El Nino Watch
Steady winds that blow from east to west along the equator. They push warm surface water towards Asia. When they weaken, El Nino can grow.
El Nino basics
Near the equator, surface winds normally blow from the east (they are called "easterlies"). They drag the warm top layer of the ocean west, so the water piles up near Indonesia and the sea level there is higher.
When the trade winds weaken, the warm water sloshes back east. That is the start of El Nino. A burst of wind from the west (a Westerly wind burst (WWB)) can give it an extra push.