Bandoneon player Raúl Jaurena, right, performs in a concert to honor Pope Francis at the Kennedy Center. (Scott Suchman/National Symphony Orchestra)

There are a couple of ways to make a classical concert feel like a particularly special event. One is to make a big out-of-the-box celebration. Another is to perform in extenuating circumstances — during a snowstorm, say, when only part of the audience shows up.

The Kennedy Center’s free concert honoring Pope Francis on Wednesday night — with the National Symphony Orchestra, singers from the Washington National Opera and an assortment of other gifted musicians — was conceived as the former but ended up feeling more like the latter, since the threat of horrible traffic that kept everyone out of the city center all day also meant the hall was only partly filled.

The pope was not in attendance, but Cardinal Donald W. Wuerl, the archbishop of Washington, put in a gracious appearance after what must have been an exhausting day. He conveyed a blessing from the pope and, perhaps equally satisfyingly, a brief sense of what it was like to spend the day with him, including the vaunted spontaneity that led to the pope tacking on two unscheduled stops — to Saint John Paul II Seminary and the Little Sisters of the Poor — after the day’s official activities.

The concert was put together in some haste, when the Kennedy Center’s president, Deborah Rutter, laudably decided it was fitting for the nation’s performing arts center to commemorate this historic visit. It is therefore no surprise that it was a bit of a muddle — although it did present some interesting opportunities. Evan Rogister, who is conducting the WNO’s “Carmen,” had never appeared with the NSO before. Nor had Ariana Wehr, an incoming member of WNO’s Domingo-Cafritz program, or Clémentine Margaine, currently singing the title role in “Carmen.” Given that the symphony is looking for a new leader, it was an opportune time for Rogister to meet its members, although it sounded as if the hall’s acoustics were giving him trouble in Holst’s “Venus, the bringer of peace” from “The Planets,” which was a little muddy. Britten’s adaptation of part of the second movement of Mahler’s Symphony No. 3, “What the Wild Flowers Tell Me,” offered individual players a chance to shine.

Wehr, who is off to a nice start in Washington with her company debut as Frasquita last week, showed a colorful soprano, a little muted in the opening “Exsultate, jubilate” (Mozart), but bright and confident, with impressively fluid coloratura, in the famous “Alleluia” from the same piece that concluded the program. Margaine was more reserved: She started Franck’s “Panis Angelicus” with a huge and beautiful sound, but then didn’t do anything with it. Thus, a performance that promised in the first few bars to be breathtaking ended up falling curiously flat, marred by the habit she also showed in last week’s “Carmen” of excessive slurring, and a tendency to sound as if she were singing through a mouthful of marbles.

The program included two speakers in brief cameos: The 17-year-old poet Hannah Smallwood recited the Robert Hayden poem “Monet’s Waterlilies,” and actress Eva Longoria gave a brief but touching recitation of Eunice Kennedy Shriver’s exhortation to Special Olympians in 1987, which Longoria prefaced with the information that her older sister is developmentally disabled and that her family has been intimately involved with this particular cause.

The audience favorites were the entrants from the Spanish-speaking world. Members of the National Youth Orchestra of Uruguay and the bandoneon player Raúl Jaurena offered a bracing account of Piazzolla’s “Libertango,” an arrangement of which the NSO played with the percussionist Martin Grubinger in its opening gala on Sunday. And 10-year-old jazz pianist José André Montaño, blind and with a halting, uncertain gait that requires someone to help him on and off stage, came out and dazzled in authoritative performances of “Imagine” and “Somewhere Over the Rainbow.”

“I have a message for the children,” he began in his high-pitched child’s voice, proceeding, over unscripted piano playing, to say a few words about hope, exhorting everyone to remember that “life is a gift” — a message that skirted kitsch by virtue of its purity and brought the moved audience to its feet as the young pianist made his way off stage.