ok so the entity parsed to the card entity_forecast_icon_1 should be that text entity. The condition needs to be one of the preset conditions in the card listed here: (from line 523 in the js file
'sunny': sunny_icon,
'clear': clear_icon,
'mostly-sunny': mostly_sunny_icon,
'partly-cloudy': partly_cloudy_icon,
'mostly_sunny': mostly_sunny_icon,
'partly_cloudy': partly_cloudy_icon,
'partlycloudy': partly_cloudy_icon,
'cloudy': cloudy_icon,
'hazy': hazy_icon,
'hazey': hazy_icon,
'haze': hazy_icon,
'frost': frost_icon,
'light-rain': light_rain_icon,
'light_rain': light_rain_icon,
'wind': windy_icon,
'windy': windy_icon,
'fog': fog_icon,
'foggy': fog_icon,
'showers': showers_icon,
'shower': showers_icon,
'rain': rain_icon,
'rainy': rain_icon,
'dust': dust_icon,
'dusty': dust_icon,
'snow': snow_icon,
'snowy': snow_icon,
'snowy-rainy': snow_rain_icon,
'snowy_rainy': snow_rain_icon,
'snowyrainy': snow_rain_icon,
'storm': storm_icon,
'stormy': storm_icon,
'light-showers': light_showers_icon,
'light-shower': light_showers_icon,
'heavy-showers': heavy_showers_icon,
'heavy-shower': heavy_showers_icon,
'light_showers': light_showers_icon,
'light_shower': light_showers_icon,
'heavy_showers': heavy_showers_icon,
'heavy_shower': heavy_showers_icon,
'pouring': heavy_showers_icon,
'tropical-cyclone': cyclone_icon,
'tropical_cyclone': cyclone_icon,
'tropicalcyclone': cyclone_icon,
'clear-day': clear_day_icon,
'clear-night': clear_night_icon,
'clear_day': clear_day_icon,
'clear_night': clear_night_icon,
'sleet': sleet_icon,
'partly-cloudy-day': partly_cloudy_day_icon,
'partly-cloudy-night': partly_cloudy_night_icon,
'partly_cloudy_day': partly_cloudy_day_icon,
'partly_cloudy_night': partly_cloudy_night_icon,
'hail': hail_icon,
'lightning': lightning_icon,
'lightning-rainy': lightning_icon,
'lightning_rainy': lightning_icon,
'thunderstorm': lightning_icon,
'windy-variant': windy_variant_icon,
'windy_variant': windy_variant_icon,
'exceptional': '!!',
You also need to have installed the icons