The phrase "a powerful sign" is correct and usable in written English.
You can use it to describe something that indicates a strong or significant message or change.
Example: "The sudden increase in community engagement is a powerful sign of the growing interest in local issues."
Alternatives: "a strong indication" or "a significant signal".
For him, these worms are a powerful sign of hope.
King's tweet is a powerful sign of the times.
FitzGerald would have approved of the presence of the Queen and Prince Phillip as a powerful sign of normalisation between the two countries.
Jerry Fowler, president of the Save Darfur Coalition, praised the pending Rice nomination on Sunday, calling it a powerful sign of the new president's interest in the issue.
I'd argue instead that the homey conversation that permeates most gatherings of suburban mothers is a powerful sign of the success of the women's movement.
This would not only be a powerful sign of the durability of our transatlantic partnership, but also a message to the Iranian people.
Is there a more powerful sign of intent to make this a nation for all its people, or a better way of restoring income and employment in places where there is little of either?
"It would be a very powerful sign countries want to stick together in a monetary union," Mr. Constâncio said.
In Chinese astrology, the Tiger is a dynamic and powerful sign.
Rose, 31, shared plenty of snaps from the event on her Instagram page, including a selfie in front of the crowd, a snap of one woman's powerful sign and a photo of herself holding a sign that read, "Strippers have feelings too!" .
Nationalists who vote for Sinn Féin in Northern Ireland may regard a McGuinness presidency as another powerful sign that they are reunited with the rest of the Irish nation; but a President McGuinness or any other president after 27 October will still be presiding over partition, whatever they might tell their core supporters.
