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Condition ripe for new El Niño weather pattern, NWS says

By the OGJ Online Staff

HOUSTON, Jan. 14, 2002 — The National Weather Service said a new El Niño phenomenon could be in place by spring with the effects being felt by fall in the US.

A warming trend is being observed over the tropical Pacific, which could lead to an El Niño, according to the National Oceanic & Atmospheric Administration (NOAA). The US is not expected to experience its potential impact until late summer, through the fall and into next winter.

The most recent El Niño took place in 1997-1998 and was extremely severe, including its effect on energy markets. In the US it was marked by flooding rains in California and along the Gulf Coast and wildfires in Florida. NOAA’s said its long-range prediction led California to conduct major mitigation efforts cutting losses by about $1 billion.

NOAA cautioned the public that it is too early to predict the magnitude of the potential 2002 El Niño, or how long it would last. “The magnitude of an El Niño determines the severity of its impacts,” said Vernon Kousky, NOAA climate specialist. “At this point, it is too early to predict if this El Niño might develop along the same lines as the 1997-98 episode, or be weaker,” said Kousky.

If El Niño develops as is presently indicated, NOAA said the Pacific Northwest will experience drier than normal conditions in the fall. In the winter, Louisiana eastward to Florida, and possibly southern California, could experience wetter than normal conditions, and the northern Great Plains will experience warmer than normal conditions. Indonesia is likely to realize some relief from recent torrential rains.

“Considering the observed oceanic and atmospheric circulation patterns and their recent evolution, it seems most likely that warm-episode conditions will develop in the tropical Pacific over the next 3-6 months,” said Kousky.

Historically, El Niño episodes have occurred every 2 to 7 years and can last up to 12 months. The prediction is based on increasing cloudiness and rainfall over the equatorial central Pacific for the first time since the 1997-98 El Niño episode. Indications for a warm episode, or El Niño, in the tropical Pacific was first noted in August 2001.

Near the end of each calendar year ocean surface temperatures warm along the coasts of Ecuador and northern Peru. Local residents referred to this seasonal warming as “El Niño”, meaning The Child, due to its appearance around the Christmas season.

Every 2 to 7 years a much stronger warming appears, which is often accompanied by beneficial rainfall in the arid coastal regions of these two countries. Over time the term “El Niño” began to be used in reference to these major warm episodes.

The abnormally warm waters in the equatorial central and eastern Pacific give rise to cloudiness and rainfall in that region, especially during the boreal winter and spring seasons. At the same time, rainfall is reduced over Indonesia, Malaysia, and northern Australia.

NOAA said it will continue to carefully monitor its evolution. The next scheduled update will be in early February 2002.


For more information, please see the NOAA web site on El Nino and La Nina at http://www.cpc.ncep.noaa.gov.