The forecast data is an array, so to get specific data points from that you can use a Template sensor or similar. Let us say you want to get the condition value from the second day in the forecast, then you would use:
{{ state_attr('weather.weatherflow_day_based_forecast', 'forecast')[1].condition }}
Note the number 1: As this is a zero based array, 1 is the second item in the list. So just change the day number and the field name, to get what you need. Hope this pushes you in the right direction.