The bar at the bottom shows what temperature, in degrees Celsius, each color indicates in this image from Jan. 7. They often gave useful warning of those events three to six months in advance. Normally, easterly wind patterns shift and even reverse. Warm sea-surface water normally pooled in the western Pacific spreads eastward.
More moisture rises into the air as thunderstorm activity increases.
This feeds energy into the atmosphere that winds carry long distances. Dr. Busalacchi and other scientists at the meeting explained that this is a short-term climate shift. It is not weather. These include drought in Australia and floods in parts of South America. But the Pacific warming had much less effect on the state's rains earlier that winter.