NOAA U.S. WINTER OUTLOOK
Oct. 6, 2004 ó NOAA scientists today announced that a number of climate conditions will influence the winter weather across the United States from December through February. The NOAA 2004-2005 Winter Outlook calls for above-average temperatures in Alaska, much of the West and the northern and central Great Plains. Below average temperatures are expected across the Gulf Coast states, the Southeast and the mid-Atlantic region of the U.S. There are equal chances of warmer, cooler or near-normal temperatures this winter in the Northeast, Midwest and parts of Southwest. (Click NOAA image for larger view of forecast winter temperatures for the USA. Click here for high resolution version, which is a large file. Please credit “NOAA.)
The precipitation outlook calls for wetter-than-average conditions in parts of California, the extreme Southwest and across the Southern U.S.—from Texas to Florida. Drier-than-average conditions are expected in the Midwest, northern Plains and Pacific Northwest.
The winter outlook indicates some improvement in drought conditions in the West, but long-term drought is expected to persist through the winter in many areas.
NOAA will update its winter outlook on Oct. 21.
The winter outlook reflects a blend of impacts associated with weak-to-moderate El Niño events in the central equatorial Pacific Ocean and is based on the likelihood that these conditions will persist through early 2005. El Niño influences the winter weather patterns by affecting the jet stream and the track storms take across the eastern Pacific and North America. NOAA scientists do not expect this El Niño to reach the strength of the1997-1998 El Niño event. (Click NOAA image for larger view of forecast winter precipitation for the USA. Click here for high resolution version, which is a large file. Please credit “NOAA.)
"Our winter forecast factors in the effects of a weak El Niño that may strengthen into a moderate event during the winter months," said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. "But we'll keep our eye on other climate features in the Pacific and the North Atlantic that play an important role on the week-to-week variability in our winter weather. These patterns influence the position of the jet stream and dictate where and how winter storms will move."
During weak to moderate El Niño events, shifts in the jet stream change the patterns of storminess over the eastern North Pacific and North America. "In particular, NOAA anticipates enhanced storminess near the Aleutian Islands and in the Southeast U.S., and warmer, drier conditions over western North America," said Jim Laver, director, NOAA Climate Prediction Center. (Click NOAA image for larger view of forecast winter jetstream, temperature and precipitation outlook for the USA. Click here for high resolution version, which is a large file. Please credit “NOAA.)
Also, the climate system called the North Atlantic Oscillation plays an important role in modulating the winter weather over the eastern half of the U.S. The NAO is a climate pattern that influences the position of the jet stream over the North Atlantic, affecting winter weather over the Northeast.
"To a large extent, our forecast of equal chances of above or below normal temperatures and precipitation over the northeastern U.S. is based on the NAO, which is only confidently predicted one to two weeks in advance," said Ed O'Lenic, meteorologist at the NOAA Climate Prediction Center. Impacts from the NAO are included in the NOAA Climate Prediction Center's 8-14 day and 6-10 day outlooks and U.S. Hazards Assessment.
NOAA continues to improve climate forecasting and push the envelope in understanding the Earth's climate system. For the first time, NOAA's new Climate Forecast System is being used as a tool for this outlook. The Climate Forecast System is a coupled ocean-atmosphere model, which complements other NOAA models and gives increased confidence of probable climate events before they happen.
"NOAA's progress in climate forecasting is based on ongoing research and collaboration with our partners, advancements in our understanding of the global climate system, upgrades to the weather and climate supercomputer, and improvements in the state-of-the-art atmospheric and oceanic modeling applications. The knowledge and understanding NOAA gains is allowing us to begin a new era in climate prediction," said Louis W. Uccellini, director of the NOAA National Centers for Environmental Prediction.
NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nationís coastal and marine resources. NOAA is part of the U.S. Department of Commerce.
Relevant Web Sites
Drought Information Center