How dry is it?

Weather small-talk is always in season

Small talk in northwest Minnesota has focused since last fall on just how dry it has been. This talk started with the realization that unlike the last couple of years fall 2020 was dry enough to actually complete fall field work. Over the winter, folks wondered how the lack of snow and unseasonably warm temperatures (for the most part) might affect survival of overwintering insect pest. Now come spring, folks are simultaneously glad that spring field operations haven’t been delayed by wet soil conditions and really worried that our soil is too dry for uniform germination and emergence, and activation of soil-applied pre-emergence herbicides. So, I decided to take a look at how fall 2020, winter 2020-2021 and spring 2021 compare to normal. 

NW MN weather data: ACIS

The National Oceanic and Atmospheric Administration’s Regional Climate Centers maintain an Applied Climate Information System (ACIS) database that contains daily precipitation and temperature data gathered by contributors to weather monitoring networks. To see how much drier than normal northwest Minnesota has been, from the ACIS database I chose locations in northwest Minnesota for which both monthly precipitation “normals” (monthly average of accumulated precipitation for the 30 year period from 1990 through 2019) and monthly accumulated precipitation from September 1, 2020 through April 30, 2021 were available. These locations were Georgetown, Twin Valley, the Northwest Research and Outreach Center (NWROC), Goodridge and Hallock in Clay, Norman, Polk, Pennington and Kittson Counties, respectively, and Grand Forks just across the Red River of the North in North Dakota (Figure 1). September through December precipitation totals tend to be wetter than the January through April totals, and so are split into two periods: January through April and September through December.  
 

Figure 1. A map of the weather stations from which data was obtained.

Precipitation data

While not ground-breaking information for those that have paid the least attention to the weather over the last 8 months, the data shows us just how dry it has been (Figure 2). Some locations, such as Goodridge and Twin Valley received less than 50% of normal September 2020 through April 2021 precipitation, while Hallock and Georgetown received just over 50% of normal for that same period. The NWROC and Grand Forks were drier still, receiving less than 1/3 of their normal rainfall for this period. Most of the missed rain at each location was in the September through December time period.

Figure 2. Graphs of accumulated precipitation in September through December and January through April for weather stations in Georgetown, Twin Valley, NWROC, Goodridge and Hallock, MN and Grand Forks, ND. Yellow lines indicate precipitation "normals" (1991-2020) and red lines indicate the accumulated precipitation in fall and winter 2020 and winter and spring 2021.

From May 1 through May 13 the mapped locations received between 0 and 0.35 inches of rain with Georgetown, Twin Valley, NWROC, Grand Forks, Goodridge and Hallock receiving 0, 0.05, 0.16, 0.35, 0.18 and 0.27 inches, respectively (Figure 3).

Figure 3. Accumulated precipitation in Minnesota from May 1 through 13, 2021 (source: Midwest Regional Climate Center).

 

Some of the tough implications of dry soil conditions include uniform crop seed germination and emergence, salt accumulation at the soil surface, erosion of wind-blown soil and delayed activation of pre-emergence herbicides. Look for links to articles regarding some of these issues in the NW MN Cropping Issues newsletter.

Want to help fill in the map on weather data?

This spring, I became one of the volunteers collecting weather data in northwest Minnesota through the Community Collaborative Rain Hail and Snow (CoCoRaHS) network. CoCoRaHS volunteers purchase a program-sanctioned and inexpensive rain gauge that measures rain by the hundredths of an inch (Figure 4). Each day volunteers check and empty their rain gauge and then report daily results either by computer or by using the CoCoRaHS smartphone app.  

Figure 4. CoCoRaHS-sanctioned rain gauge at my house.

All of the data that is collected by volunteers is available for anyone to access. Becoming a monitoring location and monitoring each day are easy to do. Monitoring a rain gauge might make a fun family activity, piquing the interest of kids or grandkids with an interest in weather or farming.