Not "portable", but I read there is a Garmin weather subscription available for those lucky enough to have G500/600 with the satellite receiver..
https://fly.garmin.com/fly-garmin/gfds-weather/
Not sure how much it costs.. probably $$$
Edit: If i'd bothered to read the page, it has the subscription costs towards the bottom at the side.
I use an app called "Rain?" on my iPad to get the BOM weather radars.