Two ways I know...
- Davis stations that upload to Weatherlink.com can add Alexa skill.
- Any station that uploads to Ambientweather.net can add Alexa skill. Ambientweather.net is not limited to only Ambient stations. If you have a Meteobridge, and you add the Ambientweather.net license, then any Meteobridge compatible station can upload to Ambientweather.net, thereby gaining the Alexa skill. My favorite Meteobridge at the moment is the Raspberry Pi version, because of ease to set up, cost, and performance and features.