It appears that SmartThings did provide some alternate weather data when the WeatherUnderground API was deprecated 1/1/19. Those being
getTwcConditions() getTwcForecast() getTwcLocation() getTwcAlerts() getTwcAlertDetail()
That said, it will require a bit of work to support those in BigTalker2. The functions and returned data is not the same as the code currently expects. The future of Groovy code for SmartThings is concerning as well so I’m not sure it’s worth the effort to rework it to use the new API’s. They also post this note on each of these API calls which concerns me that these may not remain available as well: “If you are considering the development of an application that makes extensive use of weather data, you should consider gaining direct access to APIs from a weather data provider.”
More info on the weather issue: Weather API Changes
This is a change in the platform API that BigTalker (and many other apps) used to obtain the data needed for weather reports. Technically, SmartThings could write the same functions that were used with the Weather Underground integration and translate as needed to get the data to/from the new “The Weather Company” API and perhaps not break app code, but I doubt they will do that.