Weather Review and Crop Progress
This report is a summation of the crop and weather conditions that occurred since April 20th as I have been in Michigan getting the family orchard ready for the 2021 growing season. After a cold, cloudy, and damp start to warm season crop planting April 10-21, weather conditions turned warmer, drier and more favorable for planting from April 22-May 9.
Precipitation and temperature anomaly maps for the past 14 days are unavailable due to computer issues on the host’s end. Summary information from the National Center for Environmental Prediction indicated that the northern Plains and Great Lakes region averaged 2-6 F below normal, while the central Plains eastward through central corn belt average normal to 4 F above normal.
Nebraska Agricultural Statistics Service (NASS) reported that 12% of the state’s corn crop had been planted on April 18, behind last year’s pace of 27%, but ahead of the 5-year pace of 16 percent. NASS indicates that as of May 9 corn planting had increased to 71% complete, compared to 76% last year and the 5-year average of 57% complete.
The vast majority of the corn planting remaining lie across the western 1/3 of the state, where delays are tied to a later crop insurance planting date and much cooler temperature conditions compared to eastern Nebraska. This area has also experienced several rounds of frost to hard freeze conditions the past two weeks.
During this same period, dry conditions dominated the northern half of the state, with the majority of precipitation concentrated across the southern 1/3 of Nebraska. NASS reports that 12% of the crop had emerged as of May 9, compared to 27% last year and the 5-year average of 16%. Even though the corn planting pace has jumped 14 points ahead of the 5-year average, emergence is 15 percentage points behind the 5-year average. With warmer temperatures forecast to develop by the second half of this week, this spread should shrink dramatically in next Monday’s NASS crop report.
With corn planting nearly ¾ completed, producers moved to soybean and sorghum planting. NASS reports that 47% of the soybean crop was in the ground on May 9, compared to 51% last year and the 5-year average of 26 percent. On April Since the vast majority of soybeans growing in the state are located across the eastern 1/3 of the state and significant precipitation delays didn’t occur until this past weekend, the percentage of soybeans planted should increase to 70% or higher.
Sorghum planting has begun across the primary growing region south of the I-80 corridor. NASS reports that 6% of the crop was planted as of May 9, compared to 14% last year and the 5-year average of 8 percent. Sorghum planting normally occurs during May when soil temperatures at planting depth move into the 60 F range. With recent rainfall across the southwest and a system currently impacting this region with rainfall, the most likely area for significant planting activity this week will be across south central and southeast Nebraska.
With more favorable planting weather the past two weeks, it is not surprising that soil moisture ratings declined slightly during this period. NASS reported topsoil moisture was 6% very short, 23% short, 68% adequate and 3% surplus. On April 19th NASS reported topsoil was 4% very short, 15% short, 77% adequate and 2% surplus. Very dry conditions across the northern 1/3 of the state (Figure 2) were the likely contributor to the weaker topsoil moisture ratings.
Subsoil moisture ratings have also declined over the past two weeks, although not as significant as the topsoil rating changes. NASS reports that on May 9 8% of the subsoil moisture was rated very short, 23% short, 67% adequate and 2% surplus. On April 18, 5% of the subsoil was rated very short, 28% short, 65% adequate and 2% surplus. Over the past two weeks the very short category increased 3 percentage points, but the short rating increased 5 percentage points and the adequate rating fell 2 percentage points.
Pasture conditions continue to reflect the dryness that has been persistent across western Nebraska for nearly a year. Current pasture rating as of May 9 according to NASS stand at 4% very poor, 12% poor, 36% fair, 43% good and 5% excellent. The areas with the worst pasture rating lie across the Panhandle, extreme northern Nebraska, and portions of southwest Nebraska. Central, east central, southeast, and the eastern half of south central Nebraska currently have had surplus moisture the past 3 month and the majority of 48% of statewide area rated good to excellent lies in this region.
NASS crop ratings for wheat as of May 9 stand at 5% very poor, 12% poor, 42% fair, 37% good, and 4% excellent. Some improvements in these ratings are probable with the next NASS report issued on Monday, primarily from the ongoing precipitation event across the southern Panhandle and southwest Nebraska where 0.50-1.25 inches of moisture are forecast. However, the northern Panhandle will likely miss out on most of this moisture and the crop is likely to deteriorate further.
