Surf is rising and the city is preparing for thousands of spectators to converge on Waimea Bay in anticipation that the Quiksilver in Memory of Eddie Aikau big wave surf competition will go on Wednesday.

The National Weather Service issued a high surf warning starting at 6 p.m. tonight through 6 p.m. Thursday.

The giant swell is expected to bring 25- to 35-foot surf overnight, rising to 40- to 50-foot wave faces on the North Shore on Wednesday.

Winds are expected to be light in the morning and become northerly at 10 to 15 mph in the late morning and afternoon.

“It should be up to 40 feet around sunrise and continue building,” said Maureen Ballard, a meteorologist with the Honolulu office of the National Weather Service.

The weather Wednesday should be similar to today, Ballard said, with light winds and little chance of rain.

The official decision on whether to hold the contest, which is only held when wave heights are consistently around 40 feet (20 feet by Hawaiian standards) will be made Wednesday morning.

But preparations to handle the crowds have already begun.

Up to 30,000 people crowded Waimea Bay in 2009, the last time the Eddie was held, and it took up to 5 hours to drive to the North Shore on the two-lane Kamehameha Highway.

Similar or bigger crowds are expected Wednesday.

The state suspended construction projects on Kamehameha Highway on Wednesday so there will be no lane closures. Grace Pacific Corp. also suspended work on a repaving project on Kaukonahua Road so that the road can remain open.

Honolulu Police announced plans to add extra officers to assist with traffic flow and to tow illegally parked cars along Kamehameha Highway to keep the side of the road clear for pedestrians and for emergency vehicle access.

There will be no parking at Waimea Bay and contest organizers will provide free shuttles from Kaiaka Bay Beach Park to Waimea Bay Beach Park from 7 a.m. until 6 p.m.

The Bus will also add extra buses to the North Shore routes.

However the shuttles and the city buses will likely still be caught up in the delays on Kamehameha Highway.

For more information on the extra buses go to thebus.org.

“There will be an enormous amount of pedestrian and bicycle traffic along Kamehameha Highway throughout the day Wednesday, and we ask drivers to be aware of their surroundings and heed extra caution as they make their way around the North Shore,” Mayor Kirk Caldwell said in a news release. “We want this big wave competition to be safe, not only for the surfers involved, but also the thousands of spectators that are expected.”

Trash and bulky item pickup along Kamehameha Highway will also be affected. Refuse workers will service Haleiwa Beach Road, but will remain off of Kamehameha Highway and Joseph P. Leong Leong Highway on Wednesday. Workers will complete the Wednesday pickup over the next several days and expect to have all bins picked up by Saturday.

Those going to the North Shore early in the morning to secure a parking space should bring warm clothing. Ballard said overnight conditions will be chilly, with forecasts calling for lows around 55 degrees on the North Shore.

Spectators should remain far from the surf, Ballard said. The swell could bring dangerous shorebreak that can sweep people into the ocean.

City lifeguards will begin work at 7 a.m. at Waimea Bay and Ka Waena to keep crowds away from the shore break.

“Large breaking surf, significant shorebreak, and dangerous currents could make entering the water very hazardous,” the weather service said. “Anyone entering the water could face significant injury or death.”

For those who want to watch the contest, but avoid the crowds, the event will also be broadcast live on WorldSurfLeague.com.

The high surf warning affects north and west shores of Kauai County, Oahu and Molokai, and north-facing shores of Maui.

Surf on west shores is expected to build to 10 to 15 feet tonight, and 25 to 35 feet Wednesday through Wednesday night.

On Kauai, county officials are advising no swimming at all north shore beaches west of the Hanalei Pavilion to Kee Beach because of the high surf and dangerous ocean conditions.

Spectators are also advised to use extreme caution because of large breaking waves that can make it dangerous for people standing along the shoreline.