During the 2020 growing season, Dr. Eric Hunt of Atmospheric and Environmental Research, Inc. will be providing weekly updates of the soil moisture index (SMI) from the Noah-MP land surface model in the NASA LIS framework for the entire U.S. and regional analysis of the SMI over the four regions of U.S. where the majority of corn, soybean, wheat, and cotton production occurs. The analysis is intended to provide the larger agricultural and meteorological communities insight as to areas where soil moisture is excessive or deficient compared to average for that location and what that may mean for impacts. It is my goal that these maps can be an early warning signal for flash drought development or where flash flooding could be likely in the coming week if heavy precipitation materializes. Please be advised that the SMI should be viewed as complementary, not a substitute, to the U.S. Drought Monitor (USDM) and that declarations of drought or flash flood potential for a particular location should never be based on the SMI alone. The Evaporative Stress Index (ESI) is also included in our analysis as are various other maps that help give insight into current conditions across the U.S.
This blog post was partially supported by NASA grant 80NSSC19K1266.
Order of Maps and Tables in today’s Ag Blog
- Figure 1. Soil Moisture Index Panel (U.S., southern Canada, northern Mexico)
- Table 1. Regional Soil Moisture
- Figure 2. SPoRT LIS map
- Figure 3. Soil Moisture Index vs. Corn Trend
- Figure 4. U.S. Drought Monitor
- Figure 5. 2-month Evaporative Stress Index (ESI)
The rain from the Memorial Day holiday weekend and early last week in the western section of the Corn Belt is better reflected in the new maps (Figure 1) and is also reflective of more favorable conditions in the Eastern Corn Belt. As of last Thursday morning, the median SMI in the Corn Belt is at 0.8 (Table 1), which is down from 1.9 last week. With the exception of western Minnesota, most of the region remains favorably moist (Figures 1 and 2). This is good news as the next week is definitely going to abnormally warm from the standpoint of the long-term averages for early June but in line with other warm starts to the climatological summer, which have been much more common in the past decade. Precipitation is expected to be below average over the next ten days but with a warm, relatively humid air mass in place, I suspect some of the western and central Corn Belt will pick up some decent precipitation from a slow-moving cold front that will enter the area later today. Slow moving boundaries can be a focal point for heavy summer precipitation if the air mass is warm and humid, which will be the case for much of the next week over the Corn Belt.
Figure 1. The Soil Moisture Index (SMI) for the 7-day period ending 28 May 2020 (top left) and 14 May 2020 (bottom left). On the right hand side are the grid points where the SMI is at or above 3.0 (top right, red) and grid points where the SMI is at or below 3.0 (bottom right, red). Results are based on output from the 0-1 m (surface to 3.23 feet) layers in the Noah-Multiparameterization (Noah-MP) land surface model. Noah-MP is run in the NASA Land Information System (LIS) framework with the North American Land Data Assimilation Version 2 (NLDAS-2) forcing dataset. The SMI calculation is based on the soil moisture index created in Hunt et al. (2009) such that ‘5’(dark green) is the wettest and ‘-5’ (dark red) the driest for the period of record. The period of record used calculate the SMI for the current map is 1979-present.
Table 1. The regional median SMI value from the current map and the percentage of grid points in the four regions with SMI values greater than 3.0 and less than -3.0. Regions are indicated by the boxes in Figure 1.
Figure 2. 0-100 cm relative wetness from the NASA Short-term Prediction Research and Transition Center (SPoRT) LIS simulation from 00Z on 1 June 2020.
Regardless, the upcoming warm spell isn’t a reason to get bearish about corn and soybean futures just yet as several other years have had warm starts to the summer and finished above trend. The current median SMI of the Corn Belt (0.8) is in well under last year, indicating excessive moisture is not a big problem but is generally adequate enough to sustain crops through some warmer weather. Figure 3 shows that the current regional SMI is line with several other recent seasons (2019 excluded) that finished above trend (blue shaded dots) and that a wet spring isn’t necessarily a good predictor of high yields. It also shows a longer-term trend toward wetter springs as most of the years where the median SMI was below 0.0 going into June were before 1995.
Figure 3. Median soil moisture index (SMI) at Week 22 from 1979-2020 and corn yield trend represented by the colored markers. Categories: Dark Blue > 10%, Blue +6 to 10%, Light Blue +1 to 5%, Gray -1 to 1%, Light Red -1 to -5 %, Red -6 to 10%, Dark Red <-10%.
Elsewhere in the country, there was some improvement across the western portion of Kansas, though the area is still definitely in drought (Fig. 4) and is likely to remain in drought for a while. The Northern Great Plains region is wetter now than a few weeks ago, especially across central Nebraska, where some flooding occurred a week ago. Figures 1 and 2 shows much of the western portion of the Southern Great Plains region is dry, though slightly better than a week ago. Any precipitation now is not likely to have much benefit to the winter wheat crop, though it would be for any later season crops and grasslands in that area.
The southern part of Alabama and the western Florida panhandle remain quite dry, with SMI values mostly below -3.0. Most of the southeast region is neither too wet nor too dry at the present time, which is a good sign going into summer. Any landfalling tropical storms or hurricanes this summer will certainly help keep this region mostly drought-free and help recharge the forested ecosystems that have had their share of drought in the past five years.
Figure 4. U.S. Drought Monitor courtesy of the National Drought Mitigation Center.
The 2-month Evaporative Stress Index (ESI; Figure 4) is not available everywhere in the U.S. yet (out of season mask indicated in white) and at this point of the season, negative values may not necessarily be indicative of drought stress on vegetation. The areas in the U.S. most worth watching are the High Plains of eastern Colorado, Kansas, and the western panhandle of Oklahoma. The western Corn Belt has received adequate to significant precipitation in recent days so concerns there have been eliminated for the time being. Future ESI maps will likely show improvement in Nebraska and Iowa. The Ozarks region of Missouri and the Appalachians of West Virginia will also likely show improvement as well.
The percent of corn planted is on a much better pace than last year, with 93 percent being planted The current percent of corn planted according to the latest USDA Crop Progress Report is above the 5-year average. Most corn (78 percent) has also emerged and 74 percent of corn is rated as good to excellent compared to 4 percent poor or very poor, slight improvements on the numbers from last week. Both numbers are in line with the vast majority of seasons at this point of the year and it should be noted that condition in late May is not a good predictor of final yield. Soybean numbers show 75 percent planted and 52 percent emerged, both of which are above the 5-year averages.
About the author:
Eric Hunt is an agricultural climatologist from Lincoln, NE and has several members of his extended family actively farming in Illinois and Nebraska. Eric has been with AER since 2012 and received his Ph.D. from the University of Nebraska. Among other activities, he is currently working on NASA funded projects to study the evolution of flash drought. He routinely blogs about agriculture and weather on the AER website.
Founded in 1977, Atmospheric and Environmental Research is an award-winning environmental research, consulting and weather information services company with demonstrated expertise in numerical weather prediction, climate dynamics and radiation, circulation diagnostics, atmospheric chemistry, air quality and risk assessment, planetary sciences, remote sensing, satellite meteorology, and systems engineering. Consulting services are available. AER is a business unit of Verisk Analytics (VRSK). For more information, please visit our web site at www.aer.com.
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