The main reason is that a Google search for "WeatherBomb" would show results for actual weather bombs hitting the UK and New Zealand and bombings around the world. This isn't good for new users finding the app. A few new users said "change the name, get more users."
I know many seasoned users liked the name "WeatherBomb". A pilot said he liked the name even though he couldn't say it on a plane.
I stayed awake many nights thinking about new names. Flowx is a combination of "flow" which is related to the swiping (and in the near future, streamlines) and "wx" is the Morse code abbreviation for weather.
Flowx ticks many boxes. It's unique, distinctive and short, for those who write it every day.
The pronunciation of "Flowx" is floh-eks.