If you don't know what a TRW is, then I suspect you don't fly airplanes, or if you do, you don't check the weather.
Dunno, i fly for the last 24 years which is not all that long considering i have another 29 years until retirement, but over here we use ICAO and JAR abbreviations.
Oh, so i saw the posts above, TS for thunderstorm, RA for rain, SH for showers and it all can be combined.