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: : El Niño Phenomenon : :

The El Niño Phenomenon was given that name by the fishermen of Peru and Ecuador because it appeared as an abnormally warm current near Christmas and it was related with the birth of Jesus.

With the end of the "El Niño" phenomenon we refer to it as an event in the Climate Variability that's produced by the interaction in the conditions of the ocean and the atmosphere in the Tropical Pacific Ocean. When we speak of "El Niño", we reffer to a warming in the waters of the Tropical Pacific Ocean. This warming of the surface of the sea produces a change in the ocean circulation and in the atmosphere, creating climate variations in a planetary level.

One of the most important variables in the monitoring of the "El Niño" and "La Niña" Phenomena in the Sea Surface temperature in the Tropical Pacific Ocean. This is why the Tropical Pacific Ocean has been dividen into 4 regions, which are constantly monitored to diagnose and forecast the "El Niño" or "La Niña" evolution.

Location of the El Niño Regions

Picture N° 1,
Location of the El Niño Regions

The picture N° 1 shows a representation of the 4 Regions for El Niño (Taken from the ENSO Cycle: Recent Evolution, Current Status and Predictions, from NOAA).  The yellow box, represent the area that covers the zone Niño 4, the black box indicate the zone Niño 3.4, the red one is the region Niño 3 and the white one, near the South American West Coast, represent the regionNiño 1+2; Later we'll show the sea temperature forecast in these 4 regions of the ocean.

Current Development State for El Niño

Temperature Evolution

Picture N°2. Temperature evolution for the sea surface in the 4 El Niño regions.

According to the Climate Prediction Center in NOAA, the El Niño conditions strengthen during the month of December 2009, as the sea surface temperatures rose from the normal threshold (abnormality superior to the + 0.5°C) through the center and east of the Equatorial Pacific Ocean. The abnormalities in the sub-surface temperature of the ocean exceeded the 2°C through a big part of the Equatorial Pacific, with the biggest difference in the east basin part, at the end of December. Besides, the abnormality of the western wind abnormality in the low levels and from the east in the high levels over the Equatorial Pacific, these conditions are consistent with "El Niño", with a convection continuation over Indonesia and an increase of the convection in the center and western Equatorial Pacific. These ocean and atmospheric conditions reflect that "El Niño" is still strong.

In picture N°2, you can see the temperature behavior for the sea surfave in the 4 monitored zones for "El Niño", from February 2009 through January 2010. The dark yellow color shows the time in which the temperature abnormalities have been over the normal and the light blue the times that have been under the normal. Observe that currently (in the first days of January 2010) the for regions exhibit abnormalities higher than normal. ¹


El Niño Forecast

There's still disagreement between the models with relation to the maximum intensity point in El Niño. So far, is expected that the three months average in the surface temperature in the El Niño-3.4 region exceeds +1.5 °C in the winter of the northern hemisphere (November - December - January and December - January - February). No matter which one is the maximum intensity, is expected that "El Niño" continues to influence substancially in global weather and climate during the next few months. Most of the models suggest that the abnormalities in sea surface temperature for the region El Niño-3.4 will start to decrease in the early 2010, but the "El Niño" shall persist untill April - May - June of the present.

In the next graphics N°1 ¹, N°2 ², N°3 ³ y N°4 *, are presented the temperature forecast for the 4 monitored regions, produced by the Climate Prediction Center in NOAA. Observe that in the 4 "El Niño" regions, is anticipated that the "El Niño" conditions persist until the trimester April, may, June 2010. These forecast are updated according to the evolution of the conditions in the ocean and the atmosphere in the following months.

¹ Tomada de
² Tomada de
³ Tomada de
* Taken from

Graphic 1

Graphic N°1.
Sea surface temperature forecast for the region Niño 1+2

Graphic 2

Graphic 2.
Sea surface temperature forecast for the region Niño 3.

Graphic 3

Graphic N°3.
Sea surface temperature forecast for the region Niño 3.4.

