After the only wet qualifying session of the year so far, characterised by varying levels of grip and a red flag that interrupted Q2 for more than an hour and a half, Ferrari driver Fernando Alonso claimed a dramatic first pole position for Pirelli's Cinturato Green intermediate tyre.

None of the drivers used their allocation of slick tyres in qualifying, instead just using the three sets of wets and four sets of intermediates available to them for Saturday and Sunday as fixed by the Sporting Regulations. An additional set of intermediates, available only when Friday's free practice is declared wet, was returned to Pirelli this morning before the final free practice session.

With light rain at the start of Q1, all the drivers went straight out on the Cinturato Green intermediate tyre to set a time early in the session in case conditions worsened. All 24 cars were running within the first couple of minutes, meaning that finding a clear lap became the key to a quick time, with the track changing second by second. Sauber was the only team to try slicks during a brief dry window, but with more rain falling, both cars reverted to intermediates.

Heavier rain in Q2 meant that the Cinturato Blue wet was the default option, although the Ferrari drivers started the session on the intermediate before an early switch to full wets. With conditions worsening, all the teams chose to run as much as possible during the session, hoping to find a brief window of clearer weather and traffic. With six minutes to go, the red flag came out because of torrential rain and the session was stopped. It re-started at 15:07 local time after conditions eased and track marshals swept away the worst of the standing water. Most drivers again used the full wet tyre, with only the two Saubers trying intermediates. Kamui Kobayashi then went back to full wets while Sergio Perez stuck with the intermediates, ending up 17th. As the track dried the times came down, with McLaren's Lewis Hamilton going quickest of all on the Cinturato Blue.

The majority of drivers in Q3 moved onto the Cinturato Green intermediates, with just three drivers starting the session on full wets (McLaren driver Lewis Hamilton, Lotus driver Kimi Raikkonen and Mercedes driver Michael Schumacher) before changing to the intermediates as well. As the track continued to dry, Alonso timed his lap to perfection and clinched pole in the final seconds.

The final free practice session was crucial this morning, as it was the only opportunity the teams have had to run on the slick tyres. Alonso went quickest thanks to a time of 1:32.167 on the P Zero Yellow soft: nearly 20 seconds faster than his pole time of 1:51.746.

The forecast for the race on Sunday is still uncertain, with even a possibility that all three patterns of tyre - wet, intermediate and slick - might be used. This makes it very hard for the teams to plan a strategy, but if conditions remain consistently wet, just one set of full wets could theoretically last for the whole race. If the drivers start the race on wet or intermediate tyres (as was the case at Silverstone last year) they are no longer obliged to use both slick compounds during the grand prix. It's more likely though that conditions will be mixed, which means that the strategy becomes more complex.

Paul Hembery: "A bit like the Canadian Grand Prix last year, we had a lengthy stoppage in qualifying at Silverstone followed by a very exciting finale that was well worth the wait. Although our full wet tyres disperse 60 litres of water per second, the quantity of standing water as well as the spray coming from the cars, made conditions simply too dangerous to continue in Q2. Mixed conditions throw up so many variables in terms of grip, so tomorrow's race will come down to which teams and drivers are able to read and forecast the conditions most accurately, despite the limited data they have accumulated so far. Establishing where the crossover point is was key to qualifying, with the intermediates proving to be fastest in the final session, and this is likely to be crucial again tomorrow."

Tyres used by the top ten qualifiers:

Alonso: Intermediate
Webber: Intermediate
Schumacher: Intermediate
Vettel: Intermediate
Massa: Intermediate
Raikkonen: Intermediate
Maldonado: Intermediate
Hamilton: Intermediate
Hulkenberg: Intermediate
Grosjean: No time set

Check out our Saturday gallery, here.