Although the first signs of vernal equinox may be late bloomers this week, there was no shortage of blossoming on the festival front. With the first major festival of the season under our belts, let’s look ahead to what lies ahead in our futures. Many lineup announcements have been flying in from both sides of the Atlantic, with Reading and Leeds, Northside Festival, Summer Camp, Sweetlife, and Heavy T.O.

Camp Bisco joins the ranks of festivals celebrating big anniversaries this year, with their 10th edition attracting big names, while the Hangout Festival continues to add A-list acts to its bill beneath the Mason-Dixon Line. The pleasant surprises didn’t end there, The Gathering of the Vibes managed to draw a diverse offering including Elvis Costello and Jane’s Addiction to its jam-based lineup.

For the full recap on the latest festival news and rumors, scroll down and check out this week’s edition of Festivals in Brief. And don’t forget to bookmark Festival Outlook and/or follow us on Twitter in order to stay informed every day of the week. After all, Wednesday only comes once a week.

NEWS:

— A dance act will headline this year’s Lollapalooza, according to founder Perry Farrell.

— Brooklyn’s Northside Festival landed Beirut and Sharon Van Etten as headliners for its 2011 edition. Other confirmed acts include Allo Darlin’, Deer Tick, and Twin Sister, with over 200 names still to be announced. This year will also feature a DIY film competition for shorts and features, and another CoS showcase! Early bird tickets are now available for $60 via the festival’s website.

— The initial lineup of the Gathering of the Vibes festival includes Elvis Costello & The Imposters, Jane’s Addiction, moe., Furthur, John Butler Trio, and Dark Star Orchestra. Passes are available at the festival website. Another installment of acts is expected to be announced in the next few weeks.

— Joining Def Leppard, Rob Zombie, Linkin Park, System of a Down, and others at England’s Download Festival will be glam-rockers The Darkness. The band announced it is reuniting to play their first show in five years. The festival is set to take place in Leicestershire, England, runs June 10-12. Three-day passes are now available via seetickets.com.

— The Hangout Music Festival’s organizers somehow found a way to make an already jam-packed lineup even better. The Avett Brothers, STS9, Mofro, Grace Potter and the Nocturnals, and Brandi Carlile are among the Gulf Shores, AL-based festival’s latest additions. Head over to the festival’s website to snatch a three-day pass for $174 while you still can.

— Camp Bisco announced the initial lineup for its decennial; Cut Copy, Wiz Khalifa, Disco Biscuits, Bassnectar, and Pretty Lights are among the 100+ performers making an appearance at the Indian Lookout Country Club in Mariaville, NY this summer. Although more acts are expected in the following weeks, early bird tickets are available now for $140 here.

— The Reading and Leeds lineup announcement assured an appropriate end to the summer festival circuit. Muse, The Strokes, Jane’s Addiction, The National, and My Chemical Romance will play alongside an impressive undercard that includes Interpol, The Kills, Odd Future, The Offspring, Deftones, The Streets, Two Door Cinema Club. Tickets for bothReading and Leeds are on sale now for £192.50 via seetickets.com.

— 311’s Pow Wow Festival is scheduled to hit Florida’s festival hotspot Live Oak (already home to Bear Creek and Wanee) this August 4th-6th. Although other lineup details are forthcoming, 311 will be playing four sets including Transistor in its entirety. The festival will coincide with a nationwide tour the band will be making with Sublime with Rome. A fan pre-sale begins today, and Pow Wow passes can be obtained at SeatGeek.com.

LINEUP ADDITIONS:

— Rock in Rio (Brazil): Added Guns N’ Roses

– Outside Lands Festival: Cut Copy (Rumored)

— Rock On the Range: Day-by-day schedule revealed

— Beale Street Music Festival: Daily set times announced

— Rock Werchter (Belgium): Added Queens of the Stone Age

— Lollapalooza: Tennis (Expected), A Perfect Circle (Rumored)

— Heavy MTL: Added Kiss, Motorhead, Billy Talent, Anthrax, and Opeth

— Summerfest: Added Hall & Oates, Matisyahu, Meatloaf, and Jack’s Mannequin

– End of the Road Festival (UK): Added Joanna Newsom, Best Coast, and Lykke Li

— Movement: Paxahau Electronic Music Festival: Added Cassy, Guillaume & The Coutu Dumonts

— Rock am Ring im (Germany): Added Deadmau5, Pete Yorn, Frank Turner, Chapel Club, and Dredg

— Summer Camp: Added Huey Lewis, Bruce Hornsby & The Noisemakers, SOJA, and The New Mastersounds

— ATP’s Nightmare Before Christmas (UK): Added Flying Lotus, No Age, Marnie Stern, Archers of Loaf, and Omar Souleyman

— Bestival (UK): Added PJ Harvey, Fatboy Slim, Public Enemy, The Drums, Pendulum, Chromeo, and Big Audio Dynamite

— Sweetlife Festival: Official lineup announced, includes The Strokes, Ra Ra Riot, Cold War Kids, Lupe Fiasco, Girl Talk, and Crystal Castles

— Heavy T.O. (Canada): Official lineup announced, includes Rob Zombie, Anthrax, Motorhead, Megadeth, Billy Talent, and As I Lay Dying

— Camp Bisco: Initial lineup announced, includes Disco Biscuits, Wiz Khalifa, Bassnectar, Pretty Lights, Death From Above 1979, Lotus, Ghostland Observatory, STS9, and Beats Antique

– Reading and Leeds (UK): Official lineup announced, includes Muse, The Strokes, Jane’s Addiction, The National, and My Chemical Romance, as well as Deftones, Interpol, Elbow, Jimmy Eat World, Odd Future, Crystal Castles, and Two Door Cinema Club