The Southern Plains should prepare for continued drier and warmer
than average weather, while the Pacific Northwest is likely to be
colder and wetter than average from December through February, according
to the annual Winter Outlook released today by NOAA.
For the second winter in a row, La Niña will influence
weather patterns across the country, but as usual, it’s not the only
climate factor at play. The ‘wild card’ is the lesser-known and less
predictable Arctic Oscillation that could produce dramatic short-term
swings in temperatures this winter. NOAA expects La Niña, which returned in August, to gradually
strengthen and continue through the upcoming winter. It is associated
with cooler than normal water temperatures in the tropical Pacific Ocean
and influences weather throughout the world.
“The evolving La Niña will shape this winter,” said Mike
Halpert, deputy director of NOAA’s Climate Prediction Center. “There is
a wild card, though. The erratic Arctic Oscillation can generate
strong shifts in the climate patterns that could overwhelm or amplify
La Niña’s typical impacts.” The Arctic Oscillation is always present and fluctuates
between positive and negative phases. The negative phase of the Arctic
Oscillation pushes cold air into the U.S. from Canada. The Arctic
Oscillation went strongly negative at times the last two winters,
causing outbreaks of cold and snowy conditions in the U.S. such as the
“Snowmaggedon” storm of 2009. Strong Arctic Oscillation episodes
typically last a few weeks and are difficult to predict more than one
to two weeks in advance.
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| Temperature Outlook |
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| Precipitation Outlook |
Highlights of the U.S. Winter Outlook (December through February) include:
- Pacific Northwest:
colder and wetter than average. La Niña often results in below-average
temperatures and increased mountain snow in the Pacific Northwest
and western Montana during the winter months. This may set
the stage for spring flooding in the Missouri River Basin;
- California: colder than average
with odds favoring wetter than average conditions in northern
California and drier than average conditions in southern California.
All of the southern part of the nation are at risk of having
above normal wildfire conditions starting this winter and lasting
into the spring;
- Northern Plains: colder and wetter than average. Spring flooding could be a concern in parts of this region;
- Southern Plains and Gulf Coast States: warmer and drier than average. This will likely exacerbate drought conditions in these regions;
- Florida and south Atlantic Coast: drier
than average, with an equal chance for above-, near-, or
below-normal temperatures. Above normal wildfire conditions;
- Ohio and Tennessee Valleys: wetter than
average with equal chances for above-, near-, or below-average
temperatures. Potential for increased storminess and flooding;
- Northeast and Mid-Atlantic: equal chances
for above-, near-, or below-normal temperatures and
precipitation. Winter weather for these regions is often driven not
by La Niña but by the Arctic Oscillation. If enough cold air and
moisture are in place, areas north of the Ohio Valley and into the
Northeast could see above-average snow;
- Great Lakes: tilt toward colder and wetter than average;
- Hawaii: Above-average temperatures are favored in the western islands with equal
chances of above-, near-, or below average average precipitation.
Statewide, the current drought is expected to continue through
the winter. Drought recovery is more likely over the windward
slopes of the Big Island and Maui;
- Alaska: colder than average over the
southern half of the state and the panhandle with below average
precipitation in the interior eastern part of the state.
Several months ago, I too released my winter weather forecast. The NOAA and I basically only disagree on one point- what will happen in the West.
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| Personal Forecast |
