**** Info via Environment Canada
La Niña 2020 update.
According to the World Meteorological Organization (WMO), La Niña has developed and is now expected to last into next year, affecting temperatures, precipitation and storm patterns in many parts of the world.
Probability for November 2020 to January 2021 of a La Niña event. Credit: WMO.
This year’s La Niña is expected to be a “moderate to strong” event. The last time there was a strong event was in 2010-2011, followed by a moderate event in 2011-2012. However, as WMO Secretary-General Professor Petteri Taalas noted, recent La Niña events have had little cooling effect on a global scale.
“La Niña typically has a cooling effect on global temperatures, but this is more than offset by the heat trapped in our atmosphere by greenhouse gases. Therefore, 2020 remains on track to be one of the warmest years on record and 2016-2020 is expected to be the warmest five-year period on record,” said Professor Taalas. “La Niña years now are warmer even than years with strong El Niño events of the past.”
La Niña refers to the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical wind circulation, pressure and rainfall. It usually has the opposite impacts on weather and climate as El Niño, which is the warm phase of the so-called El Niño Southern Oscillation (ENSO).
Typical circulation patterns during El Niño/La Niña. Credit WMO.
Credit: National Oceanic and Atmospheric Administration Climate.
For more: ENSO and global seasonal climate updates.