LO CUAL
The relative pronoun lo cual is used to refer to a complete idea in the antecedent, in example, a whole sentence. In order to be used, there must be an antecedent.Los meteorólogos han dicho que se acerca un huracán a la ciudad, lo cual ha puesto a la ciudad en alerta naranja.
Forecasters have said that a hurricane is approaching the city, which has put the city on red alert.