What is ENSO? We meteorologists love our acronyms. ENSO is short for the El Niño-Southern Oscillation. El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical pacific.
La Niña is materializing for the second year in a row:
Allow me to explain…
Normally trade winds which blow east to west push warm surface waters towards Asia.
However, in certain years, trade winds are stronger than usual, causing cooler water to surface in the Eastern Pacific.
This is a typical wintertime pattern during La Niña.
La Niña winters support conditions that are:
- Drier in the southwest
- Drier and warmer conditions across the south and southeast
- Cooler and wetter in the northwest
- Wetter and warmer in the northeast
La Niña is also associated with a more variable jet stream which is supportive of more active weather.
Expect increased snowfall over the Northwest and northern Rockies and more tornado days in the Midwest.
An above average hurricane season is also a downstream effect of La Niña and we have already seen that unfold this year.