Spectacular bore tides have rolled through Turnagain Arm this week. Check out the first three minutes of this KTUU video for several views of the phenomena taken May 5, when the combination of a minus 2.5-foot tide conspired with the full moon to generate a big wave.
Alaska Zoo photographer John Gomes made it to Bird Point with his gear and caught pictures of the bore tide climaxing as surfers rode the waves Monday evening, according to this KTUU story. "It was a great bore tide for me," Gomes said. "This is only the second one I've seen — I was impressed."
Bore tides are nature's true "tidal waves" — occurring when the incoming tide builds into a large dramatic front as it rushes up a narrow channel or river against the outgoing current. Turnagain Arm (and sometimes Knik Arm) are the only U.S. locales where the bores strike so big. With the right recipe of wind, current, a minus tide and full or new moon, bore tides can reach 10 feet or more while sweeping along at 10-20 mph.
Chugach State Park posts a bore tide schedule, with predictions of the best times to catch a mondo wave. "Bird Point is a good place to watch the bore wave on its twice-daily sweep of Turnagain Arm," the schedule explains here. "The bore wave typically shows up here two hours 15 minutes after low tide in Anchorage. It can vary up to 30 minutes or more depending on wind speed and direction. 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."
Based on the park's one-star to five-star rating system, the chances of a large bore flushing Turnagain's silty channels will subside through the weekend and essentially become zero early next week before starting to improve again the week of May 19. But the next best shot at witnessing something epic falls between June 3 and June 7, with the summer's only "five star" bore forecast for Bird Point at 5:41 p.m. on June 5.
Contact Doug O'Harra at doug(at)alaskadispatch.com