The "cozy factor" of a post-blizzard concert is nice but only goes so far - and didn't have to with the baroque orchestra Tempesta di Mare.

Audiences were made to feel a tad heroic for trudging through Society Hill for Sunday's second installment of Tempesta's ongoing examination of Bach's Brandenburg Concertos at Old St. Joseph's Church. But what made the concert worth the slipping and sliding - and an encouraging development for Philadelphia's early-music community - was better-than-usual preparation plus well-channeled energy, perhaps pent up from the group's canceled Saturday concert in Chestnut Hill. Whatever the weather implications of its name, Tempesta di Mare usually goes on no matter what, but on Saturday, faced questionable post-concert transportation options.

Not one just to play Bach's masterpieces, Tempesta in its Brandenburg series contextualizes the music within like-minded works from Bach's time - a great practice with any repertoire. Even minor figures show how differently creative minds reflected their time, even though, however pleasant, these particular Bach contemporaries were at best charming. In fact, Bach's already considerable stature, as represented by Brandenburg Concerto No. 5, was emphasized in the program's context. What amazingly lean, dense music it is, with many potentially ill-fitting elements incorporated into logic that lets everything be all it can be. The first movement's famously long harpsichord episode seemed wildly extravagant - and was played by Adam Pearl with virtuosity and daringly original tempo changes that felt fresh and right.

Besides being fully polished, the Bach performance had an exceptional sense of chamber-music interplay between violinist Emlyn Ngai and flutist Gwyn Roberts (Tempesta cofounder). Both outdid themselves, Roberts playing with great security (especially in Graupner's Suite in F) and Ngai handling the dance rhythms not as a restrictive means of order, but more lightly, as an emphatic highlight in a continuous musical line, particularly in Pachelbel's Partie a 4. Fasch's sleepy Concerto in D minor might at least have been a good showcase for lutenist Richard Stone (also a Tempesta cofounder) had his demure instrument not been swamped by a larger instrumental sound.

Still, the concert offered a glimpse of what this community is missing. If you squinted a bit, you could imagine yourself in New York City's Corpus Christi Church, home of the Music Before 1800 series - one of that city's great musical assets and one in which an enterprising New York-caliber concert like this would be just one in a wide range of ensembles that encompass great musical centuries rarely represented in Philadelphia.