It might be hard to tell in this photo, but the Turkish flag was flying and the symbol of crescent and star were also on the balloons.
I tried to find out online if today was a special Turkish holiday, but found nothing, so it must be something within the family. I thought about sticking around and asking the next person who passed by, but nixed that idea when someone cracked open the door after I had taken 2 photos. Oops.
I'll try to ask some of my Turkish classmates on Tuesday when I see them again. (And the Russian word for holiday--праздник--keeps coming to mind.)