The forecast numbers you see on TV are provided by the local TV station Meteorologist him/herself, given their knowledge of local or regional forecast patterns, based on their professional Meteorological experience for the local areas.
Conversely, the digital forecast numbers you see on the website or mobile app are generated by automated data, without a human Meteorologist's oversight. These numbers come from a third-party partner.
Generally speaking, a forecast is an estimate, and different triggers - such as varying computer forecast models, human interpretation of those models, and strictly automated computer data - should be taken into consideration when comparing forecasts between various sources.
Because the Meteorologist has the knowledge of the area, we recommend leaning towards their recommended forecast if there are any varying reports.