After El Niño dramatically impacted last summer’s weather, this year scientists are predicting a quick switch to La Niña.
“The atmospheric part of El Niño—the warm phase of the El Niño-Southern Oscillation (“ENSO”) climate pattern—has more or less shut-off,” the National Oceanic and Atmospheric Administration said. “The ocean part is weakening. Conditions are likely to shift to ENSO-neutral in the next month. La Niña, the cool phase of ENSO, could emerge as soon as June-August.”
NOAA put the odds of La Niña developing between June-August at 49% or July–September at 69% chance.
But what, exactly would it mean if a La Niña developed?
What is El Niño?
El Niño (meaning “little boy” in Spanish) is a “warming of the ocean surface, or above-average sea surface temperatures, in the central and eastern tropical Pacific Ocean,” according to the National Oceanic and Atmospheric Administration (NOAA). “Trade winds weaken. Warm water is pushed back east, toward the west coast of the Americas.
That, in turn, impacts the weather, often in significant ways. During an active El Niño, there will generally be more flooding in the U.S. Gulf Coast and southeast parts of the country, NOAA explained.
What is La Niña?
La Nina, which means “little girl” in Spanish, has the opposite effect of El Niño, according to NOAA.
“During La Niña events, trade winds are even stronger than usual, pushing more warm water toward Asia,” NOAA stated. “Off the west coast of the Americas, upwelling increases, bringing cold, nutrient-rich water to the surface…These cold waters in the Pacific push the jet stream northward.”
Because cold waters in the Pacific push the jet stream northward during La Niña, more droughts can occur in the southern U.S. with heavy rains and flooding occurring at the same time in the Pacific Northwest and Canada.
“Winter temperatures are warmer than normal in the south and cooler than normal in the north” part of the U.S. when La Nina is active, NOAA stated.
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How Can La Niña Impact Hurricane Season?
A La Niña can mean a much harsher hurricane season in the Atlantic.
“El Niño favors stronger hurricane activity in the central and eastern Pacific basins, and suppresses it in the Atlantic basin,” NOAA stated. “Conversely, La Niña suppresses hurricane activity in the central and eastern Pacific basins and enhances it in the Atlantic basin.
