Confused?

I got the blinking smiley face today and yesterday on clear blue ovulation test- so I SHOULD get the peak ovulation smiley tomorrow and the next day which is when I should ovulate. But what I don't get is the app is saying my most fertile days are tomorrow 27% the 30th 33% and the 31st 22%. If I ovulate on the 30th, shouldn't the 31st be blue as in a low percentage of conceiving? Or is it still a fertile period for 24 hours after your ovulate?