El Nino describes a climate pattern that occurs when the surface waters of the eastern equatorial Pacific Ocean show unusual warming. It can affect weather around the world.
The warming of the waters tends to peak in December.
El Nino is Spanish for "the boy" (referencing the Christ Child due to occurrence in December).
It tends to occur at irregular intervals every 2-7 years.
Climate effects:
(1) weakening of the westward trade winds in the Pacific
(2) reduced upswelling in the eastern Pacific
(3) the Pacific jet stream moves south.
(4) high air pressure in the western Pacific and low air pressure in the eastern Pacific
Effects on the weather in the United States:
(1) increased moisture to the Southern United States, Central America and South America, with increased risk of flooding
(2) warmer weather in Alaska, Canada and the Northwest
(3) drier weather in the Midwest, with risk of drought
Other effects
(1) change in fish populations
(2) increased risk of wildfires
(3) deepening of the thermocline (the demarcation from warm surface to cold deep waters).
