Originally Posted by RonBee

Usehowever if you want to contradict or contrast with what was said before. Example:

• He makes a lot of money. However, he is very stingy.

Use provided to indicate a contingency or condition.

• Provided that there is enough money, we will eat out Thursday night.

Use in the event of to indicate a contingency or condition. Example:

• In the event of rain we will stay inside.

Whether is often used to indicate a contingency or possibility. Example:

• I don't know whether he has left the building or not.

:)