As we near the end of April, it appears that the harsh winter may finally be easing somewhat in the Canadian Prairies. The extreme cold of early April has given way to a more variable temperature pattern. We have seen some above-normal temperatures and, when combined with the normal increase in the length of day and the higher sun angle, this has melted most of the snow cover and begun to warm up the soils.
Precipitation totals during the month have averaged below normal, except in parts of southern Saskatchewan and western and northern Alberta. Precipitation totals during the most recent 60-day period have also averaged below- to well-below normal in Manitoba, northwest areas of Saskatchewan and through much of eastern Alberta. These areas will most likely be able to increase fieldwork and begin planting once the soil temperatures of high enough to allow these activities. However, increasing showers will be needed to ensure favorable germination and early development.
The balance of Saskatchewan has had above and, in some cases, well-above normal precipitation during this period. This added moisture may slow fieldwork for some, but in most cases conditions would be favorable for spring fieldwork, planting and early development after planting.
The short-range forecast covering the timeframe through the first weekend in May indicates a chance for some moderate precipitation in southern growing areas, especially southern Alberta and southern Saskatchewan, during the April 29-to-April 30 timeframe.
This activity might reach to Manitoba as well, but in this area, it may not be enough to make much difference in soil moisture after the very dry fall and winter periods for the area. The variable temperature pattern mentioned is also evident during this period. There will be some colder conditions moving into the eastern Prairies during the April 27-28 weekend, while the west stays warm. Then the west turns cooler while the east warms up April 29-to-April 30. Finally, the region turns cooler during the middle of next week.
The outlook for the first five days of May calls for near- to above-normal temperatures in the west, mostly below normal in the east. Rainfall averages mostly below normal.
For the balance of May, the outlook suggests a drier pattern may continue. Temperatures remain warmer in the west, but still cool east. The La Nina weather pattern in the Pacific continues to weaken and is now near neutral. The high-latitude blocking pattern has also weakened somewhat recently. The upper-level wind pattern during the 10-day period shows above-normal heights and a weak ridge over Western Canada, while the trough has shifted to the east. We still see the polar vortex centered just north to northeast of Hudson Bay in Canada, and it is still expected to be a little stronger than is normal for this time of the year. Finally, high-latitude ridging or ridging located north of this polar vortex that might serve to push the vortex southward is weak and mostly located between the pole and Scandinavia.
The ridge just west of the Prairies crop belt and the northwest flow aloft over the crop area is likely to limit the rainfall chances as long as it holds in the area. Temperatures will be warmer near the ridge, but cooler as we move towards the trough. There remains a strong trough located in the Pacific to the west of the Western Canada ridge, so I am not convinced the ridge will hold in there too long. However, the feeling is that the neutral ENSO picture and storm track still mostly south of the region will keep the Prairies drier than normal for the most part.
This should make for a somewhat more favorable planting season, during May, in most locations. However, it might also leave many locations short on moisture, increasing the risk to germination and early development. This, of course, is dependent on soil temperatures increasing enough to allow for increased fieldwork during the coming weeks.
Joel Burgio can be reached at firstname.lastname@example.org
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