Note DetailEarly La Nina and Early Winter Extremes
12/28/2008 10:22:00 AM

December weather for most of the United States
(including Alaska and Hawaii) have been extreme and
fundamentally consistent with La Nina conditions.
It is extraordinary for a La Nina to develop this
season of the year (some 3 months earlier that the
La Nina of the past winter).   La Nina peaked in
early March of 2008, contributed to spring
flooding, diminished in Mid-May, and reached an
apparent peak in late November 2008.   The result
has been record snow fall in parts of the American
Northwest, abrupt temperature shifts over much of
the continent, and near record flooding of some
Midwest rivers.  Historically record crests have
been set in January for numerous Midwest Rivers;
however, December crests within the top 10 are
heretofore almost unknown.  The “early peak” of the
current La Nina may indicate that the adverse
impacts with the large-scale event will dissipate
early in the growing season.  If so the above
average moisture in the soils of the Corn Belt
would be considered as advantageous to potential
crop yields.    -- Elwynn --

Iowa State University Extension