In May and June each year, speculation about the coming of the monsoon fills newspapers and conversations across India. Everyone is concerned about if, when, and how much rain will arrive. But none have more at stake than India’s over 100 million farming households.

The Pacific-North American teleconnection pattern influences regional weather by affecting the strength and location of the East Asian jet stream, and subsequently, the weather it delivers to North America.

Over the span of days or weeks, the strength of surface air pressure over the North Atlantic seesaws between Iceland and the Azores Islands. The shifting pressure reflects changes in atmospheric circulation that have a big impact on mid-latitude weather in the U.S. and Europe. 

The Arctic Oscillation (AO) refers to an atmospheric circulation pattern over the mid-to-high latitudes of the Northern Hemisphere. The most obvious reflection of the phase of this oscillation is the north-to-south location of the storm-steering, mid-latitude jet stream.

“El Niño is Strong!” “No, it’s Moderate!” “But the [insert your favorite ENSO indicator here] is the largest it’s been since the El Niño of 1997-98!”

reason for the spring barrier

Why is it so difficult to make a good ENSO prediction during the Northern Hemisphere spring? 

You're not the only one wondering if we will see El Niño grow or continue into this coming winter 2015.  How useful are March winds and subsurface temperatures across the tropical Pacific Ocean in predicting winter El Niño or La Niña states?  

ENSO model forecasts thumbnail

The model predictions during 2014 were not that shabby.  A major, strong El Niño was not well justified by the predictions. 

A first look at how we evaluate seasonal forecasts. How well do our eyes do?

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