BANGOR, Maine — Attendance mimicked the weather Saturday as an all-day music festival concert kicked off the 2011 Waterfront Concerts series at the Bangor Waterfront Pavilion.

The crowd numbered in the high hundreds under cloudy, gray skies and steady breezes as music started to blare from the secondary sound stage around 10:30 a.m. But as the temperature rose and the sun came out, that number climbed to about 4,000 as people began arriving to stake out prime areas to sit or stand for the main attraction.

The revamped, resized and relocated Bumstock music festival — a University of Maine staple for decades — featured 15 bands from Maine, New Hampshire and Massachusetts that batted leadoff for the heavy hitters headlining the national Avalanche Tour: Stone Sour, Theory of a Deadman, Skillet, Halestorm, and Art of Dying.

“We have bands from Bangor, Falmouth, Calais, Portland, the Orono-Old Town area, and a few bands from out of state as well,” said Robbie Snow, Waterfront Concerts production manager. “I think 12 of the 15 bands are from Maine.”

The festival already is seen as a big success, not only in terms of the lineup and the fan support and ticket sales, but also because of the response from bands.

“Not only are bands willing to travel to play here, but there were nearly a hundred others who contacted us to play, but we only have so many slots to fill and so many hours in a day,” said Snow. “We’re already full up for Oxxfest.”

Oxxfest is a similar festival-concert event planned for the Bangor Waterfront on Sunday, July 31. Previously, it was held in Oxford and Wiscasset.

Waterfront Concerts promoter Alex Gray confirmed that this year’s fourth annual Oxxfest event will be headlined by Stone Temple Pilots.

“We’re going to announce more acts, but that’s the biggest headliner we’ve ever had for Oxxfest,” Gray said.

Concert promoters and safety-security workers reported no major problems Saturday afternoon, other than a few technical or weather-related difficulties.

“I don’t know about easier, but it’s going a lot smoother,” said Snow. “We’ve learned a lot and we know how to handle situations better. It’s the first show, so we have some hiccups in terms of weather, stage setup and fencing along with some late-resolved Internet issues.

“We also had to open the gates later than expected because we had some buses arrive late from New York, but the crowd was patient and people were great.”

Bangor police Officer Brad Johnston reported no serious problems as the all-day event headed into its seventh hour. There was a report that a couple of fans received lacerations or bruises in the mad rush to stake out a prime spot up front when security began allowing fans inside the main stage area about an hour before the Avalanche’s showtime.

“The crowd’s been very good and we really haven’t had to do anything to this point,” Johnston said.

Gray confirmed that one of the Waterfront workers suffered a broken ankle during setup work earlier in the day.

“The biggest thing for us was the mud. We got a lot of rain the last few days,” Gray said. “When you put a 25,000-pound forklift out there trying to lift 5,000 pounds, it’s going to sink in this stuff. That’s why we put a lot of sand out there in the front of the stage, because it was so wet.”

At least a couple of intoxicated fans were kicked out by police, one for punching another man during the break between Skillet’s set and Theory’s.

The fan count was estimated by several security workers and police officials to be 8,000. Because of Avalanche Tour contractual obligations, Gray is unable to release an official crowd count.

Saturday’s alcohol sales were handled differently from traditional concert events that feature one or two acts because of it being both an all-day event and an event that draws fans of both legal and illegal age for consumption of alcohol.

The format used a “beer garden” setup where beer and wine sales were held at concession stands fenced off and segregated from the rest of the arena, forcing fans to drink in one designated area.

“Events like this tend to skew really young, and when it’s this young, you want to take away any temptation or tomfoolery that’s going to come from alcohol consumption,” Gray said.

“It’s an all-day show and it’s general admission with big age differences in the crowd, and people can conceal alcohol easier standing as opposed to sitting,” Snow said. “For other shows, people can buy two drinks at a time and take them to their seats, but we have to control these kinds of shows more tightly.”

Saturday’s Bumstock festival featured the bands A Constant Bubble, The Marble Socket, Bury the Myth, Deliver Us, Nobis, Sufferer, Salvo, Darkside Out, Indecent Exposure, A Day’s Confession, Prospect Hill, Shallow Path, Upon Victory and End of Idols.

Southern Maine band Uncle Jack sold the most tickets of all the local bands

“There aren’t a lot of large venues for local bands, especially those that do original material, to play at, and this also allows bands to meet, network and socialize,” Snow said. “And this is a chance for them to add to their resumes and get more exposure.”

The evening’s headliner session started just after 6 p.m. and went off almost incident-free, although there was a power problem that caused a four-minute break in Theory of a Deadman’s set, but lead singer Tyler Connolly used the time to talk and joke with the crowd.

Although Stone Sour was the last to play, about two-thirds of the crowd seemed to be there to see Theory.

Many people started leaving after 10 either to beat the crowd or get a jump on the drive home while Stone Sour was still playing. The concert ended about an hour later.

In another show-related event, a meet-and-greet public session featuring four drummers from the headline bands of the Avalanche Tour at Mark’s Music store in Brewer drew about 250 fans from 3 to 4 p.m.

“People started lining up around 1:30 p.m. and things went very smoothly,” said store owner Mark Braveman. “We had a photographer here taking photos of the drummers with fans, and we sold out of head covers.”

The event was co-sponsored by Mark’s Music and Sabian cymbals, a main sponsor of the Avalanche Tour.

“From our perspective, events like this are great ways to promote the musicians, the bands, the tour, Sabian and stores like Mark’s, so they’re great promotional events,” said Katie Robinson, e-marketing coordinator for Sabian.