Portuguese phrases without verb

[José Catarino]

I am studying (apparently) non-head structures as (1) or (2), which are well
formed in Portuguese:
(1) Chuva, só no sábado.
(Name, adverb, preposition+det, name)
'Rain, only Saturday'
(2) Casamento, só no Verão.
'Marriage, only at Summer'
These phrases doesn't seems to result of ellipsis of the verb and subject.
I am exploring the hypothesis that they are licensed by some properties of
the name in topic and the syntactic structure, composed only by topic and
focus.
I would like to put some questions:
1. This hypothesis is  fully compatible with the HPSG's grammar?
2. The structures like (1) or (2) are possible in English?


If anybody knows of some HPSG works on this phrases, please let me know.

Thanks in advance,
José Cipriano Catarino