The September 14 through September 20, 2017 Weather Summary/Outlook
Temperatures so far this month have been running above average across most of the North Dakota Agricultural Weather Network (NDAWN). Much of this is due to the well above normal temperatures of the past few days as the first week of September temperatures were mostly below normal. The recent warmth is about to end, as beginning today (Thursday) we will be trending cooler and by this weekend temperatures will be 10° to 20° below average. In fact, on Saturday, some parts of the region may record maximums only in the upper 40s.
Our recent warm weather has come with no moisture as the rain that has fallen so far in September at some NDAWN stations occurred during the cooler weather earlier in the month. Rain is expected with the transition to cooler temperatures in the next several days. There will be at least some scattered precipitation in the area today, but a more widespread rain event is expected on Friday with some lingering lighter rain during the weekend.
Most of this growing season the upper level wind flow has been out of the northwest, meaning a flow from Canada. This flow does not allow for much moisture to be advected into the northern plains from the Gulf of Mexico and in turn, the dry conditions that most of North Dakota and northwestern Minnesota recorded this summer. The storm system expected in the next couple of days will come in from a more southwesterly direction. It is storms along that track that have historically brought the most abundant moisture, meaning that although not everyone will get the same amount of rainfall, there is much more potential for a more widespread rain in the next couple of days than we have experienced most of this year.
The projected growing degree days (GDDs), base 32°, 44° and 50 for the period September 14 through September 20 is presented below.
The very cool August has push maturity of corn and soybeans in particular behind schedule. Using GDDs based 50° the graphic below shows that many parts of eastern North Dakota and northwestern Minnesota are 200 to 300 GDDs behind the pace of last year. The coolness of the next several days will come with very few GDDs, but some warming is expected toward the middle of next week with maximums in the 80s for a least a couple of days.
Using May 10, 2017 as an average planting date, the number of corn growing degree days (Base 50°) accumulated through September 12 is depicted below. The exact numbers based on your actual planting date(s) can be found here: https://ndawn.ndsu.nodak.edu/corn-growing-degree-days.html
Using a planting date of May 1, 2017, the number of wheat growing degree days (Base 32°) accumulated this season through September 12 is given below. The exact numbers based on your actual planting date(s) can be found here: https://ndawn.ndsu.nodak.edu/wheat-growing-degree-days.html