This notably resulted in postponement of the 2009 MotoGP race from Sunday to Monday.
But following a recent wet night test at the circuit by Loris Capirossi and Franco Uncini (there are conflicting reports about the vehicle used) it was decided that track action could potentially continue.
However, no final decision will be taken until the grand prix riders have tried such conditions for themselves.
As such, should rain arrive during opening practice this (Thursday) evening, as forecasts suggest, riders will be expected to head out on wet tyres and then give their opinions in a special meeting of the Safety Commission.
If wet weather only arrives after the single MotoGP Thursday session (FP1, 19:55-20:40), a new wet practice session will be arranged at the very end of Thursday night.
If there is no rain at all tonight, further arrangements will made for evaluating such conditions on Friday.
Wet riding will apply to all classes, with Moto2 and Moto3 supplier Dunlop now joining Michelin in bringing rain tyres for this weekend.
When questioned on Wednesday, some MotoGP riders were more concerned about a lack of grip in the wet – due to sand blown onto the circuit – than visibility problems from floodlights reflecting off the rain and spray.