October 17, 2003
The forecast also projected the multi-year drought in the West will likely continue with limited improvement and lingering water shortages. The winter outlook will be updated on Nov. 20.
Reasons for Uncertainty
"Without a strong El Niño or La Niña signal as a guide, there is more uncertainty in our forecast, but we do expect winter to bring its typical weather variability," said John Jones, Jr., deputy director of NOAA's National Weather Service.
He added that forecasters, in cases where a dominant climate feature in the Pacific Ocean is missing, rely on historical trends of temperature and precipitation averages as well as dynamical and statistical models.
Jones said researchers are studying other climatic factors that influence NOAA's seasonal outlooks, but these influences aren't yet routinely predictable on seasonal time scales. As examples, he cited several factors that need further study and pose significant challenges to the climate forecast, including: tropical ocean temperatures in the western Pacific and Indian Oceans, atmospheric circulation patterns in the Arctic and North Atlantic, snow cover in the high latitudes during the late fall and U.S. soil moisture conditions.
"There is a need to continue collaborating with the research community, for improving data management and collection operations, and fine-tuning the oceanic and atmospheric models that run on the supercomputers," Jones said. "Forecast uncertainty in low climate signal years like this can be reduced, but it will take more research and more resources to do that."
Jones said the conditions this year also highlight the value of collecting and sharing data on a global scale. NOAA is moving aggressively on that front with action that came out of the Administration-sponsored Earth Observation Summit that was held this summer in Washington, D.C. At that session, more than 34 nations plus the European Commission launched the development of a 10-year implementation plan to arrange a system of integrated space-borne, airborne and in situ observations to help understand and address global environmental and economic concerns. NOAA, NASA and the U.S. State Department hosted the summit.
Winter 2003-04 Outlook
"While ocean temperatures in the tropical Pacific are warmer than long-term averages, and may even reach the level of a weak El Niño by late November, El Niño is not expected to exert a major influence on U.S. climate this winter," said Ed O'Lenic, senior meteorologist and lead forecaster at NOAA's Climate Prediction Center, which is part of NOAA's National Weather Service. "Our forecast tools imply large uncertainty in the northern and eastern U.S., while a clearer picture emerges elsewhere."
Based on those tools, NOAA forecasters expect:
NOAA forecasters also expect existing multi-year drought conditions in the much of the West (except California) and parts of the Central Plains to continue with improvement in complex patterns predominantly in the north central plains and parts of the far west. In most other areas drought will likely persist or improve with many lingering, long-term water shortages.
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