Note DetailRepeat of Past Winter Possible
9/12/2008 5:41:00 AM

Late season precipitation and extremes of winter
temperature and moisture become a consideration for
the Midwest.  The active tropical storm season is
likely to bring significant fall moisture into much
of the Corn Belt.  Additionally the atmospheric
pressure condition of the Pacific Ocean indicates
more than a slight chance of returning to La Nina
conditions that dominated from December to February
of the past winter.    For the Midwest this can
mean additional fall moisture.  By September 12,
2008 some areas that were very dry during the
months of July and August had become wet too late
to aid crop yields and at a time that is
potentially disruptive to harvest.  The SOI
(measure of El Nino / La Nina condition) has
reversed its trend toward El Nino conditions and
during the past 4 weeks has consistently trended
sharply toward La Nina levels.  The 90-day SOI was
measured at 0.52 on September 12, 2008 having
climbed steadily from the 2008 low value of -0.9
observed August 13, 2008.   Under La Nina
conditions the likely hood of unfavorable growing
seasons is increased and the current trend will
likely have a negative impact on the 2009 crop
production risk computations that will be made in
December.        –Elwynn, 12 September 2008 –

Iowa State University Extension