Today's recently ended track action at the Gilles Villeneuve circuit in Montreal produced more questions than answers in the build-up to the 53rd Canadian Grand Prix.

The main reason was the changing weather conditions that saw rapid switches from sun to rain and even hail. There were about thirty minutes at the start of the second free practice session where it was possible to run consistently with dry weather tyres but before and after that, the rain got in the way.

The quickest time overall was set by Fernando Alonso (Aston Martin) in FP2 in 1'15"810, after Lando Norris (McLaren) headed the field in the first session with a time of 1'24"435.

The track was very wet for the start of the first session, to the extent that the pit lane light was kept on red for the first 21 minutes. Once it turned green, nine drivers used a set of Extreme Wet, although without completing a timed lap. The switch to Intermediates saw a few drivers do a run on the green-banded tyres. However, it was only towards the end, following a five minute stoppage required to remove Guanyu Zhou's Sauber, which had crashed into the barriers, that slicks were finally viable with all drivers doing a run on the C5, the softest compound available in Montreal.

Initially, the track was considered to be dry at the start of the second session, even though rain had fallen quite heavily in the hour leading up to it and there were even a few drops still falling. All the drivers made the most of it to get in some mileage, most of them - 16 out of 20 - opting for the Soft. The exceptions were the Ferrari and McLaren drivers, who concentrated on the Medium. Then, yet another shower halted the action on track, while towards the end of the session all the drivers, with the exception of Max Verstappen (Red Bull) stuck in the garage with a technical problem, went back out on Intermediates even though the track was drying out at various points.

Simone Berra - Chief Engineer: "It's very difficult to draw any conclusions from today, which saw the weather alternate between sunshine and showers. Track conditions never got close to optimal, as seen from the fact that lap times on the slicks were a very long way off, around four seconds in fact, of the average simulation times received from the teams prior to this North American trip. That still leaves two main unknown factors, namely how the tyres will suit the new track surface, and so far today we have seen very low levels of grip, so it is logical to expect a marked evolution if the cars can run consistently on a dry track, and secondly the level of graining. We have been able to gather some slightly more solid data on the crossover point from intermediate tyres to slicks, confirmed at around 112% of a dry lap time.

"Clearly, uncertainty surrounding the weather for the rest of the weekend will be a major consideration: for tomorrow, Meteo France is currently saying there is an 80% probability of rain for qualifying, while the figure is lower for the race, but we know that the situation can change rapidly here."

Check out our Friday gallery from Montreal here.