Originally Posted by NOAA
Oct. 12, 2005 — NOAA announced the 2005-2006 U.S. Winter Outlook today for the months December, January and February. NOAA forecasters expect warmer-than-normal temperatures in most of the U.S. The precipitation outlook is less certain, showing equal chances of above, near or below normal precipitation for much of the country. (Click NOAA image for larger view of forecast winter temperatures for the USA. Click here for high resolution version. Please credit “NOAA.)
"Even though the average temperature over the three-month winter season is forecast to be above normal in much of the country, there still will be bouts of winter weather with cold temperatures and frozen precipitation," said retired Navy Vice Admiral Conrad C. Lautenbacher, Jr., Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator.
NOAA does not expect La Niña and El Niño/Southern Oscillation (ENSO) to play a role in this winter's forecast. Without ENSO, forecasters look to other short-term climate factors, like the North Atlantic Oscillation, in determining the overall winter patterns. Under these conditions there tends to be more variability in winter weather patterns across the nation, especially in the Great Lakes region and the northeast U.S.
The 2005-2006 U.S. Winter Outlook calls for warmer-than-normal temperatures across much of the central and western United States, including Alaska and Hawaii. The Midwest, the Southern Californian coast and the East Coast have equal chances of warmer, cooler or near-normal temperatures this winter.
The precipitation outlook calls for wetter-than-normal conditions across most of Arkansas, Louisiana, Oklahoma, and northeastern Texas. Drier-than-normal conditions are expected across the Southwest from Arizona to New Mexico. (Click NOAA image for larger view of forecast winter precipitation for the USA. Click here for high resolution version. Please credit “NOAA.)
As winter approaches, nearly 20 percent of the nation is in some level of drought compared to around 30 percent of the country this time last year as defined by the U.S. Drought Monitor. For the sixth year in a row, drought remains a concern for parts of the Northwest and northern Rockies. Wet or dry conditions during the winter typically have a significant impact on drought conditions. Winter-spring snow pack is particularly important in the West, as much of the annual water supply comes from the springtime snow melt. NOAA cautions it would take a number of significant winter snowstorms to end the drought in the Pacific Northwest and northern Rockies.
What Could Drive This Winter's Weather?
Since early 2005 sea-surface temperatures in the central-equatorial Pacific Ocean have been near normal. Near normal sea-surface temperatures in the central-equatorial Pacific Ocean are expected to continue for the next three to six months. Therefore, it is unlikely that either the El Niño or La Niña phases of the El Niño/Southern Oscillation (ENSO) cycle will be present during the upcoming winter. As a result, one key climate feature that could have a particularly large impact in U.S. winter weather, especially along the East Coast, is the North Atlantic Oscillation or NAO.
The North Atlantic Oscillation often changes its phase from week-to-week. During the positive phase, the jet stream shifts to the north of its usual position and the winter weather features relatively warm days over much of the contiguous U.S. In contrast, during the negative phase the jet stream shifts to the south of its usual position. The negative phase of the NAO features more Nor'easters and more frequent cold air outbreaks and snowstorms, especially along the East Coast. Currently, the phase of the NAO is difficult to anticipate more than one to two weeks in advance.
Recognizing the demand to have more precision with seasonal outlooks, the NOAA Climate Prediction Center has formed a Climate Test Bed. The Climate Test Bed is a collaborative scientific effort among the operational, academic and research communities. The mission of the Climate Test Bed is to accelerate the transfer of atmospheric and oceanic research and development into operational climate forecasts, products and applications. At present the Climate Test Bed is focused on maximizing the use of the NOAA Climate Forecast System model in combination with other climate forecast tools to improve U.S. seasonal precipitation and temperature outlooks.
NOAA will publish updates to the 2005-2006 U.S. Winter Outlook via the Web Oct. 20, and Nov. 17. Meteorological winter begins Dec. 1 while astronomical winter begins Dec. 21.
NOAA, an agency of the U.S. Department of Commerce, 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 nation's coastal and marine resources.
Relevant Web Sites
Climate Factors Helping to Shape Winter 2005-2006
NOAA Climate Prediction Center
NOAA Drought Information Center
El Niño/Southern Oscillation (ENSO) Diagnostic Discussion