LIGHTNING, torrential rain and a combined 73-minute delay – no wonder Adelaide coach Matthew Clarke described Saturday's semi-final with Collingwood as a "truly bizarre day".

The Crows defied the elements to defeat the Magpies by 12 points and advance to next Friday night's preliminary final against Brisbane at Metricon Stadium.

The start of the Unley Oval encounter was delayed by 30 minutes due to lightning before a severe thunderstorm just before the quarter-time break forced another 43-minute break before play resumed.

"I am super proud of the group how they managed what was a truly bizarre day," Clarke said.

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"As much as possible, we wanted to control what we have control over and don't let the distractions of the day take away your focus. 

"That was the most pleasing thing, our ability through what was these unique set of circumstances to keep coming back and play pretty decent footy."

The Crows kicked two goals in the opening quarter before lightning strikes appeared in the distance late in the term.

Officials decided to complete the quarter rather than leave the ground immediately.

"We saw the flashes, it's hard to know how far away that is, but once we saw that, it was pretty clear we were going to be going off again," Clarke said.

"I just wasn't sure whether they were going to call it straight away or wait for the (quarter-time) break.

"They're a pretty relaxed group and we already had the experience of the game being pushed, so we basically took the same approach.

"There's not much value in getting excited about what's ahead, just stay relaxed, and (the players) do that pretty well."

The Crows now turn their attention to the Lions with captain Chelsea Randall almost certain to return after she was contentiously ruled out of the semi-final with concussion.

"It was disappointing for her, but once the decision was made, she got focused on helping her teammates and the positive is, she'll be fresh," Clarke said.

For the Magpies, it's the end to another impressive campaign without reaching the decider.

"This is our fourth season of finals now, we keep being thereabouts, but we just can't get the job done at the end of the season," Magpies coach Steve Symonds said.

"We've had a real battle this week, we were pretty sore and banged up after last week.

"A number of players were under the pump and got themselves up for the game.

"The way they fought it out, particularly in the second half, I'm extremely proud of the group."

Of the unique conditions, Symonds said: "Gee, we had everything today.

"Stop, start, on and off the field, everything happened.

"We'll probably look back in a few years and have a chuckle about it."