La Nina Developing
After a near record El Nino this past fall and winter, a major reversal in sea surface water temperatures is taking place in the subtropical Pacific. These changes will mean different weather patterns for North America in at the end of 2016 and into 2017.
The very warm waters between Australia and South America over the past year are cooling. The above normal water temperatures (El Nino) are going to transition to colder than normal water temperatures by this fall (La Nina).
It is a normal sequence of events to transition from a very warm Pacific to a colder one. We have seen this before in previous years. The very strong El Ninos year of 1982/83 and 1997/98 were followed by the development of strong La Ninas.
This change in sea surface temperatures can result in wholesale changes in weather patterns from one year to the next. Although is some lag time between the changes in ocean temperatures and the related weather pattern changes, we can expect the impacts of the developing La Nina to show in the winter, spring and summer of 2017.
The graphic below is a sea surface temperature forecast for this fall (September, October, November).
Notice the west to east area of blue west of South America westward to northeast of Australia. The blue color indicates a forecast of below normal sea surface water temperatures by this fall. This would be a complete reversal of the El Nino (warmer than normal temperatures or red on the map).
By early winter La Nina is forecasted to become more intense. The graphic below shows the sea surface temperature forecast for December, January and February.
The area of cooling waters near the equator (as well as the warmer waters near the west coast and cold pool south of Alaska) will impact large scale weather patterns this fall and winter and spring of 2017.
It is too early to begin getting specific about temperatures and precipitation late this year and early 2017, however, odds are high that patterns will be different across the United States next year as compared to the past year.