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Still working out what La Nina bodes for
northwest spring |
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January 14, 2018 |
Weather Insights are provided by
Northwest
Farm Credit Services by Dr. Eric Snodgrass,
one of the nation's top 40 meteorologists, to
enhance farm production and seasonal planning.
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| Dr. Eric
Snodgrass |
December 2017 was a month of transition. At
times, the flow of the jet stream bowed into a
large ridge that brought well-above-average
temperatures and drier conditions racing north
along the coast. Occasional west winds did bring
in enough precipitation to keep most of
Washington and Idaho near average, but interior
parts of Oregon and Southern Idaho have had a
slight dry bias.
Drought in the Pacific Northwest is largely
confined to Eastern Montana, where drought has
lingered since summer/fall 2017.
Current soil moisture levels are low only in
pockets in the Northwest, but mountain snowpack
is below average through the start of January
for most reporting stations outside of the
mountains in Montana. Winter wheat growers
should note the extremely dry conditions in the
central U.S. This same region has also dealt
with bitterly cold, below 0°F temperatures to
start the new year.
Outside of the U.S., we are watching Russia’s
wheat belt and the growing region near the Black
Sea and Mediterranean. The last 30 days have
been wetter than average for this region while
temperatures have been above normal. Pockets of
very dry conditions have developed late this
fall and winter in China, and parts of Argentina
have been dry, too.
There will be a lot of discussion over the
coming months about the fate of the current La
Niña as spring arrives. Long-range forecasts
project the weak La Niña to move back toward
ENSO-neutral by spring, but it is important to
recognize how big of a player La Niña is in the
Pacific Northwest spring weather.
Historical records show that La Niña has a weak
correlation with cooler March-May temperatures,
but no discernable relationship exists with
spring precipitation in the Northwest. Long-term
trends in temperature and precipitation for the
March-May time period in the Northwest have
trended up slightly in both.
One strong signal in the long-range model runs
by the ECMWF (a.k.a. the European Model) is for
the Northwest to have a wet bias for the
remainder of winter. Most global models are
forecasting an active Pacific branch of the jet
stream, which will continue to bring strong
onshore flow at times to the Northwest which
will improve mountain snowpack.
The first three weeks of January are forecast to
feature a broader ridge at times in the jet
stream, so expect a warm bias over the coming
weeks. However, February and March temperatures
are currently forecast to be much closer to
average.
Dr. Eric Snodgrass is the Director of
Undergraduate Studies for the Department of
Atmospheric Sciences at the University of
Illinois Urbana-Champaign. He serves on numerous
committees and boards on campus, including the
Illinois Teaching Advancement Board, Student
Sustainability Committee and the Provost Task
Force on Improving Large Enrollment Courses. Dr.
Snodgrass' research initiatives focus on K-12
science education as well as weather forecasting
applications in financial markets. |
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