Updated

By Mark Lamport-Stokes

SAN DIEGO (Reuters) - Players at this week's San Diego Open will have to tackle two courses playing extra long after surprisingly heavy rainfall in the area over the last week.

The picturesque North and South layouts at Torrey Pines have been saturated by just over four inches on a part of the California coastline that usually receives a total of 10 inches for the entire year.

Around 20 trees were uprooted by strong winds last week and the rough on each of the two par-72 courses has become much thicker, thereby increasing the penalty for wayward shots.

"The fairways aren't going to roll out as much and it (the rain) makes the courses play longer," American Brandt Snedeker told reporters on the eve of Thursday's opening round.

"It'll make it brutally tough because the rough will be super thick. And it changes each year here depending on the weather.

"A couple of years ago when I played really well here, there was hardly any rough at all," he added, referring to his third place in 2007 when he tied the North Course record with a sizzling first-round 61.

"It was really dried out and baked. But the last couple of years there has been a lot of really thick rough and that makes the golf course play that much longer, that much tougher."

TREE DEVASTATION

"They've lost a bunch of trees," the 27-year-old said. "You see a lot of roots coming out of the ground, a lot of trunks, and that's just terrible.

"But the course itself looks great and the fairways are perfect. You're getting no roll and it's going to play long and difficult but ... there's not much mud on the ball."

With a favorable weather forecast for the rest of the week, Haas predicted generally low scoring for the fourth event on the 2010 PGA Tour.

"There will be guys every day that shoot probably five or six under (on the North Course)," he said. "I'd say for the majority on the South Course, even or one under (par) is a great score."

The brutal 7,698-yard South Course, which staged the 2008 U.S. Open, has always provided a much tougher test than its 6,986-yard North neighbor.

(Editing by Peter Rutherford)