"in a worst case" is correct and usable in written English.
Example: In a worst case, the company could be facing bankruptcy if the appropriate action is not taken soon.
Or in a worst case scenario, they stop talking to you altogether".
Good, but do either realise what may be needed in a worst case?
That would mean litigation, which would harm bank profits, and in a worst case, risk another economywide disruption.
"The money was going to last me a year in a worst case scenario," he says.
In a worst case scenario, Russia could punish Europe buy tightening fuel supplies.
In a worst case scenario, people might even be in physical danger from a systemic outage.
In a worst-case scenario, the spiral unravels.
In a worst-case scenario, our car could have exploded".
In a worst-case scenario, both countries have nuclear weapons.
Leave town In a worst-case scenario, flee.
Optimal input design for system identification with quantized sensors is tackled in a worst-case setting.
