Victoria G. answered 06/18/19
Write and Publish Your Book! Award-Winning Author Offers Coaching
You are wise to avoid the use of the word "suddenly", or the phrase, "all of a sudden", as nothing really happens "suddenly". We simply become aware of whatever is and has been happening in a particular moment of time. Editors do NOT like the word "suddenly" in manuscripts, and consider it amateurish (as I still must remind myself!) :)
You might want to think of concepts such as:
"Before Jezebel placed her first item on the checkout counter, enormous, jagged chunks of the ceiling crashed onto her shopping cart and smashed it flat before her."
"In that same moment, a lanky figure darted out from the shadows and shoved Cindy out of the car's path."
It is clear both these things happened "suddenly" from the character's point of view, but obviously something had been in the works beforehand. Yet, it still comes as a surprise to the reader as well. Most importantly, we did not use the forbidden word(s) :).
There are many other examples and strategies, but I hope these have helped you for the moment.
Happy writing!