Flooding along the Red River in Manitoba is still of much concern as I write this discussion today, especially as a major spring storm will bring heavy snow to the United States portion of the river basin today into Friday. However, I would like to talk a little more about the spring weather pattern at this time.
The Canadian Prairies has had below-normal precipitation over much of the region during the most recent 180-day period, ending April 8. The driest, relative to normal, is over Manitoba, eastern Saskatchewan and south and central Alberta. Large areas within these locations are showing totals only 40 to 60% of normal during this time frame.
Some areas of southwest Manitoba have seen less than 40% of normal precipitation during this period. In general, drier weather during the late-winter and early spring periods would mean conditions would be favorable for early spring fieldwork and planting during the coming weeks. The exception, of course, are areas near the Red River in Manitoba where flooding is expected to occur during this time period. Also, in parts of northern Alberta it might to too wet.
The current weather pattern over North America continues to feature a very strong southern branch jet stream and an active weather pattern in the U.S. This has recently, during the last month or so, featured two significant storm tracks.
The first is in the south-to-east U.S. with episodes of moderate-to-heavy rain hitting the Delta region of the U.S., the southern and eastern Midwest and the middle Atlantic part of the U.S. This storm track is of little concern as it relates to the weather over the Canadian Prairies, except that it ties up available moisture well to the south of the region. The second storm track has been much further north and west. The major storm affecting the north-central part of the U.S. today is an example of this storm track.
There was also another major storm, even a little farther north than this one, about a month ago. This storm track features fewer storms but the ones that have occurred, so far, have been very strong in nature. This storm track is a little more concerning as it relates to the Canadian Prairies weather. Normally, as we move from April to May, storm tracks in the U.S. tend to shift northward with time. If we continue to see an active storm track and it does move north with time, then we could see a dramatic change in the weather pattern in the region, to one featuring more and heavier precipitation.
The included graphic with this discussion shows the mean upper level wind flow maps for the eight- to 10-day period. The most significant aspect of these maps is the trough covering the area from Ontario southward to the lower Mississippi River Valley of the U.S. The jet stream and storm track at that time frame is likely to the south and east of this trough, or in the lower Mississippi River Valley to the east coast states.
The north-to-northwest flow over the eastern Canadian Prairies region west of the trough and the far southern storm track likely means that the chances for significant precipitation to occur in the Prairies region during the next two weeks is rather low. However, as we look upstream from this trough, we first note a flat ridge just off the West Coast of the U.S. and then we see another mean trough located over the Gulf of Alaska. This second trough is likely to send disturbances eastward into the west-central areas of North America, north of the flat ridge off the east coast. These disturbances will need to be watched. Strong short wave troughs moving into the U.S. or Western Canada will tend to intensify as they drop into the mean trough position. I do not see any indication, at this time, that this means a significant precipitation event for the Canadian Prairies or even the Northern Plains of the U.S. However, this is something that would be difficult to pick up on more than a couple of weeks ahead of time.
The late winter and early spring weather patterns have allowed for less snow cover and drier soils across much of the Canadian Prairies. The forecasted weather patterns during the middle to the late part of April suggests that this pattern is unlikely to change soon. This likely means that outside of the flooding near the Red River and possibly through the northern Alberta region, the prospects for favorable conditions for early spring fieldwork look good. However, this pattern is volatile and will need to be watched going forward.
Joel Burgio can be reached at email@example.com
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