Ag Weather Forum

It has always been a little fun for meteorologists to speculate about weather a full season in advance, especially when the landscape is covered in white and temperatures spend most of the time far below freezing.

It is almost amazing that we can move from the current frozen state of the outdoors to fields of green with crops thriving in warm sunshine, but it seems to happen every season, even if there are a few bumps in the road along the way.

Twenty or 30 years ago, long-range forecasts were considered to be a week or maybe 10 days out, with forecasts of a month or more out mostly nothing more than speculation. During the recent two decades, computers have become much faster and more complex, and there has been an increased amount of research into what drives the ocean-atmospheric system around the globe.

This research has included how changes in ocean temperatures in one area of the globe can affect far-removed regions a whole season or longer in the future.

Everyone has become pretty familiar with the term ENSO, which encompasses El Nino and La Nina. There are other such ocean-atmosphere systems in the Atlantic and Indian Oceans that can affect the climates of the land areas of the world. The Pacific Decadal Oscillation or PDO is another index that is on the scale of 30 or 40 years and can affect the large-scale climate across North America.

Climate scientists have slowly been incorporating some of these indexes and data into computer programs or models that run outwards of several months to a year. Most nations have developed their own versions of such models and for the most part these models have varying amounts of success, mostly just a little better than even in skill.

Occasionally these models make a big score when an anomalous pattern develops and it appears that the models do have skill to see unusual warmth, chill, wetness or dryness a few months in advance. The very dry conditions through the U.S. Southern Plains last summer were foreseen as early as late last winter and the very warm month of March 2012 across the eastern half of North America was forecast as early as late January 2012. While these models have yet to be called the gospel, they do seem to have some value in finding fairly extreme events.

The U.S. version of long-range models called the CFSv2 is currently showing a pattern for February much as we have seen so far this winter across the Prairies. Periods of cold or very cold weather are likely for central and eastern areas, with more moderate temperatures west, along with near or a little drier-than-normal levels of precipitation. For spring, the CFSv2 is forecasting somewhat colder-than-normal temperatures across much of Western Canada, including the Prairies. Precipitation for March through May is forecast to be close to normal.

The Canadian version of the long-range models shows a little less cold threat, but does give a greater chance that temperatures may be below normal for February through April. Precipitation forecasts for this same period are given a little better than an even chance of being below normal.

If one were to cross the two models and make a consensus forecast for the next few months, the consensus would imply it to be a little colder and drier than normal for the Prairies. If so, then we may see some delay to the start of the spring planting season and there could be some deficit of soil moisture over time if precipitation continues to be lacking into the spring.

Forecasts this far out are still more exploratory than solid truth, and should be treated with caution. Over the coming years, forecasts months in advance are likely to improve as technology and climate science continue to develop.

Doug Webster can be reached at doug.webster@telventdtn.com

(ES/CZ)

© Copyright 2013 DTN/The Progressive Farmer. All rights reserved.