La Nina Conditions Return

by | Dec 19, 2016

The strongest predictor of North American winter weather is what scientists call “El Nino Southern Oscillation”, or just, ENSO.

ENSO refers to the oscillation of high and low pressure between Tahiti and Darwin, Australia, which coincides with the formation of warming or cooling surface water in the eastern Pacific Ocean off the coast of central and south America.

On 12 December 2016, the National Weather Service officially announced that La Nina (cool surface water) conditions have formed in the Pacific. Graphics showing these conditions are presented below.

La Nina Conditions

The first figure shows very strong La Nina conditions in December 1988, the second strong shows El Nino conditions in 1997.

la nina conditions return

During La Nina, the southern United States is usually drier and warmer than normal. Unfortunately, this includes southern California, which is struggling to climb out of a long term drought.

The northwestern United States is wetter than normal but the upper mid-west usually gets a double dose of low temperatures and above average precipitation.

The weather for the northeast is generally average for both temperature and precipitation.

Weather Projections Early 2017

The winter weather projections from the National Weather Service for January, February, and March are shown in Figures 2a (temperature) and 2b (precipitation) below.

la nino conditions return - temperature

la nina conditions return-precp

Both figures support the general weather patterns predicted by La Nina conditions.

After last year’s “Monster El Nino”, everyone should expect a change in winter weather in 2017.

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