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Weather Forecast (8/03/17)

The August 3 through August 9, 2017 Weather Summary/Outlook

Temperatures were one to four degrees above average at most North Dakota Agricultural Weather Network (NDAWN) stations in the past week. The one notable exeption was in southeastern North Dakota where temperatures average near or slightly below normal. A significant cool down that began yesterday will continue with the first half of August projected to record below average temperatures.

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There were two main rain events in the past week with both associated with a small cluster of thunderstorms. One occurred last Thursday morning (July 27) from northwestern North Dakota to the south central part of the state. The other was a smaller series of thunderstorms on Monday evening (July 31) that started in the northern Red River Valley and slowly moved southward where it eventually weakened and faded away. Otherwise, much of the week was dry with the central portion of North Dakota recording little to no rainfall. The rain that fell yesterday into this morning (Thursday) is not included in the graphic below.

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The rain that did fall yesterday and that is still likely lingering in some portions of far eastern North Dakota and northwestern Minnesota this morning was associated with a secondary push of cooler air from northern Canada. A weaker cold front moved through the region on Monday night, but a more significant cold front came through in the past 24 hours and is associated with a major weather pattern shift over North America. A large “bubble” of warm air (ridge of high pressure) along the west coast of the United States has developed and is expected to last at least 10 days and possibly longer than that, meaning well below average temperatures on most days for the first half of August. The cooler pattern does not necessarily mean a change in the frequency of rain events, as outside of what fell in the past 36 hours, most days will be dry and what rain does fall is expected to be widely scattered during the next 7 to 10 days.


With temperatures anticipated to be well below average for the time of year during this forecast period, the projected growing degree days (GDDs) will be significantly lower than what was recorded in the past week. The projected GDDs, base 32°, 44° and 50  for the period August 3 through August 9 is presented below.

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With the cool air in place, plus the rainfall from Wednesday and Wednesday night adding to the availability of low level moisture, the number of hours with relative humidity (RH) above 85% is projected to very high in the next seven days. With minimums in the 40s on some mornings you should expected heavy dew on some days that will linger on plants beyond sunrise increasing the risk for plant diseases.

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Using May 10, 2017 as an average planting date, the number of corn growing degree days (Base 50°) accumulated through August 1 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

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Using a planting date of May 1, 2017, the number of wheat growing degree days (Base 32°) accumulated through August 1 is presented 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

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Daryl Ritchison

Meteorologist

Interim Director of the North Dakota Agricultural Weather Network

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