Snow was in the air at Cypress Mountain Wednesday, but just how long it stays on the ground and whether athletes will even be able to see it come race day remains unclear.

Ten to 20 millimetres of rain is expected to hit the Olympic mountain Thursday, and Environment Canada says another 20 to 30 millimetres could fall later that night. Ten to 15 millimetres more rain is in the forecast for Friday.

Women's moguls is scheduled to kick off Games competition at Cypress on Saturday, and athletes will be forced to contend with an additional 15 to 25 millimetres of rain.

As if the excess precipitation wasn't enough of a headache, race organizers say an even larger problem may be rearing its ugly head.

"Fog's probably the biggest concern. We have to be able to see the start," said Joe Fitzgerald, race director with the International Ski Federation (FIS).

"If the judges can't see, we don't go."

Fog rolled on and off the Cypress moguls course during a training session Wednesday night. At one point, the fog was so thick the top of the course couldn't be seen from the base. The fog was also an issue at the Whistler ski venue, where poor visibility led men's downhill training run Wednesday.

"If it just rains, (the race will) be a go for sure," said American moguls head coach Scott Rawles.

"The x-factor will be the fog. If it gets foggy, that would be the one reason you couldn't run the event since it's a judged event."

Fitzgerald agreed that while the amount of rain on the horizon isn't exactly a blessing, it wouldn't be enough in and of itself to cancel events at Cypress.

"It would take a torrential downpour and plus-15 to 20 degree temperatures to be able to take all the energy out of this snow," he said, adding the course is designed so excess liquid drains off the hill.

Wednesday's training session was a relatively light one. Canadian Jennifer Heil, ranked No. 1 in the World Cup standings, didn't take to the hill, and neither did teammate Kristi Richards, ranked No. 5.

Americans Heather McPhie, Hannah Kearney, and Shannon Bahrke, ranked second, third and fourth in the World Cup results respectively, also stayed off the mountain.

Another U.S. skier, Michelle Roark, did take to the hill and spoke glowingly of the conditions.

"The course is actually really nice," she said. "I mean, (Wednesday) was much different than (Tuesday) and it's probably much different than it will be (Thursday) but the people here have done an amazing job with the course."

On Tuesday, Canadian moguls skier and gold medal threat Alexandre Bilodeau went so far as to call a training session earlier in the week the worst training run in the history of moguls.

Games organizers remained steadfast Wednesday that the field of play will be of Olympic calibre.

"The sport team, the sport operations and the sport management team are prepared for rain, that's what we had all of January, that's where most of the snow went originally," said Stephen Bourdeau, a venue spokesman.

"So they have tarps, they have reflective tarps for the sunshine, they have white tarps for the rain, and they literally have enough tarps for the field of play to protect it from the water."

Cypress Mountain, which will host snowboarding events during the Games in addition to freestyle skiing, has been plagued in 2010 by warm temperatures, lack of snow and heavy rain.

But Bourdeau said organizers are optimistic after the previously snow-barren mountain was hit with about five centimetres of powder Wednesday. Rain had originally been in the forecast.

"We'll keep our fingers crossed that it will be snow (Thursday)," he said.

The lack of snow has forced Games organizers to reduce the number of training days given to Olympic athletes.

When reporters were first allowed on the mountain Tuesday, the areas around the course sat brown and devoid of snow, since any available powder had been shifted to the field. Snow has also been brought in from other B.C. hills via dump truck and helicopter.

It was a different picture at Cypress on Wednesday, when trees lining the mountainside were painted white, with snow falling off branches that had suddenly become heavy with precipitation.

With the opening ceremonies set to kick off on Friday, Bourdeau said nervousness about the weather is a luxury he and the other venue planners can't afford.

"Being nervous is not going to help things at all. It's going to cause panic and it's going to stress a lot of people out more than they're already stressed," he said.

"At this point, we've just got to bunker down and get it done."