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."
Light winds were forecasted for the Arm this afternoon, with Bird Point registering a 2 mph to 4 mph southeast breeze about noon. Since it's blowing from the Portage area, the wave might get a slight boost.
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.
"Today was my first time out here, so I didn't know what to expect," said Wasilla paddleboarder Joe Gibson. "It went right under me. But I rented the board (from REI) for three days, so I'm looking forward to giving it another shot tomorrow."
Gibson ventured out between Bird Point and Girdwood, out on the vast flats with a spectacular mountain backdrop, along with plenty of company. At least six surfers joined the paddleboarders on the chilly water.
Bore tides are nature's true "tidal waves" -- occurring when incoming tide builds into large dramatic front as it rushes into a narrow channel or river against the outgoing current. Turnagain Arm is the only U.S. locale where the bores strike with regularity, although bores can churn up Knik Arm too. The just-right alchemy of wind and current during a minus tide and a full moon can spawn 10-foot bores that travel as much as 20 mph up the channels.
Based on the park's rating system, the summer's only "five star" bore will occur today. But two more "four star" bores may come Wednesday and Thursday. The next series of "four star" bores will make five return engagements from July 2-6.
Contact Doug O'Harra at doug(at)alaskadispatch.com