from 12 PM onward/on

[Odessa Dawn]

I have to have an appointment at the doctor's in the morning. Driving from 12 PM onward/on means that I will stuck in traffic jam.

This is in case there is a national vacation. What should come after 12 PM?

 

[emsr2d2]

I [STRIKE]have to[/STRIKE] have an appointment at the doctor's in the morning. Driving from 12 PM onward/on means that I will be/get stuck in ​a traffic jam.

This is [STRIKE]in case[/STRIKE] because there is a national vacation. What should come after 12 PM?

I would change the whole thing to "If I'm on the road around noon, I'm likely to get stuck in traffic."

 

[Odessa Dawn]

We only just started the new academic year. "in case" here means "when".

 

[SoothingDave]

I would change the whole thing to "If I'm on the road around noon, I'm likely to get stuck in traffic."

I think he means any time after noon.

 

[emsr2d2]

In that case, I would probably say "If I don't get on the road by noon, I'm likely to get stuck in traffic".