One conceivable scenario is that they expected to land on 27 and set the minimum for the ILS. Then something occured which distracted them. A medical emergency has been suggested in earlier posts.
They decide to expedite by landing on 09 but fail to brief properly. It is no big deal they think, with clear skies, homebase, and Fifi flies herself anyway doesn't she? They forget to set the QNH. Bit hot and high so they have trouble stabilising the approach with the tailwind. But it is all in a good cause, getting the sick passenger on the ground asap.
The early morning fog combined with the sun makes it difficult to see anything. They sail through the minimum and very low above ground realise their mistake and attempt a go-around which as jshg has explained can be tricky in this scenario. The plane impacts the ground and breaks up in the fashion Bearfoil so vividly describes.
Be interesting to see how much of this speculation turns out be correct once we get the report.