yuki ga ryokou no syougai ni natta.

A helpful breakdown is:

• 雪 = snow
• が = marks snow as the thing being talked about grammatically
• 旅行 = trip / travel
• の = links 旅行 and 障害
• 障害 = obstacle / hindrance
• に = marks the result of a change
• なった = became

So the sentence is roughly:

Snow became an obstacle to the trip.

A very literal gloss would be:

As for what happened, snow became a travel obstacle.

が marks 雪 as the grammatical subject: the thing that became something.

So in:

雪が障害になった

the snow is the thing that turned into / functioned as an obstacle.

If you changed it to は, the nuance would shift:

• 雪が旅行の障害になった = Snow is what became the obstacle.
• 雪は旅行の障害になった = As for snow, it became an obstacle to the trip.

So が sounds more neutral and event-focused here.

旅行の障害 means an obstacle to the trip or a hindrance to traveling.

The particle の connects the two nouns. It often works like of, but in English the best translation depends on context.

Here, 旅行の障害 is not really the trip's obstacle in a possessive sense. It means:

• an obstacle for the trip
• something that interferes with the trip

So の is showing a relationship between travel/trip and obstacle.

Noun + に なる means to become X.

So:

• 障害になる = to become an obstacle
• 障害になった = became an obstacle

This is a very common grammar pattern:

• 先生になる = become a teacher
• 春になる = become spring
• 問題になる = become a problem

In this sentence, snow changed from just being a condition to functioning as an obstacle to the trip.

Because the sentence is using the pattern X に なる (become X), not simply X だ (is X).

Compare:

• 雪は障害だった = The snow was an obstacle.
• 雪が障害になった = The snow became an obstacle.

The second one emphasizes a change or development. It suggests that the snow came to interfere with the trip.

No. 障害 can mean several related things depending on context, such as:

• obstacle
• hindrance
• impairment
• disability

In this sentence, because it is about snow and travel, the natural meaning is obstacle or hindrance.

This is important because in other contexts 障害 may refer to disability, as in words like 身体障害.

Yes, it is grammatical and understandable.

It is a bit formal or written in tone because 障害 is a somewhat formal word. In everyday conversation, people might say something more natural like:

• 雪で旅行に行けなくなった。
  We couldn't go on the trip because of the snow.

• 雪が旅行のじゃまになった。
  The snow got in the way of the trip.

So the original sentence is fine, but it sounds a little more formal or explanatory.

Because 旅行 is directly modifying 障害 through の.

In other words, 旅行の障害 is one noun phrase:

• 旅行
  • の
    • 障害

So 旅行 is not acting separately as the subject or object of the sentence. It is part of the larger expression obstacle to the trip.

It could be understood either way, but in this sentence a trip is probably the most natural translation.

That is because 旅行 often refers to a specific trip or journey in context. So:

• 旅行の障害 = an obstacle to the trip

If the broader context were more general, it could also mean an obstacle to travel.

Japanese often leaves that level of specificity to context.

Yes, that is close to the literal structure, but it sounds unnatural in English.

A more natural English translation would be:

• Snow became an obstacle to the trip.
• The snow interfered with the trip.
• Snow was a hindrance to the trip.

So the literal structure is useful for understanding the Japanese grammar, but the natural English translation should be smoother.

If you said:

雪は旅行の障害になった。

it would put more topical emphasis on snow.

Possible nuance:

• 雪が旅行の障害になった。
  Snow became the obstacle.
  This sounds like identifying what caused the problem.

• 雪は旅行の障害になった。
  As for snow, it became an obstacle to the trip.
  This sounds a bit more contrastive or topic-oriented.

In many contexts, both are possible, but が fits well when simply describing what happened.

They are:

• 雪 = ゆき
• 旅行 = りょこう
• 障害 = しょうがい
• なった = from なる

So the full sentence is read:

ゆき が りょこう の しょうがい に なった。