[OCT. 14, 2005]
WASHINGTON --
On Wednesday the National Oceanic and Atmospheric Administration
announced the U.S. winter outlook 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.
"Even though the average temperature over the three-month winter
season is forecast to be above normal in much of the country, there
will still be bouts of winter weather with cold temperatures and
frozen precipitation," said retired Navy Vice Admiral Conrad C.
Lautenbacher Jr., Ph.D., under secretary of commerce for oceans and
atmosphere and NOAA administrator.
NOAA does not expect La Niņa and El Niņo- Southern Oscillation to
play a role in this winter's forecast, so 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
northeastern U.S.
The outlook
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 California
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.
As winter approaches, nearly 20 percent of the nation is in some
level of drought, compared with 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 effect on drought conditions.
Winter-spring snowpack is particularly important in the West, as
much of the annual water supply comes from the springtime snowmelt.
NOAA cautions that 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 Niņo or La Niņa phases of the El Niņo-Southern Oscillation cycle will be present during the upcoming
winter. As a result, one key climate feature that could have a
particularly large effect on U.S. winter weather, especially along
the East Coast, is the North Atlantic Oscillation.
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 oscillation features more
nor'easters and more frequent cold air outbreaks and snowstorms,
especially along the East Coast. Currently, the phase of the
oscillation is difficult to anticipate more than one to two weeks in
advance.
Recognizing the demand to have more precision with
seasonal outlooks, NOAA's Climate Prediction Center has formed a
Climate Test Bed, a collaborative scientific effort among the
operational, academic and research communities. Their mission is to
accelerate the transfer of atmospheric and oceanic research and
development into operational climate forecasts, products and
applications. At present the collaborative effort is focused on
maximizing the use of NOAA's 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 winter outlook via the Web on
Oct. 20 and Nov. 17. Meteorological winter begins Dec. 1, while
astronomical winter begins Dec. 21.
The National Oceanic and Atmospheric Administration, an agency of
the U.S. Commerce Department, 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 our nation's coastal and marine resources. Through
the emerging Global Earth Observation System of Systems, the agency
is working with its federal partners and nearly 60 countries to
develop a global monitoring network that is as integrated as the
planet it observes.
