A Rare Weather Pattern Is Upon Us

A 'triple dip' of La Nina, referring to 3 straight years of it, is here
By John Johnson,  Newser Staff
Posted Sep 12, 2022 2:34 PM CDT
A Rare Weather Pattern Is Upon Us
Homes are surrounded by floodwaters in Sohbat Pur city of Jaffarabad, a district of Pakistan's southwestern Baluchistan province, on Aug. 29, 2022. The UN weather agency is predicting the phenomenon known as La Nina, a driver of world climate, is poised to last through the end of this year.   (AP Photo/Zahid Hussain, File)

The weather pattern known as La Nina has materialized in the equatorial Pacific. If that factoid sounds familiar, it's because this is the third consecutive year for the phenomenon—and that marks the first time in a century such a "triple dip" has occurred, according to the World Meteorological Organization. La Nina is a major driver of world climate, with tangible effects in the US. Here's a look:

  • Definition: La Nina "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 atmospheric circulation, namely winds, pressure and rainfall," per the WMO. As USA Today notes, it's the opposite of El Nino, which arises when Pacific water is cooler than average.

  • US effects: The Southwest, "with rain clouds pushed out to sea, becomes drier than usual" under La Nina, per NPR. Northwestern US states and Canada "see cooler-than-average temperatures, rain and flooding." The Southeast and mid-Atlantic regions generally see warmer-than-average temperatures. The AP reports that La Nina generally leads to more hurricanes in the Atlantic, "less rain and more wildfires in the western United States, and agricultural losses in the central" US. Historically, La Nina tends to cause more economic damage to the US than El Nino.
  • World effects: La Nina is blamed for flooding in Asia as well as droughts in North and South America, and in eastern Africa, per ABC News. Australia and Indonesia tend to see heavier rain, notes NPR.
  • Context: "It is exceptional to have three consecutive years with a la Niña event," says WMO Secretary-General Petteri Taalas. "Its cooling influence is temporarily slowing the rise in global temperatures—but it will not halt or reverse the long-term warming trend." The agency predicts La Nina will be present through the end of the year.
(More La Nina stories.)

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