The recent stretch of very low temperatures and snowy weather across the Prairies has some people wondering if spring will ever make its presence known. Now that astronomical spring has come and gone and the days are longer than the nights, can higher temperatures and the beginning of the meltdown be that far behind?
The answer to that question is likely tied to how long the well-established roadblock in the atmosphere across northern Canada and Greenland hangs around. This roadblock is represented by a large upper level high pressure area across areas from Nunavut to Greenland in an area that more times than not this time of year is covered by an area of low pressure or the polar vortex.
Meteorologists call this a blocking pattern because it blocks the normal jet stream flow across Canada and shifts it southward into the U.S. Just like a stone within a stream that deflects the water around it, this upper level high pressure area deflects the jet stream around it.
The upper level high pressure area also helps establish a large and expansive surface high pressure area across Canada which during the winter and early spring helps produce lots of cold air over the extensive snow cover. This cold air covers Canada but also will push southward into the U.S. to meet up with the more southerly jet stream. Storm disturbances moving through the jet stream produce winter weather problems at more southern locations than normal at this time of year.
The Prairies have been in the path of a few of these storms during recent weeks resulting in snow totals already approaching two to three times normal for the entire month of March in some areas. We still have another 10 days remaining in March and another snow event on tap for Friday into Saturday.
A break in the snow is expected for most of next week but not the cold. Temperatures will continue to be quite low for late March next week and the early outlook for April keeps cold weather in place, at least for the first half of the month. With all of the snow already on the ground and the potential of seeing more during the next few weeks, the spring flood potential certainly is high this year.
Temperatures will remain low until the atmospheric roadblock weakens or dissipates. Normally blocking patterns such as we have seen this year don't last more than four to six weeks and we are almost a month into this pattern this year. This blocking pattern is one of the strongest on record for this time of year, so it is possible it may take a little longer than normal to clear.
Implications for the crops this spring would be a delayed start in spring planting and greater-than-normal flood potential.
Doug Webster can be reached at firstname.lastname@example.org
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