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NOAA satellite image of developing El Niño.April 11, 2002 — NOAA scientists said today the United States could start feeling the impacts of the developing El Niño as early as mid-summer. The scientists cautioned that the strength of the expected El Niño is still unknown. Depending on its strength, the El Niño impacts could range between fewer Atlantic hurricanes and a drier-than-normal summer monsoon season in the southwest, to more Nor'easters next winter. NOAA is an agency of the U.S. Commerce Department. (Click NOAA image to see latest sea surface temperatures.)

"This El Niño is still forming, and it's unclear now at what level of intensity it will be once it's fully developed," said Vice Adm. Conrad C. Lautenbacher, USN (ret.), NOAA's administrator. "If sea-surface temperatures continue their warming trend in the equatorial Pacific, we'll likely know the intensity by late May or June." He added April and May typically have been the best months for clues on intensity as El Niño episodes take shape.

Scientists observed a continuation of warmer-than-normal sea-surface and sub-surface temperatures across much of the equatorial Pacific. Last month, ocean surface temperatures were as high as 2 to 3 degrees C (4 to 6 F) above average near the coasts of Ecuador and northern Peru. (Average ocean surface temperatures are about 27 degrees C [81 F] in this region during March.)

Also, increased rainfall and cloudiness were observed over the extreme eastern tropical Pacific, including the Galapagos Islands, and over the west-central equatorial Pacific. As El Niño continues to develop, scientists said the possible impacts on the United States include:

  • Fewer tropical systems during the Atlantic hurricane season;
  • Higher number of Nor'easters along the East Coast during the 2002-2003 winter;
  • A drier-than-normal summer monsoon season in the southwest;
  • A drier-than-normal fall and winter for the Pacific Northwest;
  • A warmer-than-normal late fall and winter in the northern Great Plains and upper Midwest, and
  • A wetter-than-normal winter for the Gulf Coast states.

If the intensity of the El Niño is strong, central and Southern California could experience wetter-than-normal conditions.

"One of our major research findings is no two El Niño episodes are alike," said Brig. Gen. Jack Kelly USAF (ret.), director of NOAA's National Weather Service. "Americans have vivid memories of the effects of the strong 1997-98 El Niño, making many people wary of this one. But we will need to follow developments closely in the coming months to determine just how strong or weak this El Niño may get."

El Niño conditions occur when water temperatures have warmed sufficiently to alter the normal patterns of cloudiness and rainfall in the tropical Pacific basin. A typical El Niño features persistent, increased precipitation along the equator near the international dateline, and warmer-than-normal sea-surface temperatures (at least 0.5 C [1 F] above normal) extending eastward to the South American coast.

El Niño episodes occur about every four-to-five years and can last up to 12-to-18 months. NOAA will continue monitoring El Niño developments and provide monthly updates. The El Niño/Southern Oscillation Diagnostic Discussion is a team effort consisting of the Climate Prediction Center (lead), Climate Diagnostics Center, Geophysics Fluid Dynamics Laboratory, National Climatic Data Center, Atlantic Oceanographic and Meteorological Laboratory, and the International Research Institute for Climate Prediction.

NOAA's National Weather Service is the primary source of weather data, forecasts and warnings for the United States and its territories. The National Weather Service operates the most advanced weather and flood warning and forecast system in the world, helping to protect lives and property and enhance the national economy.

Relevant Web Sites
NOAA's Climate Prediction Center

El Niño/Southern Oscillation (ENSO) Diagnostic Discussion

Most Recent 2 Months Sea Surface Temperature Anomaly Animation

El Niño and La Niña-related Winter Features over North America

NOAA's El Niño Theme Page

NOAA's El Niño Home Page



ENSO Fact Sheet

ENSO Frequently Asked Questions

ENSO Tutorial

ENSO Recent Events

Sea Surface Temperature Outlook

ENSO Impacts by Region

Media Contact:
Carmeyia Gillis, NOAA's Climate Prediction Center, (301) 763-8000 ext. 7163