Note DetailLa Nina Peak?
3/24/2008 1:58:00 PM

Crop yield risk associated with La Nina is veryreal.  The risk of La Nina remaining a majorfactor in the 2008 weather picture is notclear.  It is possible that the strength of thecurrent episode has peaked (90-day SOI=1.73standard 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