1. El Niño–Southern Oscillation (ENSO): What is it?

2. Normal conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
Normal conditions in equatorial Pacific Ocean
Warm water in the western Pacific
Cold water in the eastern Pacific

3. Normal conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
Normal conditions in equatorial Pacific Ocean
Deep convective storms and heavy rain concentrated over warm water in western Pacific
Warm water provides “fuel” for storms

4. Normal conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
Normal conditions in equatorial Pacific Ocean
Walker Circulation is in place
Rising air over western Pacific, sinking motion over eastern Pacific
Winds: easterly (east to west) at surface, westerly (west to east) aloft

5. Normal conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
Normal conditions in equatorial Pacific Ocean
Upwelling brings cold water to the surface near the western coast of South America

6. El Niño conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
El Niño conditions in equatorial Pacific Ocean
Warm water spreads eastward across the Pacific

7. El Niño conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
El Niño conditions in equatorial Pacific Ocean
Convective storms shift eastward into central and eastern North Pacific, remaining fixed over warm water
Location of convective storms varies from event to event

8. El Niño conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
El Niño conditions in equatorial Pacific Ocean
Walker Circulation weakens
Surface easterlies weaken or become westerly
Upward motion develops over central/eastern Pacific

9. El Niño conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
El Niño conditions in equatorial Pacific Ocean
Upwelling decreases in eastern Pacific and warm water reaches coast of South America

10. La Niña conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
La Niña conditions in equatorial Pacific Ocean
Big difference in sea surface temperatures between western and eastern Pacific
Warm water in western Pacific, cold water in eastern Pacific

11. La Niña conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
La Niña conditions in equatorial Pacific Ocean
Convective storms shift westward, remaining fixed over warm water

12. La Niña conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
La Niña conditions in equatorial Pacific Ocean
Walker Circulation strengthens

13. La Niña conditions in equatorial Pacific Ocean
North America
Southeast Asia
South America
Australia
Source: NOAA/CPC
La Niña conditions in equatorial Pacific Ocean
Upwelling increases in eastern Pacific, and water is cold along coast of South America

14. Tracking the evolution of ENSO
Sea surface temperature departure from average over central equatorial Pacific – a commonly used ENSO measurement
El Niño
La Niña
Source: NOAA/CPC
Highly variable with lots of fluctuations; no regular cycle
El Niño or La Niña events typically last 9–12 months, sometimes even longer
On average, El Niños and La Niñas occur every 3–5 years
Impacts on ocean and atmosphere usually most significant in Northern Hemisphere

15. Ocean temperatures for past El Niño and La Niña events
Strong
El Niño event
Strong
La Niña event
Source: NOAA/CPC

16. Sea surface temperature anomalies
Current Conditions
Sea surface temperature anomalies
3–30 January 2016
Cooler than normal
Warmer than normal
Source: NOAA/CPC

17. Outgoing longwave radiation anomalies
Current Conditions
Fewer
clouds/rain than normal
Outgoing longwave radiation anomalies
3–28 January 2016
More
clouds/rain than normal
Source: NOAA/CPC

18. Links to animations
Recent evolution of Pacific sea surface temperatures:
Comparison between 1997 and 2015 sea surface temperatures:

19. Impacts of El Niño on wintertime weather over the U.S.

20. El Niño’s typical impact on wintertime
weather over the U.S.
Warmer than normal across northern U.S.
Wetter than normal across the southern U.S.
Drier than normal over northeastern U.S.
Source: NOAA/Climate.gov

21. Temperature relative to normal
How has El Niño affected the U.S. in past winters?
1982–1983
1997–1998
Temperature relative to normal
Cooler
Warmer
Precipitation relative to normal
Source: NOAA/ESRL
Drier
Wetter

22. Temperature relative to normal
What about this winter?
It was super warm in December 2015 over the U.S….and across the globe
Global temperature time series for
all Decembers on record
Temperature relative to normal
Cooler
Warmer
Source: NOAA/ESRL
Source: NOAA/NCDC
1880
2015
Warmest December on record for Albany, for New York State, for the U.S., and for the entire globe!

23. What about this winter?
…and it has been raining/snowing a lot in some areas
Precip anomaly for
Nov 2015–Jan 2016
Precipitation relative to normal
Source: NOAA/NWS
Drier
Wetter

24. Drought conditions in early October 2015
Source: National Drought Monitor

25. Current drought conditions
Drought has improved in many areas in the West!
Source: National Drought Monitor