Lowe (1-1) gave up three runs on seven hits in six innings. He threw 115 pitches and struck out two while walking three, having a little trouble with his command in the final few innings.
"We couldn't get much going," said manager Bobby Cox. "[Lowe] kept us right there at three runs. We've got to be able to score that many once in a while."
The Braves finished with two runs on six hits, all of which came in the first four innings. They didn't get a hit after Matt Diaz's two-run homer in the fourth inning. Atlanta had only three baserunners in the final 5 1/3 innings.
Overall, the Braves left four on base and went just 1-for-5 with runners in scoring position.
"We never got anything real big going," Cox said.
Lowe hasn't had good luck with the Nationals and the weather this season. Earlier this year he threw only three innings in his first start for the Braves because of a two-hour, two-minute rain delay in the fourth inning of the April 10 game against Washington in Atlanta.
This time he went up against right-hander Jordan Zimmermann (1-0), who was making his big league debut. The rookie needed only 72 pitches to get through his six-inning stint, and threw 51 strikes while giving up two runs on six hits.
"He did a good job," said Chipper Jones. "I think everyone was pretty impressed. He's got a bright future."
This wasn't an easy night to pitch or play in. The temperature was 58 degrees with some wind when the game started, and it just got colder as the night went on.
"It was a cruddy night, terrible conditions to play in," Jones said. "It was gross out there."
The Braves had chances to take command early but couldn't convert. Casey Kotchman doubled off Zimmermann to start the second but was thrown out at third trying to advance on a pitch that momentarily bounced away from catcher Jesus Flores. Diaz doubled moments later, but he was stranded when Jordan Schafer flew out to end the inning.
"We just didn't get the job done tonight," Schafer said. "[Lowe] threw well, and when our starters throw well, we need to get wins."
Atlanta threatened again in the third, putting two on with one out before Yunel Escobar hit a soft grounder that Washington shortstop Alberto Gonzalez grabbed and quickly turned into a double play.
The Braves took the lead in the fourth when Diaz blasted his two-run homer to left. Jones started the inning with a triple to right, and he scored on Diaz's homer, which came on an 0-2 pitch with two outs, really the only mistake Zimmermann made in his debut.
But the Nationals tied the game in the bottom of the fourth on an Elijah Dukes RBI single and a Flores sacrifice fly. It stayed that way until Washington pushed across the tie-breaking run in the sixth. Flores gave the Nationals the 3-2 lead with his RBI single to left with one out.
After O'Flaherty took over and threw a perfect seventh, Soriano got into some trouble in the eighth. He gave up a double, hit one batter and walked another to load the bases with one out. But he bounced back to strike out Gonzalez and pinch-hitter Ronnie Belliard to end the threat.
Kotchman walked with one out in the ninth against Nationals closer Joel Hanrahan, but the Braves couldn't do anything else, as Washington snapped its three-game losing streak to win for the second time this season. It also ended a four-game winning streak for the Braves against the Nationals.