Crop and Pest Report September 15, 2016

The Autumn Weather Outlook

Traditionally in this space I attempt to give an accurate weather outlook with potential impacts in agriculture for the next 7 days.  As this will be the last Crop and Pest Report for 2016, instead, I will give some of my current thoughts on the weather pattern through the end of October.  Earlier this week (September 13/14) frost (36° or lower) was recorded over a wide portion of North Dakota with several locations even dropping to 32° or lower (Figure 1).  If you are curious, 36° is considered a frost because temperatures are generally recorded at five feet above the surface and often temperatures are a few degrees cooler near the surface, meaning if the 5 foot temperature is 36° there will likely be frost nearer to the ground.   If your area suffered no crop damage from these events, the next threat of frost looks to be holding off until the end of next week (September 23/24).

Figure 1: September 14, 2016 Minimums

The period from September 15 through October 31 has been quite dry the past two harvest seasons, with the exception of far northern North Dakota in 2015 (Figure 2).  That overall dryness in combination with above average temperature lead to some excellent harvest weather.  A commonly asked question is will 2016 make it three in a row?  Although I do not expect these next six weeks to be as warm as either 2014 or 2015 (Figure 3), I do expect above average temperatures during this period in 2016 as well.

The one element of the weather that may be more noticeably different this year is rainfall.  Both 2014 and 2015 for most locations were very dry, near 50% of less of normal rainfall during this period.  Even if Harvest 2016 were to record average rainfall it would seem wet in comparison to the past couple of years and would cause harvest delays.  Plus, considering the big rain event earlier this month hit the same wet areas again with heavy rain and overall the pattern has not shifted that much in the past few months, eastern North Dakota and northwestern Minnesota would favor at least average if not above normal rainfall through October.  Plus, most of my analog years (past years with similar conditions) had between 100-130% of normal precipitation. One storm often is the difference this time of year between too wet or good harvest weather, plus as the old saying goes “timing is everything”, and of course the timing of rain is always important this time of year and those two factors are difficult to forecast long term.

Figure 3 Departure from Average Temperatures Autumn 2015
Figure 2 Percent of Normal Precipitation


Daryl Ritchison