Ag Weather Forum

Rain and severe thunderstorms has become an increasing concern for crops across the Canadian Prairies during recent weeks. Reports have included problems for crops, because of excessive moisture, increased disease pressure and hail and wind damage. Damage due to these types of issues is usually of a limited nature.

The conventional wisdom is that more will benefit from adequate rain and the lack of severe heat during July then would be hurt by excessive moisture concerns and severe weather damage. However, for local farms these problems can be fairly dramatic.

As we move through July we look for signs in the upper level wind flow pattern that might hint at a change in the pattern to allow more favorable warmer, drier conditions.

Today's mean maps at the 8-to-10 day time frame do include one such hint. You will note in the included map the moderately size area located along and just off the west coast of Canada indicating above normal heights. This implies a potential for a blocking type ridge.

This ridge is somewhat stronger and larger on the ECMWF view than on the GFS view, but it is indicated on both models. There is a chance that ridging in this area could divert disturbances towards the north as they move in off the Pacific.

The effect would be to diminish the risk of heavy rains in the Canadian Prairies and also to promote somewhat warmer conditions. This would be more of an impact on the Alberta region and less so on Manitoba, as the strong jet stream continues to move northwest to southeast across the region and areas further east would still be subject to occasional chances for thunderstorms even under this pattern.

I would like to point out that even if this ridge forms the history of this pattern during the spring and summer months is to diminish the ridging in favor of the strong jet stream pattern. If history is any guide, I would expect to see a return to the more active weather pattern sooner, rather than later. Hopefully there will be enough warm weather featuring less rainfall to allow improvement in areas now considered too wet. That is, if this, new, drier and warmer period develops at all.

(ES)

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