However Warwick narrowed the gap with this third kick 10 minutes before the break – the final scoring act of the half.
With rain adding to the already difficult conditions Humphreys kicked a monster 50-metre penalty before Paul Steinmetz got the second score which Humphreys again converted to make it 20-9.
However the visitors were far from finished and, after battling into Ulster’s 22, a chip by Chris Keane was collected for an unconverted score by Bernard Jackman to cut Ulster’s lead to six points. However, it was Humphreys who had the last word with a injury-time penalty.