meaning of "[subject] [negated verb], as [clause]"

Consider the following statement:

I will not carry an umbrella tomorrow, as I do on rainy days.

It might seem clear to us that the meaning is that the speaker intends not to carry an umbrella, though carrying an umbrella is usual on rainy days.

The reason this meaning is clear may owe in part to our understanding of the ontological relationship between an expectation of rain and carrying an umbrella.
Suppose such understanding were unavailable to us.

For example, imagine a sentence of the following form:

I will not carry an umburgle tomorrow, as I do on strainy days.

Suppose the meanings of the words umburgle and strainy are understood by others, but not by us, and we are to decide between the following meanings:

1. The speaker intends not to carry an umburgle, though carrying one is usual of strainy days.
2. The speaker intends not to carry an umburgle, because carrying one is unusual on strainy days.

Does English grammar (i.e. syntax) give any single interpretation of this sentence, with respect to the above distinction, or is it essentially ambiguous?