A favorable spring weather pattern is expected in 2021 for many US crop areas from the Plains into the Midwest and lower Mississippi River Basin. Timely precipitation events are expected that will maintain moisture abundance in the heart of the Midwest and northern Delta and some timely rainfall is expected to ease dryness in the northern and western Plains.
However, the fixes in dry areas of the US northern Plains and Canada’s southern Prairies may be short-lived with returning dryness expected during the summer, especially July and August. That puts much pressure on the significance of spring rainfall in the already dry areas of the northern Plains and southern Canada’s Prairies.
Finally, the record-setting cold arctic airmass of late has abated. The good news is that we will not be that cold again in this winter, and if it is like past episodes of extreme cold we may not see it for a few years. Unless, of course, we experience another year of La Niña and drought prevails in a part of North America. Then the potential for another cold winter in 2022 becomes viable once again.
Worry about another winter before the spring crops are planted is not the issue for this article, but World Weather, Inc. will be returning to that premise a little later this year. For now, the reason for mentioning the abating arctic airmass is the associated change in atmospheric conditions that will now follow.
A frequent succession of storm systems will be moving through the northwestern United States and slipping through the Great Basin to the southern Rocky Mountains and then into the central Plains. The storms will turn to the east northeast, from there passing through the heart of the Midwest and into the northeastern United States. That will be the storm track during March and April with some short-term disruptions brought on by additional “seasonably cool” air masses dropping into the heart of North America from the northwest.
These two weather patterns will dominate into the heart of spring and as time moves along and seasonal warming takes place the storm tracks will shift northward. March and April weather will bring precipitation events frequently to the Midwest and northeastern US as well as southeastern Canada after beginning in parts of the central Plains. As time moves along in April and May the pattern will shift northward with storm systems bringing some needed moisture to the northern Plains, upper Midwest and Canada’s Prairies.
This expected spring pattern will be extremely important since most of the western half of North America is still experiencing drought. Dryness in the northern Plains and Canada’s southern and eastern Prairies is serious enough to worry many producers over wheat, barley and canola plantings as well as the late season crops like corn, soybeans, flax and sunseed. Getting significant relief to these dry areas in the next few weeks is imperative to support spring planting and to reduce the impact of late-summer dryness that is expected to evolve in these areas. Relief is likely and sufficient moisture should occur to produce favorable planting conditions.
In the meantime, a mini-ridge of high pressure will develop over the southeastern corner of the United States this spring, drying out the water-logged southeastern corner of the nation. But, that too will be temporary with another wet finish to the summer expected there as well. The western United States will see some of its dryness whittled down in the next few weeks and that will prove to be very important, but lingering La Niña conditions and some ocean cooling off the West Coast of North America will be a concern for support of a possible stronger ridge of high pressure in the middle of North America this summer.
There is support for returning dryness in the northern Plains and northern Midwest this summer as well as Canada’s southeastern Prairies. This bias shows up in the 18-year cycle data as well as in highly correlated years of weakening La Niña. Research in past La Niña events reveals dryness to some degree in the middle of the United States regardless of its intensity. However, a stronger biased La Niña event builds a strong ridge of high pressure in the middle of North America and can bring on stressful summer crop development conditions in the Plains and western Corn Belt. Further research has revealed that La Niña events that weaken from moderately strong events in January to marginal events during the early summer tend to support dryness in the northern Plains, northern Midwest and southern Canada’s Prairies more than areas to the south.
Many computer forecast models suggest this La Niña will steadily weaken over the next few weeks and it will become a minimal event in April. A few of those forecast models have suggested La Niña will then intensify during the summer.
World Weather, Inc. believes the intensification of La Niña is more likely to come at the end of summer and into the autumn, which raises the potential for dryness during the heart of summer in the northern Plains, upper Midwest and southeastern Canada’s Prairies followed by expanding dryness at the end of the summer — mostly in September into a larger part of the US Plains and Midwest.
Predicting La Niña for late summer and autumn is very risky this far in advance, but if we just stay focused on the heart of the growing season we must come to the conclusion summer will be most drier biased in the north-central US states and neighboring areas of Canada, although some other pockets of dryness will be around in the United States as well.
In the meantime, there is some potential for the water-logged southeastern states to experience a moisture shortage for a little while during the second half of spring and early summer before good late-season rainfall evolves.
If the advertised scenario plays out planting conditions in the dry northern Plains and southern and eastern Canada’s Prairies will improve this spring, and early season crops will get off to a good start. Dryness that evolves during the summer could threaten late-season crops more than small grains and canola, but they all could be at risk if the spring rain is not as good as expected and dryness comes along a little too soon. The lower and eastern Midwest crops may do well this year as long as La Niña does not intensify too soon. The southeastern states will experience improved planting weather early this spring (March and early April, but could become a little too dry in late spring before improved late summer rainfall evolves. The lower Mississippi River Basin could get caught up in some of the spring dryness if the southeastern US ridge of high pressure is too broad based and strong.
As for hard red winter wheat and other crop areas in the central and southern Plains, there will be some timely spring precipitation, but a full restoration in soil moisture may not occur and summer heat and dryness could bring on crop stress especially if La Niña is stronger than expected.