What is the Pineapple Express and where is it going?

After an unusually dry January, a weather system called an atmospheric river - or Pineapple Express - is now headed towards northern California.

Pineapple Express events have the potential to bring huge quantities of rain, as well as snow to higher ground.

The BBC Weather's Elizabeth Rizzini looks at the meteorological phenomenon and what to expect from it in the week ahead.