Weather Forecast (07/01/21)
Temperatures were close to average if taken as a whole with most stations anywhere from a couple of degrees below average to a couple of degrees above average across the North Dakota Agricultural Weather Network (Figure 1). Last week in this weather summary I had mentioned that if the ridge of high pressure aloft that was attributing to the high heat in the Pacific Northwest were to move into the northern plains, it would probably hold off until the Independence Day weekend. It seems likely that a piece of that heat ridge will build over the region this weekend, with the warmest days being on Friday through Sunday. Monday a few areas may cool down a bit, then next Tuesday and Wednesday all locations are expected to be much cooler. That transition to cooler temperatures next week would also be our best opportunities for rain during this forecast period.
A slow-moving pocket of rain moved from central to northeastern North Dakota last Friday for the most widespread rain during the past week. Several other days recorded some scattered thunderstorms. Total rain from June 24-29, 2021 can found in Figure 2.
Starting this week, I will give an estimated number of hours with relative humidity above 85% because row closer is now occurring with many crops increasing the disease risk. Very few hours of high humidity are expected through the weekend. Most of the hours in Figure 3 are expected to occur next Monday through Wednesday (July 5-7) associated with a slow-moving frontal passage that will bring potential for rain and higher humidity levels.
The projected growing degree days (GDDs) base 32°, 44° and 50° for the period of July 1 through July 7, 2021 can be found in Figure 4. A reminder, that GDDs for most crops do not give credit for temperatures above 86°. In turn, that was the maximum temperature used for these projections. With high temperatures in the 90s for several days this period, most of the differences in Figure 4 are associated with minimum temperatures through Monday and the differences in maximums and minimums thereafter when the temperatures are expected to be noticeably lower.
Using May 1 as a planting date, accumulated growing degree days for wheat (base temperature 32°) is given in Figure 5. You can calculate wheat growing degree days based on your exact planting date(s) here: https://ndawn.ndsu.nodak.edu/wheat-growing-degree-days.html
Using May 10 as a planting date, accumulated growing degree days for corn (base temperature 50°) is given in Figure 6. You can calculate corn growing degree days based on your exact planting date(s) here: https://ndawn.ndsu.nodak.edu/corn-growing-degree-days.html
Soybeans also use base 50° like corn, but NDAWN has a special tool for soybeans that, based on your planting date and cultivar, can estimate maturity dates based on average temperatures, as well as give you GDDs based on your planting date(s) you set. That tool can be found here: https://ndawn.ndsu.nodak.edu/soybean-growing-degree-days.html
Director of the North Dakota Agricultural Weather Network (NDAWN)