Evans Maru Magdalene WanjikuNoah AdamPurity Mueni Adrajow Admasu

What Is El Niño?El Niño is a term that refers to anomalously

warmer than average Sea Surface Temperatures

(SSTs) in the eastern and central equatorial Pacific

Ocean. It is normally characterized by warming of

the subsurface layers and large scale weakening of

the trade winds in the region.

These changes have important consequences over

weather/climate around the globe, including East

Africa.

La Nina

Scientists refer to the event when

exceptionally cool water lies off the coast

of South America as La Nina Strong La

Nina events have been responsible for the

opposite effects on climate as El Nino.

Strongest El Niño's

4

Very strong El Nino events occurred in 1965-

1966, 1982-1983, and 1997-1998. They caused

significant flooding and damage from California to

Mexico to Chile. Effects of El Nino are felt as far

away from the Pacific Ocean as Eastern Africa

including Kenya.

NB: An El Nino year correspond to the first three

months of the ENSO year namely October,

November, and December. For example, the

ENSO year 1970 starts October 1970 and ends

September 1971.

5

The El Nino of 1997

Strongest La Ninas

6

Strong La Nina events occurred in 1955-56,

1964-65, 1973-74, 1988-89 and 1998-2000.

They were associated with drought over most

parts of Eastern Africa including Kenya.

NB: An La Nina year correspond to the first

three months of the ENSO year namely

October, November, and December. For

example, the La Nina year of 1988 started in

October 1988 and ended in September 1989.

The La Nina of 1988

7

Classification El Ninos & La Ninas

8

El Ninos & La Ninas are classified as either

Weak, Moderate or Strong depending on the

extent of warming/cooling in the Nino areas.

Sub-Surface Temperature Departures in the Equatorial Pacific

Since mid September, positive subsurface

temperature anomalies have stretched across

most of the equatorial Pacific.

Recently, positive subsurface anomalies in the

central Pacific are expanding eastward. Negative

anomalies in the eastern Pacific are

strengthening at depth.

Recent Evolution of Equatorial Pacific SST Departures (oC)

Average SST Departures (oC) in the

Tropical Pacific During the Last Four Weeks

Weekly SST Departures during the Last Four WeeksDuring the last four weeks, positive SST

anomalies persisted along the equatorial

Pacific and strengthened in the eastern

Pacific.

From 15 October to 05 November 2014,

equatorial SSTs were above average across

most of the Pacific.

ONI (ºC): Evolution since 1950

The most recent ONI value (August – October 2014)

is 0.2oC.

CPC/IRI Probabilistic ENSO Outlook Updated: 6 November 2014

The chance of El Niño is 58% during the Northern Hemisphere winter and decreases into Spring/summer 2015.

IRI/CPC Pacific Niño 3.4 SST Model Outlook Most models favor El Niño (greater than or equal to +0.5ºC) to develop during October-December 2014 and persist through Northern Hemisphere spring 2015.

Figure provided by the International Research Institute (IRI) for Climate and Society (updated 16 October 2014).

Summary

ENSO Alert System Status: El Niño Watch

ENSO-neutral conditions continue.*

Positive equatorial sea surface temperature

(SST) anomalies continue across most of the

Pacific Ocean.

There is a 58% chance of El Niño during the

Northern Hemisphere winter, which is favored to

last into the Northern Hemisphere spring 2015.*

Merci et a

u

revoir