Author: Michael Ferrari, PhD
VP, Applied Technology & Research

 

While some global La Nina indicators have exhibited a more pronounced shift towards neutral phase, the equatorial Pacific Ocean cold SST anomalies are still pronounced as the above map from Weather Trends shows, and the Southern Oscillation Index is still strongly positive; the March SOI value according to the Australian Bureau of Meteorology was +21.4, down only slightly from the previous month’s value of +22.3 (see chart below).  We note this because many forecasting groups have been discussing a shift to neutral conditions within the next 1-1.5 months, but the risk exists for this transition to take longer, leaving somewhat strong La Nina conditions in place, with the resultant La Nina-related effects for Oceania and Western North America over the next 2-3 months. 

(chart from Australia BOM; maps from NOAA’s Tropical Ocean Atmosphere Project)

 

The two maps above show the stronger anomalies in easterly tradewinds right around 170E – 180; this is also roughly where the eastern edge of of subsurface warm water mass extends, so beyond the surface water temperatures, we will be watching both of these indicators to signal a retreating La Nina pattern.  Nearly all of the dynamical and statistical models in the ensemble of ENSO forecasting models have the La Nina already past the peak intensity period, demonstrating a slow transition to neutral conditions during the April/May/June period.  However, this does not mean that the pattern that has exerted its influence on the Americas (the Southern Plains of the US and much of Argentina in particular) and eastern China, will subside in the near term.

Many commodity analysts are on record as stating that many of the world’s major agriculture belts need ‘perfect weather’ this year, in order to prevent the already high food/raw material costs from spiking even higher; a favorable pattern is also needed to help rebuild stockpiles which are already at low levels.  In addition, while 2011 corn acres are anticipated by USDA to be high, it still may not be enough to satisfy the demand side from both the food and biofuel sectors.  So while there is no such thing as perfect weather, US conditions from planting through germination take on increased significance this year, and the weather sensitivity as expressed through volatility in grains/oilseed futures is likely to reflect this risk.

Please contact Weather Trends International if you wish to discuss further.