Another La Niña Winter – Why Do Gardeners Care?
Forecasts indicate a 75 percent chance that La Niña—the cool phase of the ENSO climate pattern—will persist across the tropical Pacific for the third winter in a row. The map below shows the broad swath of cooler-than-average water (blue) across the Pacific at the equator, one of the hallmarks of La Niña. That means another dry winter for New Mexico.
El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short. The pattern shifts back and forth irregularly every two to seven years, bringing predictable shifts in ocean surface temperature and disrupting the wind and rainfall patterns across the tropics. These changes have a cascade of global side effects.
La Niña strengthens the normal atmospheric circulation across the tropical Pacific Ocean. One side effect is a strong high pressure area in the Northeast Pacific. Like a boulder in a river, this high pressure changes the flow of storms as they approach the western U.S., favoring wet winters in the Northwest and dry winters across the South.