How Dry Is it?

The latest drought monitor map from the UNL Drought Mitigation Center shows 87 percent of the state is under some form of drought. Even more concerning, 43 percent of the state is under a severe, extreme, or exceptional form of drought. While improved from 3 months ago, the drought is still very much on producers’ minds. How does this year’s drought compare to “normal” years and previous droughts, most notably 2012? Tidbits two weeks ago highlighted pasture and range conditions this year compared to 2012. This week, Tidbits looks at subsoil moisture ratings provided by the USDA National Agricultural Statistics Service (NASS) this year compared to the previous 12 years.

Figures 1 and 2 show weekly subsoil moisture ratings in two different forms. Figure 1 plots weekly “very short” subsoil moisture ratings year-to-date compared to 2012 and 2010-2021 average ratings. Ratings are shown beginning with week 13 through week 43, roughly April through October. Very short subsoil moisture ratings averaged between 5-15 percent during those weeks over the 12-year period with the latter half of the growing season being drier than the first half. The extraordinary drought conditions in 2012 definitely stand out with very short ratings reaching 80 percent in late September, well above average. Note the rapid deterioration of moisture conditions beginning in week 24 through week 30 of that year. Unfortunately, this year appears to be on par with 2012 with last week’s subsoil moisture rating (week 26) of 26 percent very short basically at the same level as the 25 percent rating in 2012 for the same week.

Figure 1. Percent Subsoil Rated Very Short of Moisture

The spaghetti-looking Figure 2 shows the same information—the percent of subsoil rated very short of moisture—but instead of plotting the 2010-2021 average it plots the weekly ratings for each year. Note the rarity of very short subsoil moisture ratings in excess of 20 percent. Prior to this year, very short conditions exceeded 20 percent in only four years (2012, 2013, 2017, and 2020). And, prior to this year, 2012 and 2013 were the only years where very short moisture conditions exceeded 35 percent at any time during April-October. Here again, this year is demonstrating similarities to the 2012 drought.

The rapid deterioration in conditions in 2012 from this point forward made it unique and extreme. Rains have fallen in parts of the state recently. Hopefully, the rains continue falling and this year will not be a repeat of 2012.   

Figure 2. Percent of Subsoil Rated Very Short of Moisture (2010-2022)