Abnormal La Nina plays havoc with weather predictions

Source: Farmtario.com

Farmers are likely to get one more hit of winter before the weather clears up for spring planting.

The polar vortex could be forced back into the middle of North America by another building high pressure system, says Mike McClellan, of Mobile Weather Team Inc., during a recent webinar put on by Great Lakes Grain.

At this point 2021 is looking to be more unsettled than 2020 in southern Ontario.

In 2020 spring was decent, there was moisture in the summer when needed and harvest weather was good for getting off crops.

There are untypical trends in weather moving from 2020 to 2021, says McClellan.

There’s a snow drought in Montana and North Dakota and general dryness across the western U.S.

There’s little snow cover across the Great Plains, which in the past has meant warmer west winds through the main growing areas of the U.S., meaning earlier planting in the corn belt.

The Great Lakes have also had lower ice levels.

The weak La Nina system has affected weather in North America. The trend, which is characterized by cooling in the south Pacific Ocean, pushes trade winds that warms and takes more storms to Asia, and makes South America drier. It often makes North America cooler, but this has been a “very different La Nina”.

That’s partly why this winter was mostly warmer, until a high pressure system finally pushed up to the Gulf of Alaska and drove the polar vortex into the middle of the continent.

There are five or six storm systems around the world following the Jet Stream, says McClellan, and they could bring some active weather during the spring. He expects wetter weather in the Great Lakes area.

“There will be not a lot of early planting, especially if we get a cold snap in the latter part of March and early April,” he said.

If the La Nina stays in a neutral phase McClellan had this forecast for the growing season:

  • There should be enough dry weather for a decent planting season window.
  • June could be a wet month.
  • There will be above-normal temperatures, especially in July and August, with below average precipitation.
  • Harvest will be near normal with slightly above average temperatures and lower precipitation, with increasing precipitation into November.
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