Graphic 4

Gráfica N°4.
Sea surface temperature forecast for the region Niño 4.

Observed Effect of El Niño in Panama

During the month of June 2009, occured a transition in the conditions of the Equatorial Pacific Ocean from ENSO-neutral conditions to "El Niño" conditions. The chart #1 present the monthly behevior for the rain in 9 stations in our country, from June (El Niño starting date) to January 2010. From this group the Bocas del Toro station represents the conditions in the Caribbean slope and the other 8 stations represent the Pacific slope conditions.

The data are represented as percentage, the reds represent rain deficit and the backs excess.

  june july august september october november december january 2010
Bocas del Toro -68 3 5 -4 84 28 -47 7
David 5 -11 -29 -46 -19 48 -38 -4
Santiago -17 16 -15 -58 36 30 -7 -97
Tonosí 1 37 21 -6 29 116 -51 -100
Los Santos 79 -20 30 -56 13 -13 -64 -100
Divisa -7 -30 -55 -74 -15 35 -83 -100
Antón -26 34 -6 -59 -4 3 -100 -100
Hato Pintado 9 -4 41 -41 -7 18 -77 -100
Tocumen 11 64 32 -36 -15 24 -69 -100

Chart N° 1
Monthly behavior for the rain from june through december 2009, in percentage.

Stations Latitude Longitude Elevation (msnm)
Bocas Del Toro 09°20’ 82º15’ 2
David 08°24’ 82°25’ 27
Santiago 08°05’ 80°58’ 80
Tonosí 07°24’ 80°27’ 12
Los Santos 07°57’ 80°25’ 16
Divisa 08°06’ 80°41’ 12
Antón 08°23’ 80°16’ 33
Hato Pintado 09°00’ 79°31’ 45
Tocumen 09°03’ 79°22’ 14

Chart N° 2
Location of the meteorologic stations used in the analyses.

In chart N° 2 the coordinated for the 9 used stations to make the description of the behavior from June 2009 to January 2010 are presented.

In chart N°1 you can see the strong deficit registered the rain in the Bocas del Toro station, in the month of June and that it wasn't that strong in the Pacific slope.

During the months of July and August there were no general monthly deficits in the country, however when you analyze the daily data we find a bad distribution in the rain. The month of August was characterized by a large period of rainless days and few events of intense rains. The Los Santos station registered 15 rainless days, and in 2 days it registered 95% of the monthly rain. The Tonosi station registered in 1 day 52% of the monthly rain. In the Divisa station there were 21 days with rains smaller than 1 mm, this is equivalent to 21 days without rain, that bay distribution in the rain obbeys to the El Niño conditions, that were getting stronger in the Topical Pacific Ocean.

The months of Sepetember and December show strong general deficits in the 9 stations. Is important to highlight that some stations exceeded their historical deficits: Santiago and Divisa registered their dryest September in 39 and 45 years respectively. The David station presented the second dryest September in 42 recorded years. The Anton station registered the thrird dryest September in 40 recorded years.

In January 2010 there has been rain deficit in almost every analyzed station,excluding the Bocas del Toro station (7%).

Next you can see the graphics with the monthly rain behavior, expressed in percentage. The red bars represent the negative percentages, that is, months in which there was deficit rain and the blue ones the positive ones, that is, months in which the rain was superior to their historic value. Over each bar the deficit or excess percentage appears with the sign and color according to their meaning.

Is necesary to highlight the fact that the poor rain distribution is a direct effect of the El Niño conditions that prevailed during these months in the Tropical Pacific Ocean and that haven't only affected our country, but have been observed, in different ways, worldwide.

Rain excess or deficit in percentage Rain excess or deficit in percentage
Rain excess or deficit in percentage Rain excess or deficit in percentage
Rain excess or deficit in percentage Rain excess or deficit in percentage
Rain excess or deficit in percentage Rain excess or deficit in percentage
Rain excess or deficit in percentage

Prepared by:
Lic. Berta Olmedo
Climatology Supervisor
Hydrometeorology Management

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