Note DetailLa Nina Peak?
3/24/2008 2:01:00 PM

Crop yield risk associated with La Nina is very
real.  The risk of La Nina remaining a major factor
in the 2008 weather picture is not clear.  It is
possible that the strength of the current episode
has peaked (90-day SOI=1.73 standard deviations on
13 March 2008).  The diminished deviation since is
not sufficient to define the demise of the La Nina
(much larger deviations have been observed for
events that continued 6 or more additional
months).  The physically related weakening of the
trade winds near the S. American coast line and
accompanying warming of the local sea surface
temperature is an additional sign, as is the daily
value of the SOI that has dipped below 0 for the
first time since mid-January 2008.   I have no data
on how these observations impact the likely hood of
La Nina persistence, but experience tells us that
it bears watching.  The risk of below trend
(150.6 BPA) US Corn Yield is 72% with La Nina and
will diminish to 60% if the La Nina fades before
June arrives.   -- Elwynn --  

Iowa State University Extension