It could be, but like the verb holler, it would be colloquial and rarely seen.
"He ignored the hollered warnings and continued across the mine field."
To holler is a colloquial verb meaning to yell or shout.
He hollered for help when he got lost in the woods.
holler means scream loudly. Example: he Hollered after his work.
whisper
hollered
No... the proper way of saying hollered is saying that you shouted a bit longer than a shout. Announcing means that you just project your voice over a crowd and tell some news or even a speech. Therefore, hollered and announced do not match definitions.
The past tense is hollered.
A girl that is hollered back by a guy.
The traffic cop hollered "Stop!".
The boy hollered "dong!", and ran down the street.
screamed harangued hollered shouted
Shouted, hollered, screamed, howled, wailed, cried out, called out
"Move that scow, you scurvy dog!", hollered the Captain to the pirate. What sort of scow did you say that was?