The climate crossroads. The place where east meets west and north meets south. Blizzards. Heavy downpours. Heat waves. Damaging hail and tornadic winds. From torrents of rain one year to devastating drought the next. In this unique crossroads of North America lies the Nebraska Sandhills. It is subject to rugged and extreme weather, which could also be said of its inhabitants.
Moisture is a defining climate feature of the region. This unique part of Nebraska is perfectly positioned at the meridian dividing the relatively wet eastern U.S. and the dry intermountain West. In fact, eastern Nebraska receives twice as much annual precipitation as the Panhandle in the West. In a given year, precipitation averages about twenty-three inches in the Sandhills. But does the average ever really mean much? What is often more descriptive is the range of precipitation scenarios. Systematic weather observations began in the late 1800s, and the last century of observations shows precipitation has been greater than thirty inches in some years (34.89 in 1915, 33.05 in 2019, and 31.06 in 2018) and less than fifteen inches in others (12.02 in 2012, 12.79 in 1989, 13.56 in 2002, 13.93 in 1934, 14.32 in 1936, 14.69 in 1974).
Distinct wet and dry seasons characterize the Sandhills. Precipitation is low during the colder months. Thus, from November through February, when snow is common, liquid equivalent precipitation averages about a half inch per month. Precipitation totals start to increase in March, and by May and June, the monthly average is more than three inches. Through the rest of summer and autumn, monthly totals typically start to decline. The driving factor for warm season rain is something called mesoscale convective systems, which is just a fancy term for an organized group of thunderstorms. You might be asking yourself about the source of the water vapor that helps fuel these storms. Part of it is transported all the way from the Gulf of Mexico with the help of southerly winds called a low-level jet. Another part of it is “recycled” and is water from previous rain events that evaporates and adds moisture to the atmosphere.
Historically, snow has occurred in all months of the year, even if just a trace (enough to notice, but not enough to measure) in June through August. February and March are typically the months with the most snow. On average, the region gets about 35 inches per year. Some seasons in recent years have seen more than 50 inches, whereas a few years had 80 to 100 inches. The year 1915 stands out as the wettest year in the Nebraska Sandhills, going back to 1895, and snowfall helped contribute. The observing station at Ainsworth reported a whopping 102 inches that year. In 1984, the area received 83 inches. More recently, the 2018–19 winter had 53 inches, and this snowpack was one of the factors leading to the historic March 2019 flood. Thick river ice, frozen and wet soils, and the trigger of the big storm were the other key factors.
There is a notable trend of increasing precipitation for the Sandhills. Over the last century, this part of Nebraska is gaining about a quarter inch of precipitation per decade. The trend has been amplified in recent decades, and since 1991, precipitation has increased more than an inch per decade. This recent trend is superimposed upon the three driest years on record (2012, 2002, and 1989)—a reflection of increased climate variability. As climate extremes shift so rapidly, this can cause added stressors to management of the area’s precious natural resources.
Drought is a normal part of any climate regime, and the Sandhills is no exception. Whereas drought in general represents a prolonged period of dryness, there are different types, or perspectives, of drought. These perspectives include meteorological, hydrological, agricultural, socioeconomic, and ecological. The primary differences in these types are the impacts, such as low streamflow, crop losses, supply and demand inequities, and ecosystems stress. Many different indicators are used to determine the occurrence of drought. The 1930s was a well-known time of multiyear drought with the detrimental combination of low precipitation and high temperatures. Since then, drought has continued to punctuate the climate record, including the mid-1950s, 1974–76, 1989–90, 2002–3, and 2012. However, these dry years are occurring amid an overall trend toward wetter conditions. When it comes to impacts from drought, one thing to consider is the soil type. Rainfall infiltrates the
sandy soils of this region relatively quickly. Therefore, timely rains are an important factor in grass productivity, as sand doesn’t hold on to water very long. What isn’t taken up by plants (or evaporated) percolates to the shallow water table, near or even above the surface. This aquifer recharge is incredibly important, because irrigation is so widespread and helps to bring previous years’ rain to crops growing in this year’s drought, so to speak. The beautiful native prairie grasses, and the people and animals dependent on them, are impacted most during drought. Thus, water-level declines in the aquifer and in the low-lying wet meadows are significant impacts of drought.
Whereas precipitation is highly variable, wind is most definitely a constant. The direction and intensity may change, but it is usually always blowing. In this part of the Great Plains, some say that the only thing stopping Arctic air is a few barbed wire fences between here and Canada. The typical wind direction during the cold months (roughly November through February) is from a northerly direction, most commonly the northwest. In about March, winds start to shift during the seasonal transition, and southerly winds are just as common. From June through September, it is these warmer winds from the south that are predominant, until seasons change, and we shift back into winter and cold Arctic air.
The average wind speed in the Sandhills is around 10 miles per hour. High wind events can occur any time of year and are typically associated with various types of storms. During the colder time of year, intense winter storms gain strength and speed as they flow out of the Rocky Mountains. Sometimes these storms result in dangerous blizzard conditions, which are the combination of snow and wind causing reduced visibility. Winds higher than 60 miles per hour can occur and are brutal this time of year, due to the resulting low wind chill temperatures. This is especially impactful for Sandhills ranchers, and extra effort is required to keep cattle safe. In warm weather conditions, during what is sometimes called the convective season by meteorologists, the mesoscale convective systems mentioned previously often result in strong straight-line or rotational tornadic winds. These high winds typically impact a smaller area when compared to cold season high winds but are damaging nonetheless. Hail is another common summertime severe weather event, and hailstone can range in size from peas to softballs. The large hail events can be life threatening and damaging to infrastructure and forage production.
As precipitation has a seasonal pattern, so does temperature. The warmest month of the year is July with highs approaching 90 degrees F and lows around 60 degrees F. January is typically the coldest month with highs right around freezing (32°F) and lows around 10 degrees F. For the annual average, temperatures are about 48 degrees F. The warmest year on record was 2012 (51.6°F), while the coldest year was 1951 (44°F). High temperatures can exceed 100 degrees F, although historically these days are fairly rare and occur only a few times in a given year or not at all. The record warm year of 2012 was a notable exception with about two weeks’ worth of extremely hot days. Temperatures below zero are common during winter and occur about twelve days in a given year.
In addition to getting wetter over time, the Sandhills are also getting warmer. Temperatures show an increasing trend over a century-long timespan, warming by about 1.3 degrees F (0.1°F per decade). In recent decades, the warming trend has picked up speed and is 0.3 degree F per decade. Nighttime lows are warming twice as fast as daytime high temperatures, due in part to increasing humidity.
In short, one thing is certain about weather in the Sandhills—day to day, year to year—it’s always changing.