The Ferrari driver was quickest in the opening session and finished right behind pacesetter Sebastian Vettel's Red Bull in the afternoon.
Alonso reckons his car will be competitive at Barcelona, but he is aware that he needs to enjoy a trouble-free grand prix to have a chance of a strong result.
"I think there is still a long way until qualifying and unfortunately we missed the first session because of the rain," said Alonso. "It was the same for everybody but it was very useful information that we didn't get today.
"The car seems to be competitive, in the long runs as well, so it's a positive start.
"But we've had many Fridays with positive starts and then we see in qualifying that the Mercedes flies or that the Red Bull is in front of everybody. So we need to remain calm and analyse the information."
The Spaniard, who has not won his home race since the 2006 season, admitted victory at Barcelona would be a dream for him, although he concedes it will be very hard to realise it.
"It's still a dream," he said. "It's something that it's extremely difficult to get, not just in front of your home fans. You need many factors to come together to win on Sunday, so let's start with qualifying tomorrow.
"We know how important it is to start from the first two rows here in Barcelona. Maybe we are in the group of the leaders, but you can be first or you can be eighth with two or three tenths."