I had to book a redemption ticket from LA to London, but the only availability was an F ticket on BA from MIA to LHR.

So I'm going to fly paid Y or J on AA from LAX to MIA and then go on a separate ticket in F on the BA flight leaving at 20:40.

Obviously, the potential for an LAX-MIA delay is the big risk here.

I'm traveling in mid-June, and am debating between flying on the redeye (such that I land about 12 hours ahead of my flight to London) or one one of the first flights out of LA early in the morning, which give me a 4-6 hour buffer before my London flight if all goes to plan.

In the event of a delay, how easy would it be to get from the AA gate to the BA gate if I were to have hand luggage only? Are the gates in the same terminal/area, or do I have to go out and then go through security again?

I've never flown LAX-MIA -- is this a route that tends to get hit with summer thunderstorm delays, as often happens with CHI-NYC flights?

Any tips/advice appreciated.