Long-term weather forecasts are interesting to chat about, but basing plans on them requires a leap of faith, says Bruce Burnett.
“I’m not a really big believer in these long-term forecasts,” said Burnett, the director of the Canadian Wheat Board’s weather and crop surveillance department.
“Their reliability is not all that spectacular.”
But because markets can move on information from a long-term weather outlook, Burnett monitors four or five forecast sources.
Last week, American wheat prices rose briefly on concerns about delays in the hard red winter wheat harvest and spring wheat planting.
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Burnett finds one- to three-day forecasts most reliable, although less so on precipitation. Five-day forecasts can change dramatically during the forecast period, he said.
Six- to 10-day forecasts can miss the mark, especially when weather patterns are changing rapidly, he said.
Seasonal forecasts suffer from vagueness, said Burnett. A seasonal forecast calling for above-normal precipitation could be neutral if the rain falls at the right time, or devastating if it falls all within two weeks.
It’s important for farmers who watch seasonal forecasts to have some context about what they mean for their farms, said Peter Dzikowski of Alberta Agriculture.
The value of the forecasts is in their interpretation. Dzikowski encourages farmers to keep detailed records of weather conditions on their farms to make better sense of what long-range forecasts could mean for them.
Farmers should consider seasonal predictions as one factor among many going into their decisions, said Rick Lee of the Canadian Institute for Climate Studies in Victoria.
Forecasters look at historical weather data and statistics about the effects of certain weather patterns to come up with their seasonal predictions, said Lee. They tend to have a higher rate of accuracy than they would if they forecast a historical average temperature and precipitation amount.
Lee said people involved in the field 10 years ago would never have thought they could do the seasonal predictions now widely used.
But he said forecasters have success with some locations and some seasons better than others, because the science of long-range forecasting is not yet adequately developed.
But Lee said researchers are starting to make seasonal predictions about wind speed, number of days of bright sunshine and number of days of rain.
It will be some time before they build skill in making these types of predictions, Lee said.
