Nowland followed up Callum Davidson's scorching 30-yard strike as North End won 2-0.
Nowland might have been on the score-sheet as early as the tenth minute but he was denied by a super save from home keeper Ben Williams after he had burst through on goal.
Crewe offered little up front but when they did Eddie Johnson - on loan from Manchester United - was their best bet.
The striker had a shot blocked by Claude Davis and he forced North End's Carlo Nash to make a sharp stop low down.
But they were rare moments of threat from Alex who have now lost four games on the trot and are deep in relegation trouble.
They failed to clear the ball from their box on at least two occasions before Richard Walker's clearing header fell at the feet of Davidson who unleashed a ferocious low drive into the bottom corner in the 24th minute.
David Nugent should have made it two on the half-hour mark when he was put clear by Nowland. But the former Bury man prodded a disappointing effort the wrong side of the post.
Nowland made no mistake though after some atrocious defending by Crewe in the 37th minute.
From an Alex throw-in on the right, Adie Moses tried to give the ball to Nowland who darted in between two defenders and then beat Williams with a low shot from what looked an unfeasible angle.
Davidson also headed onto the roof of the net as Preston called all the shots in the first half.
Crewe were marginally improved after the break but they struggled to make a mark inside the visiting box. Keeper Nash had little else to do.
Luke Rodgers was thrown on for the final 20 minutes but the former Shrewsbury man failed to do much better than Michael Higdon who he had replaced.
And it was Preston who could have added a third late on when a misplaced pass from Darren Moss allowed Lewis Neal in on goal only for the former Stoke midfielder to shoot straight at Williams.