Well I have considered trying watching the sky for bird patterns...

Well I have considered trying watching the sky for bird patterns (Ornithomancy ) at times, or even following the ancient Romans and Babylonians by studying the entrails of sacrificial animals (haruspicy) on other occasions. But vmp is closer to the mark with his more serious response I believe.

However, if I'm half-hearted about a buy at a certain price, and if I notice from the trade history and latest/expected news that it's tending to be volatile with a pattern, I'll sometimes put a lowish bid into the queue and just leave it there for a few days. If it comes off and you didn't miss the boat, it feels like a bargain (like my first RDN purchase recently). If it's a sale I'm half hearted about, I sometimes use the same strategy in reverse and place an optimistically high sale price in the queue (which luckily worked with a small LTR parcel I sold prior to the slump). Good luck with your RDN at 3.9c (or maybe even slightly lower?) but unless it involves a heap of them, why fret about a few pips?