Yell Silently Meaning

(idiomatic) To think very strong thoughts that one wishes to yell out loud but does not.

Example: 1964. Isaac Asimov, The Rest of the Robots, Doubleday, page 341:
  He yelled silently at R. Daneel: Machine!
1988. Craig Thomas, Winter Hawk, Morrow, page 373:
  Shut up, he yelled silently as the woman cried out in pain and terror in the cabin behind him.
2002. Elizabeth Lowell, Eden Burning, HarperCollins, page 365:
  Hurry, he yelled silently to the pilot. Hurry!