Contact: Stephanie Kenitzer FOR IMMEDIATE RELEASE
11/5/97
A combination of strong El Nino conditions and the normal seasonal warming of the tropical Pacific Ocean will keep the ocean sufficiently warm to impact global weather patterns through late winter and early spring, according to a Special Climate Summary released today by the Commerce Department's National Oceanic and Atmospheric Administration.
"This event is still going strong and will likely continue on this track into early 1998," said Ants Leetmaa, director of NOAA's Climate Prediction Center, in Camp Spring, Md. "Combined with the normal, annual warming of this part of the Pacific Ocean, the sea surface temperatures will remain warm enough to impact global weather patterns into the spring."
El Nino is an abnormal warming of the ocean temperatures across the eastern tropical Pacific that brings important consequences for weather around the globe. The warm tropical ocean waters first appeared in March 1997 and quickly strengthened to become one of the strongest El Nino events on record.
Observations from data buoys and satellites indicate that waters in the eastern Pacific have averaged at least 82 degrees Fahrenheit since April 1997, approximately 8 degrees Fahrenheit above normal. The warm water covered more than 9.5 million square miles during September.
The warmer Pacific Ocean waters are accompanied by weak trade winds and a shift of heavy tropical rainfall into the central and eastern equatorial Pacific. The climate phenomenon typically brings wetter, cooler weather for the southern half of the United States from November through March, while the northern part of the country from Washington east to the western Great Lakes experiences warmer than normal temperatures.
"California, Texas, Florida and other states throughout the south are likely to see significant precipitation in the next several months," added Leetmaa. "Based on historical data during past El Nino events, some areas may see as much as 150 to 200 percent of normal. While we tend to view the increased precipitation as a threat, in some instances there are benefits such as decreasing the chance for wintertime drought in the Southwest and southern Plains and reducing the wildfire danger in Florida."
El Nino has already impacted weather patterns across the globe this summer and early fall, including significantly less rainfall in Indonesia and a dramatic decrease in tropical storm and hurricane activity in the Atlantic. Drier than normal conditions have affected Mexico, Central America and other portions of South America. A stronger than normal southern hemisphere jetstream has produced wetter than normal conditions in Chile and in large portions of central and southern South America. Some locations in Chile received their normal annual rainfall total in a single day.
El Nino episodes usually occur approximately every two to seven years. Recent El Nino events occurred in 1976-1977, 1982-1983, 1986-1987, 1991-1993 and 1994-1995. The first half of the 1990's is unusual in that four out of five years featured warm episode conditions in the tropical Pacific. A cold episode occurred in 1995-96 and its effects lingered until late1996.
NOAA works closely with the academic and science community on climate-related research projects to increase the understanding and future predictions of El Nino. NOAA's Climate Prediction Center monitors, analyzes and predicts climate events ranging from weeks to seasons for the nation. NOAA also operates the network of data buoys and satellites that provide vital information about the ocean waters, and initiates research projects to improve future climate forecasts.
The Special Climate Summary and updates on tropical El Nino developments are available on the Internet through NOAA's Climate Prediction Center at http://nic.fb4.noaa.gov under "El Nino" and then under "Special El Nino Summary" or at http://nic.fb4.noaa.gov:80/products/special_summaries/97_3/index.html