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The El Nino of 1997-1998

By: Christopher C. Burt, 9:10 PM GMT on March 10, 2014

The El Niño of 1997-1998

As Jeff Masters blogged on March 6th, NOAA has issued an El Niño watch for later this year with a 50% chance of an El Niño forming. The last major El Niño event was that of 1997-1998. Here’s a very brief summary of some highlights.

A graph of the Oceanic Niño Index between 1950-2014. The El Niño of 1997-1998 was the strongest in modern records. Table from Jan Null of Golden Gate Weather Services.Sorry about the poor resolution of this table (WU can only give me 720 horizontal dpi for blog graphics (to fit the screen), so visit Jan's web site for a full resolution of this chart (and more details).

Not all El Niño’s have the same affects globally but one place that is always adversely affected is Peru (where the term ‘El Niño’ was first used). The warming of the Eastern Pacific during an El Niño event always contributes to higher than normal rainfall in Peru, sometimes, as was the case in 1997-1998, catastrophically so. One location, Tumbes, in northwestern Peru, received 2,100 mm (82.7”) of precipitation between December 1997 and May 1998, including 730 mm (28.7”) in January alone. The normal rainfall for Tumbes between December-May is just 200 mm (8”). Flooding and mudslides killed over 200 in Peru and over 250 in Ecuador. The Peruvian government said that damage to the nation’s infrastructure cost US$2 billion. In September of 1997 Hurricane Linda formed off the coast of Mexico and developed into the strongest Eastern Pacific tropical cyclone on record with sustained winds reaching 185 mph and a central barometric pressure as low as 900 mb (26.58”) on September 12th. A month later, Hurricane Pauline hit Mexico killing 250-400 people and dropping 686 mm (27.01”) of rainfall in 24 hours on the town of San Luis Actatlan, the 2nd heaviest rainfall recorded in Mexico as a result of a Pacific Hurricane. In the Western Pacific, three of the top 10 most intense typhoons on record formed (two of them simultaneously): Super Typhoon Joan (872 mb/25.75” on Oct. 19), ST Ivan (872 mb on Oct. 18), and ST Keith (878 mb/25.92”) on Nov. 2nd.

Pacific Ocean surface temperature anomalies at the time that the El Niño of 1997-1998 was at its peak strength on December 1st, 1997. NASA/JPL.

In the U.S., the most significant manifestation of the El Niño were the record rainfalls in California during the water season of 1997-1998. Santa Barbara received 21.74” of precipitation in February alone contributing to its wettest water season on record (July 1-June 30) with a 46.99” total. Other California cities that reported their wettest season on record included Bakersfield (14.66”), Fort Bragg (79.13”), Monterey (47.12”), and Santa Maria (32.56”).

Meanwhile, on the other side of the Pacific, Indonesia endured one of its worst droughts on record and 1998 was one of the warmest years for much of East and Southeast Asia (Malaysia recorded its hottest temperature on record with a 40.1°C/104.2°F reading at Chuping on April 9th) and in Mongolia temperatures peaked at 42.2°C (108°F) during the summer of 1998.

In Africa, Kenya had one of its wettest years on record while Mozambique one of its driest. Floods in central Europe killed 55 in Poland and 60 in the Czech Republic.

A simplified map of how the El Niño of 1997-1998 affected weather events around the world. From Shrimp News.

Overall, the year 1998 became the warmest globally ever observed up to that time.

The 1997-1998 El Niño event, of course, was exceptionally strong and it does not (yet) appear that if an El Niño develops later this year it will be of such intensity. Also, weak or moderate El Niño’s have varying effects on global climate so, for instance, an El Niño next winter does not necessarily mean a wet water season for California.

REFERENCES: Some good popular material about the El Niño of 1997-1998 can be found in the March-April 1999 issue of Weatherwise magazine, the March 1999 issue of National Geographic, and the August 1998 issue of Popular Science.

Christopher C. Burt
Weather Historian

Extreme Weather El Nino

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.