Going into the end of May, dryness is of increasing concern throughout the Canadian Prairies, especially with the recent turn to well-above normal temperatures.
The weather patterns leading to the spring dry pattern have only recently begun to weaken. The strong northeast Canada trough that led to episodes of extreme cold during the winter continued into the early spring. The cold has backed off, as would be expected during late spring, but the northwest flow to the west of this trough kept rain systems far south and east of the Prairies during late April and early May.
The mid-May period saw a further weakening of the trough. As the jet stream lifted north of the area, the growing belt turned hotter. A strong jet stream pattern is typically hotter just south of the jet stream, which in this case was the Canadian Prairies grain belt. We did see some increase in rain during this period as well. A mean trough remained over the northern Rockies and far Western Canada during this time.
Weather systems moving out of the base of the western trough managed, at times, to bring some rain showers to the area. Some have benefited from this activity, but many did not. The rainfall in the region during the most recent 60-day period continues well-below normal. Many areas have experienced less than 40% of the normal rains during this period. This dryness, when combined with recent warmth, has contributed to a rapid planting pace; but at the same time, decreased soil moisture and increased stress to germinating crops.
The weather pattern as it concerns the Prairies during the next week shows some improvement in the rainfall pattern for eastern areas. The mean trough position over the Rockies region of the U.S. has become more active recently, with the typical increase in humidity associated with the spring months. The storm track has lifted far enough to the north to allow rain to reach the southeast part of the Prairies, but there is still too much west-to-east flow to allow this moisture to back up into the western sector of the Prairies during this timeframe. The rainfall in the east should be enough to help germinating crops and early development. However, it is not enough to replenish subsoil moisture. The balance of the region is still drier and much warmer than normal during this period.
The longer-range outlook is more uncertain. We see a trend towards above-normal heights aloft over the central and eastern areas later next week (week of May 27 to June 2) and early in the following week (June 3 to June 9). This likely means that the rainfall will drop off again over the eastern half of the region while showers develop in the west. The mean trough remains in far Western Canada at that time, so there will be some chance for showers. However, these showers should average out below normal. If soil moisture was adequate at this time, this would not be that much of a concern; but, with the current dry soils, this is not a good forecast for crop development, especially in the extended range.
Eastern Canada has had a wet and sometimes very cool spring; southern Ontario especially has been very wet. Some recent drier and warmer conditions have developed. Over the next week, showers and widely variable temperatures are indicated.
The longer-range outlook is somewhat more uncertain. I see a tendency for high pressure ridging in the area, similar to the eastern Prairies. This might mean a more favorable warm and dry weather pattern. However, we continue to see the mean trough over northeast Canada. It is weaker than it has been, but it is still present. If this trough were to dip southward again it could mean an unexpected turn to cooler conditions and probably wetter weather as well.
It appears to me that the Canadian Prairies will continue to experience dry weather concerns and occasional hot weather as well during the late spring and early summer. Rainfall will be below normal. I am cautiously optimistic that the eastern Canada crop belt will see a more favorable weather pattern for spring planting and early development, as rain chances drop off and temperatures trend warmer.
Joel Burgio can be reached at firstname.lastname@example.org
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