Through MeteoIO, it is possible to force Snowpack with data that has not been measured locally. The forcings are then extracted for example from gridded data (such as the outputs of weather forecasting models or reanalysis models) or by spatially interpolating stations' data to the point of interest. For the data extraction or interpolation, please refer to MeteoIO's documentation section "Spatial resampling" (see for example the current stable release documentation).
The SLOPE_FROM_SNO configuration key in the [Input] section controls whether slope angle and azimuth are taken from the sno file or from the meteorological forcings (in this case, automatically extracted from either the gridded data or from the DEM used for the spatial interpolations). Please note that this won't change the meteorological forcings (they are always only valid for their associated coordinates on flat field) but will allow Snowpack to reproject the precipitation and radiation fields on the slope (angle and azimuth) of your choice.
When relying on spatially interpolated values, it is often necessary to first run Snowpack at the real forcing locations in order to generate easier to interpolate fields (such as ISWR, ILWR, PSUM) and then run the virtual stations by spatially interpolating the computed variables. In this case, it is recommended to run the first set of simulations with the following set of keys:
And the second set of simulations (ie the ones relying on spatially interpolated forcings) with this set of keys: