Bundle up and head to McMenamins Old St. Francis School in Bend Saturday to sample big and bold beers at the second annual High Gravity Extravaganza.

Out of a desire to bring something different to the Central Oregon beer scene, Jared Prince, McMenamins’ property manager, and brewmaster Mike “Curly” White teamed up to put on the first High Desert Extravaganza in 2014. The idea was to celebrate Central Oregon winters: to be out in the snow, cozied up around fire pits with beers strong enough to stave off the cold. Prince and White wanted to feature different styles of high-gravity beers from other McMenamins breweries as well as other Central Oregon breweries, and, most importantly, “we wanted to have fun with beer,” Prince said. “That’s it.”

And just what makes a high-gravity beer high gravity?

“Gravity is a scientific measurement of the density of liquid,” said White. (Note: When talking about alcoholic beverages, “gravity” refers to specific gravity, or the relative density of an ingredient to water. Not Isaac Newton’s gravity or Sandra Bullock’s “Gravity.”)

Beer is made from wort, a sugary liquid produced by the grains used to make beer. In beer, gravity is the density of the wort compared to water. According to White, there are two types of gravity: original gravity (the gravity of the wort before fermentation) and terminal gravity (the gravity of the beer).

During fermentation, the sugars from the wort are eaten by yeast and turn into alcohol, and at the end of the brewing process, brewers use terminal gravity to determine the alcohol content of their beer. Typically, a greater difference between original and terminal gravity produces a stronger beer, and the higher the original gravity of the wort the more alcohol the beer will contain.

High-gravity beers are sure to pack a punch when it comes to flavor, which is exactly what White wants. More ingredients are used to make high-gravity beers, which produces a fuller, bolder, more complex flavor, White said. High-gravity beers are made with more malts (grains used to make alcohol), and more malts make more sugars with the potential to create more alcohol during fermentation. So the High Gravity Extravaganza’s motto — “Go Big or Go Home” — isn’t just about going big with alcohol content, it’s about flavor and complexity.

“High gravity encompasses all that,” White said.

There are many different styles of high gravity beers — pale ales, porters, stouts, etc. — and brewers get to make whatever they want for Saturday’s event.

“Brewers are like artists. They get to have their creative genius and have fun with it,” Prince said.

All beers poured at the event were brewed specifically for it, and the brewers will be the ones pouring. White’s special beer for the High Gravity Extravaganza is a Belgian Dark Strong Ale that he named Shadow of the Dark Belgian Strong. He says it’s fruity, a little “bubblegummy,” and has the second highest gravity of any beer ever made at McMenamins in Bend, with an alcohol content of around 9.2-9.4 percent. White also reports that the coppery red ale has a stronger malt flavor than hops flavor.

A total of 22 breweries are attending the High Gravity Extravaganza, which is six more than last year. Ten McMenamins breweries will return to the event, where they’ll be accompanied by locals Bend Brewing, Riverbend, Sunriver, Three Creeks, Solstice, GoodLife, Wild Ride, Crux, Worthy, Silver Moon, Boneyard and Deschutes.

To highlight Central Oregon’s beautiful winter, the extravaganza will be an indoor/outdoor event, with plenty of fire pits to huddle around outside, as well as live music inside by local jam band Mark Ransom & The Mostest (3-6 p.m.) and Seattle funk band Down North (7-10 p.m.), plus plenty of beer-oriented food to accompany the high-gravity brews.

— Reporter: 541-383-0350, kmccool@bendbulletin.com