The Spanish Grand Prix, the first of the European races in the 2015 Formula One World Championship, got underway this morning in beautiful Barcelona with the first of the free practice sessions. The event’s Circuit de Barcelona-Catalunya home is a familiar one for all the teams, as it was where two of the pre-season winter tests were held—but now the weather is much warmer.

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Weather is always a major unknown at the Spanish Grand Prix. In the past we’ve seen some very hot conditions but this isn’t always guaranteed. The current weather forecast for Sunday’s race is dry and warm conditions, with a peak temperature of 77 degrees F (25 degrees C). There could be some overcast intervals leading up to the race, but it should remain bright and clear on the day.

The Catalunya circuit’s rough surface, high-speed corners and warm ambient temperatures will put a lot of stress on the tires. As a result, Pirelli has nominated its two hardest compounds, hard and medium, for the race. Another factor to watch out for will be potential car upgrades, as the start of the European leg of the F1 calendar is traditionally where teams first make changes to their cars.

At the time of writing, Mercedes AMG’s Nico Rosberg, still committed to the title this season, was fastest round the Catalunya circuit, with a best lap in 1.26.828. Behind the German came his Mercedes teammate Lewis Hamilton (1.26.898). Next up were the two Ferrari men Sebastian Vettel (1.27.806) and Kimi Räikkönen (1.27.832).

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Meanwhile, Fernando Alonso, who’s driving at his home event, was all the way back at 15th. McLaren’s ongoing woes with its Honda-powered car means Alonso’s performance this season hasn’t been so poor since 2001, when he debuted with Minardi. Hopefully we’ll start to see things turn around soon. His teammate Jenson Button was one spot further back at the end of the first practice session.

Going into tomorrow’s qualifying session and Sunday’s race, Hamilton leads the 2015 Drivers’ Championship with 93 points, followed by Rosberg with 66 points and Vettel with 65 points. In the Constructors’ Championship, Mercedes is on top with 159 points followed by Ferrari with 107 points and Williams with 61 points.

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