Weather Outlook
The Climate Prediction Center (CPC) issued their official May temperature and precipitation outlooks April 30th and can be view in Figures 1 and 2. CPC’s temperature outlook calls for above normal temperatures across the southern Great Basin, southern Rockies, southern Plains and the southeastern United States along the Gulf of Mexico. Below normal temperatures are projected for the northwestern Great Lakes. All other areas of the United States have equal chances for above normal, normal, or below normal temperatures, including Nebraska.
CPC’s May precipitation forecast indicates below normal moisture is favored from northern California, east-southeast through the western 1/3 of Texas. A slight bias toward below normal moisture extends northward into the Oklahoma Panhandle, southwestern Kansas and southeastern Colorado. Above normal moisture is forecast for the Great Lakes and Ohio River Valley southward to the Gulf of Mexico and west of the Appalachians. The western periphery extends from central Iowa southwestward to eastern Texas. Equal chances for above normal, normal, or below normal moisture is depicted for the remainder of the country, including Nebraska.
The most recent 3-month temperature and precipitation forecast was issued April 15th for the May-July period calls for above normal temperature nationwide (Figure 3) CPC indicates that below normal precipitation from the Pacific Northwest east-southeast through the southern Plains (Figure 4). The highest probabilities for below normal moisture have been assigned to the Pacific Northwest, the northern half of the Rockies, as well as parts of western South Dakota, Nebraska and Kansas. Above normal moisture is projected for the eastern ¼ of the United States.
It should be noted that the 3-month temperature and precipitation outlooks were issued immediately after the latest La Nina update and immediately following a very warm start to April nationwide. Since the outlook was released, colder than normal conditions have dominated the High Plains region from North Dakota southward through the northern 2/3 of Texas. The strong upper air trough over the Hudson Bay region has keep cool air in place across the northern ½ of the country and subsequently, storm systems have stayed primarily south of the corn belt.
We have had brief glimpses of severe weather here in Nebraska, but no widespread convective outbreaks so far this spring. With strong cooling in place across the northern Plains due to the Hudson Bay upper air trough, severe convection has occurred at the base of this trough position from Kansas/Oklahoma eastward through the middle and lower Mississippi River valley. If numerical models are correct in regards to future weather, this convective activity should begin to impact the central and northern Plains over the next few weeks.
The storm system that dropped rain and snow over eastern Colorado and Wyoming, along with the southern Panhandle and the western half of southwest Nebraska the past two days will shift east of the state by Thursday, May 13th. Zonal to a slight northwest flow aloft will develop to end this week, which brings warmer air to the state. The GFS indicates that a weak wave will move into the northern Plains May 14 and quickly move southeast and strengthen as it moves through eastern Nebraska and western Iowa. Currently, moisture with this system is projected to deliver less than 0.50 inches of moisture.
Normal daily highs should be in the 70’s at this time of the year and the forecast high temperatures are not projected to rise above these levels until the second half of this coming weekend. The warmer conditions projected through this weekend are in response to the GFS model building another significant trough into the central and northern Rockies. This will increase the transport of warm and moist air northward from the Gulf of Mexico. At the same time, pieces of energy will eject out of this trough and increase the potential for scattered thunderstorm activity statewide. Currently, the best chances for widespread moisture are assigned to Kansas and southern Nebraska May 15-16.
The model projects that this trough will slide east of Nebraska May 17th as another upper air trough moves into the Pacific Northwest. The GFS model projects that this trough will deepen and slowly move into the central and northern Rockies by May 20th. High temperatures in advance of this trough are forecast to bring upper 70’s to upper 80 F highs through May 22, before clouds and thunderstorm activity from this upper air low swing into the central Plains.
The GFS model indicates that precipitation with this upper air low will impact western Nebraska May 20-21, before spreading moisture chances eastward May 22-26. Scattered thunderstorms are possible statewide May 23-24, with the model output currently targeting May 25-26 with severe weather across the eastern half of North Dakota southward through Kansas.
A brief lull in storm activity is indicated by the GFS model to occur from May 27-30, before another strong upper air trough moves into the western United States to end the month. Since the projected path of this trough appears to target the northern and central Rockies to begin the month of June, it is likely that thunderstorms and severe weather would develop the first full week of June across the central and northern Plains If the GFS model is correct in its projected movement of this weather system.
Al Dutcher, Agricultural Extension Climatologist, Nebraska State Climate Office