In spite of everything I've been saying for the last ten years and in spite of today's Guardian and in spite of the the blog on the previous page, here is a description of what a fronted adverbial is:
Luckily, the weather was good.
('Luckily' is what's known as an 'adverb' here.)
In the morning, the weather was good.
('In the morning', is what's known as an 'adverbial phrase' here.)
When I was out, the weather was good.
('When I was out', is what's known as an 'adverbial phrase' here.)
These 'adverbials' are 'fronted' because they are 'in front of' the 'main clause' , 'the weather was good'.
Everybody who speaks English uses these constructions when they speak and write. We often do it as a way of emphasising something or selecting something for interest.
We also put 'adverbials' in the middle of sentences and at the end of sentences. We do this to emphasise or make things interesting too. But it all depends on who we are, who we're talking to or writing for, or what 'genre' we are in: eg a newspaper or a TV script or talking on a chat show, or with our friends or wherever.
In German, this matter of putting things 'in front of' the main clause results in the speaker or writer having to do something with the structure of the main clause: they have to switch it round so that the 'main verb' comes in front of the 'subject'. We do this sometimes in poetry. It usually sounds a bit antiquated or poetic or bit like a rhetorical speech eg
'On the river bank, lay the two dogs.'
The term 'fronted adverbial' poses two problems. The people who've prioritised it as a 'good' language structure to use in writing, haven't said why it's better than a middle or rear adverbial or even mentioned that middle or rear adverbials exist.
Secondly they haven't said whether 'fronted adjectivals' exist eg
'Pink toed, his feet shone in the light.'
Clearly, 'pink toed' (or pink-toed', as you wish) is to do with his feet. It's adjectival.
This is an example of how when you prod and poke this terminology it keeps collapsing.
Enjoy.
