The biggest bore tide of the 2012 season will overrun Turnagain Arm’s silty channels late this afternoon, according to the official bore tide schedule posted by Chugach State Park. But whether this moon-boosted phenomenon arrives as an epic mondo wave with a churning face suitable for surfing -- or as a smaller white-capping roller -- depends on the vagaries of wind.

With Minus 4.1 feet tide forecasted for Turnagain Arm, the bore tide is expected to pass Bird Point near 5:31 p.m -- about two hours and 15 minutes after low tide in Anchorage. Other big bores may hit Wednesday and Thursday too.

"It can vary up to 30 minutes or more depending on wind speed and direction," the Chugach park primer warns. "Check the wind. If the wind is blowing from Portage, the bore will be larger but a bit late. Wind from Anchorage brings earlier, smaller bores."

The bore that sloshed Turnagain just before 5 p.m. on Monday brought out a pack of adventurers, each hoping to catch some white froth for ride up the arm.

Read the full story and check out bore-tide surfing video.