GRAMMAR DETAIL

とあって

given that

Explains that a noteworthy circumstance has produced a result appropriate to it.

Examples

人気作家の講演とあって、会場は早くから満席だった。

Given that it was a lecture by a popular author, the venue was full from early on.

休日とあって、店は朝から混んでいた。

Since it was a holiday, the store had been crowded since morning.

Structure: Attach とあって to a noteworthy circumstance to explain that it accounts for the following outcome.
Basic usage: 休日とあって、店は朝から混んでいた。 means that the shop was crowded from the morning onward because it was a holiday.

Distinction from the condition in とあれば
- 休日とあって gives the actual fact of a holiday as the reason. 休日とあれば presents a holiday as a condition for what someone would do or what would happen.