〜とあって

連休(れんきゅう)とあって、道路(どうろ)が混雑(こんざつ)しています。

Renkyū to atte, dōro ga konzatsu shite imasu.

With it being a long weekend, the roads are jammed.

とあって gives a special occasion as the reason, with the resulting scene after

優勝(ゆうしょう)がかかった試合(しあい)とあって、満員(まんいん)でした。

Yūshō ga kakatta shiai to atte, manin deshita.

With the title on the line, the place was packed.

Reporting uses it to explain crowds and other observable effects

自分(じぶん)のことには使(つか)いません。

Jibun no koto ni wa tsukaimasen.

It is not used about yourself.

Its stance is that of an outside observer; the subject is the scene