Snider drove a 2-2 pitch from Jim Henderson (3-5) over center field for his second pinch-hit homer of the season.
In the NL West, the Los Angeles Dodgers widened their lead to 13.5 games with a 7-4 win over Colorado for their sixth straight victory.
Ricky Nolasco (12-9) allowed two runs in improving to 7-1 with a 2.27 ERA in 11 starts since coming to Los Angeles.
Carl Crawford singled in a pair of runs in the second and had three hits to make up for the absence of injured catalyst Yasiel Puig.
Atlanta’s lead in the NL East is even bigger than the Dodgers’ at 15 games after the Braves beat the Mets 3-1.
Braves starter Kris Medlen (12-12) allowed one run in seven innings while striking out nine. Atlanta have won 20 of their past 24 home games.
Kansas City’s Salvador Perez drove in Mike Moustakas with two outs in the eighth inning to lift the Royals to a 4-3 win over Seattle, after earlier blowing a three-run lead.
In other games, Toronto’s Edwin Encarnacion, Rajai Davis, Adam Lind and Moises Sierra all homered as the Blue Jays beat Arizona 10-4 while Washington’s Wilson Ramos hit a three-run homer and Corey Brown also went deep as the Nationals downed Philadelphia 9-6.
In New York, the Yankees were 6-4 winners over the White Sox, while in San Diego, the Padres edged the Giants 3-2.
Elsewhere, the Marlins routed the Chicago Cubs 6-2 and Minnesota defeated Houston 9-6 after Clete Thomas scored the go-ahead run on a wild pitch in the 12th inning.