The Reds followed up their impressive success at Reading on Saturday with another hard-fought victory against one of the division's promotion hopefuls.
Robert Earnshaw struck twice, either side of a Jon Parkin effort for Preston, to secure a precious three points that edged Forest further away from the relegation zone.
With the rain pouring down, the decisive factor in this match was always going to be who best came to terms with the difficult conditions.
But during a dour opening 25 minutes, neither team managed to master the soaked, slippery pitch, with a looping, improvised shot from Luke Chambers the only effort on goal from either side.
Forest began to provide a slight air of menace with Lewis McGugan lashing a skimming effort narrowly wide as the game suddenly sprang into life.
McGugan saw another long-range effort charged down following a Forest corner and Chris Cohen saw Andy Lonergan claim the ball at the second attempt after he had bent in a vicious shot from the edge of the box.
Ross Wallace did furiously appeal for a Preston penalty but referee Peter Walton felt that Kelvin Wilson had won the ball with his desperate, sliding tackle in the box.
But it was Forest who looked the more likely to make the breakthrough with an Earnshaw header almost causing Andrew Davies to deflect the ball into his own net.
Barry Nicholson offered a riposte for Preston as he lashed a low shot inches wide early in the second half.
But it was Earnshaw who, after heading a warning wide of the post a few minutes before, finally put Forest ahead in the 58th minute after powerfully arching his back to connect with a Joel Lynch cross with a downward header that bounced high into the back of the net.
Forest's lead lasted only five minutes, however, as the home defence failed to deal with a Wallace corner fired towards the far side of the six-yard box where Parkin was on hand to sweep the ball home unchallenged.
Preston did not have parity for long either, however, as an awful back pass from Davies allowed Earnshaw to close down keeper Lonergan and guide his attempted clearance into the back of the exposed net from the edge of the box for his second goal of the game.
Only a spectacular save from Lonergan prevented Forest snatching a third as Paul Anderson fired in an angled header towards the bottom corner.