After any heavy downpours of rain we have, you are more likely to encounter a washout in a bunker. If so, how do I get out of it? 

Our local rules state that a bunker washout us an abnormal course condition. So Rule 16.1c cover this.

If your ball lands in a bunker, the nearest point of complete relief is outside the bunker. So, can I drop free of penalty outside the bunker?

 Good try! To obtain free relief from a washout in the bunker, you must determine the nearest point of complete relief IN the BUNKER, no nearer the hole and drop within one club length of that point in the bunker. If there is "no such nearest point of complete relief in the bunker", you then have to obtain relief "by using the point of maximum available relief in the bunker as the reference point".

In this image, both right and left hand golfers could obtain relief if your ball is at A. 

However, at point B, only right handers are affected by the washout (rule 16 says: “interference occurs when a ball lies in or touches the condition or when the condition interferes with the player’s stance or his intended area of swing”).

Bad luck Gary - there is no interference by the washout for left handers. Play it as it lies!

Now, is there any way I can drop out of this bunker when the washout causes interference? Yes -  rule 16.1c(2) goes on to say that in a bunker the player can lift the ball and drop the ball, under penalty of one stroke outside the bunker keeping the point where the ball lay directly between the hole and the spot on which the ball is dropped, with no limit to how far behind the bunker the ball may be dropped.

The same rule can be applied if your ball lies in temporary water in the bunker, which is also classified as ‘abnormal course conditions’!