What is El Niño?

• A description of how El Niño forms and the effect of El Niño on Southwest weather.

Streamflow and Flooding:

• The Southwest experiences enhanced streamflow and seasonal snow water content during the mature winter phase of El Niño. The various conditions that can lead to flooding are affected by El Niño in different ways from region to region and from event to event.

Lake Level Rise:

• Any long-term increase in precipitation and runoff in the arid southwest (like during an El Niño) potentially can lead to rising water levels of terminal lakes.

Landslides and Debris Flows:

• Some of the most destructive landslides and debris flows in the Southwest over the past few decades have occurred during El Niño events.