KANSAS CITY — Weather pattern changes in the United States during the last week of May promise to bring relief to literally months of moisture and temperature stress that has managed to whittle the size of this year’s high quality hard red winter wheat down considerably. The last week of May will bring on some much needed rain in the central and southern Plains, and whether the rain event is a fluke or not there is likely to be a short-term improvement to small grains produced in the central Plains.

Much of the anticipated rain event in the central and southern Plains will come too late to save this year’s crop entirely. Most of the wheat in Texas and Oklahoma already has advanced too far to bolster yields, but that is not the case in Kansas, Nebraska or Colorado. An improvement in crop quality is still possible in the southern U.S. Plains while yield and quality may be improved in the central Plains.

Mid-May weather in the central and eastern United States was dominated by unseasonably cold temperatures and occasional rain in the Midwest, lower Mississippi River Basin and southeastern states. The rainfall was significant, but not any more so than that which occurs during many spring seasons. Many producers complained about the wet conditions, but it was not really the fault of the rain as much as it was the fault of temperatures.

A very old repeating cycle in the atmosphere has been responsible for the past eight months of colder-than-usual weather. The pattern was expected to lose dominance in the spring of 2014, but it obviously did not. The pattern brought record setting cold to the Plains, Midwest and eastern states during the middle part of May, adding to the problems of hard red winter wheat as well as raising issues with the planting and establishment of spring and summer crops from the northern Plains into the Midwest.

Cold weather has an impact

In hard red winter wheat country, the cold weather had a significant impact, but it was not the first time temperatures turned cold in the Plains. Drought had reached such intensity that desert like characteristics developed in the central and southern Plains. In the desert, relative humidity is so low that temperatures often would rise and fall 30 to 50 degrees Fahrenheit on some days. That kind of a diurnal temperature pattern in the Plains has not occurred, but huge temperature swings did occur from one day to the next. Extreme highs in the 90s to over 100 degrees Fahrenheit occurred on a few occasions during mid-May and just a few days later, after a strong cold front moved through the region, temperatures bottomed out below freezing. That is how some of the wheat crop was damaged.

Damage was reported in late April and during mid-May as this kind of scenario played out across the drought stricken central and southern Plains. Similar surges of cold weather occurred last winter that brought bitter cold temperatures into hard red winter wheat country without much snow on the ground, resulting in some winterkill conditions. More recently the cold occurred while crops were approaching and entering reproduction, which also damaged some of the production potentials.

Finally, in the last week of May there will be a notable switch in weather patterns. The change was expected to bring 10 days of much warmer temperatures and a change in weather patterns so that the water-logged Midwest and lower Mississippi River Basin get a chance to dry out while crop areas in the central and southern Plains get some badly needed rain.

No weather pattern of potential change could have more meaning than that advertised for the central and southern Plains. Most of the southern Plains reported less than half of normal rainfall during the first five months of 2014, and drought has prevailed in many areas since 2010. Some areas have reported dryness dating back even further in time.

Warmer temperatures ahead?

Changes in weather across North America in late May will bring much warmer temperatures to most of the U.S. Plains, Midwest and southeastern states as well as Canada’s Prairies — which also have been quite cold in recent weeks. In addition to those changes, rain will vary significantly across the central and southern Plains with sufficient amounts to offer short-term relief from persistent dryness. The change will bolster topsoil moisture, but for how long?

Drought events that have prevailed as long as this one has will not go away overnight. It will take repetitive rain events over multiple months to restore soil moisture to normal and that will not be an easy task with summer approaching quickly. Rainfall during the typical summer season is not great enough to counter evaporation, and that suggests the rain that falls in late May will be welcome and should bring on some short-term relief from drought, but with temperatures getting to the 80s and 90s Fahrenheit on a more frequent basis in coming weeks most of the moisture will be lost to evaporation.

The hope is that enough rain will fall in late May to lift topsoil moisture in support of better wheat reproductive and filling conditions. The crop cannot fully recover its production potential because of the lateness of the season, but some improved yield potential may occur in Kansas, northern Oklahoma, Colorado and Nebraska. It will be imperative that follow up rain occurs sooner rather than later since the crop only has so many weeks left before the harvest. Hot, dry, weather that evolves in the last days of this month or in June could still reduce some of the potential benefit that will come from the late May rain event.

In the meantime, the same changing weather pattern in the Great Plains also will have influence on other crop areas in the United States and Canada that will be beneficial to many crops. The largest change will be warmer temperatures that will stimulate fast drying rates in the water-logged areas. The heat also will induce a notable rise in soil temperatures and stimulate faster summer crop development rates after inducing accelerated emergence. Rainfall will be reduced across a part of North America in the last days of May, giving some areas a chance to advance more quickly with fieldwork that is long overdue to be completed.

Spring and summer crop planting is well behind average in the northern U.S. Plains, upper Midwest and in both Canada’s Prairies and Ontario’s corn and soybean country. The late May weather pattern change will present “opportunity” to accelerate fieldwork. However, the most important fact about all of the improved weather is that the changes advertised are going to be temporary. The odds are favoring a return to wetter and cooler weather in June, raising more challenges in getting this year’s soybeans and corn planting in the Midwest and the same for canola, wheat, barley, corn, soybeans and other crops in Canada.