In a possible sign that La Niña is coming, sea surface temperatures along the equator in the east-central Pacific Ocean are trending cooler than the long-term average, as seen here in blue colors. (Credit: Climate.gov/NNVL)
Something is stirring in the tropical Pacific Ocean, and by fall it may begin to disrupt weather patterns worldwide.
For weeks now, a blob of cold water has been rising from the depths along the equator, and lately it has been helping to cool off a broad swath of the surface stretching from South America to the central Pacific.
This cross-section of a portion of the tropical Pacific Ocean shows how temperatures have departed from average between early April and early May 2020. The blue feature is an area of colder than normal water that expands and rises toward the surface over time. (Credit: Climate.gov figure from CPC data)