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Weather Forecast: (06/22/17)

The June 22 through June 28, 2017 Weather Summary/Outlook

You have likely heard about the extreme heat in the southwestern portions of the United States even by their usual hot summer standards. That hot weather is associated with a ridge of high pressure over the western portion of the country which in turn forces the upper-level wind flow to shift to the north or northwest over the northern plains. That type of pattern allows cooler air from central and northern Canada to move into this region. This is why this past week was much cooler than the previous two weeks with temperatures averaging 1° to 3° below average across much of the North Dakota Agricultural Weather Network (NDAWN). Previous to this cool down temperatures were averaging 5° to 10° above average during the first half of June. Temperatures will be getting even cooler over the next several days before a return of more average temperatures toward the middle of next week.

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When you think of “Alberta Clippers” you often think of low pressure systems in the winter with light snow and a brief period of wind. But those winter “clippers” are associated with the same upper-level wind flow from the northwest that we have and will be experiencing in the next week. In the summer similar disturbances, instead of 1-3” of snow, tend to bring pockets of showers and thunderstorms producing under 0.50 inches of rain in the locations that actually get hit. We had such a system yesterday and will have other weak disturbances trigger off showers and thunderstorms in the next week but each event will have widely scattered rain and generally light rain amounts.

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These expected cooler temperatures will mean even fewer growing degree days (GDDs) than last week. Most locations will be recording approximately 20% fewer than last week. The projected GDDs for the next 7 days, Base 32°, 44° and 50° are presented below.

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The high sun angle this time of year in combination with below average air temperatures tends to increase the risk of inversions (warming temperatures with height) to form during the evening and overnight hours. This can cause spray drift problems and also tends to create longer periods with relative humidity above 85% and heavy morning dew on plants. Therefore, high relative humidity hours will rise this week in comparision to what ocurred this past week increasing risk for certain plant diseases.

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Using May 10, 2017 as an average planting date, the number of corn growing degree days accumulated through June 20 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 Other agricultural tools can be found in the applications tab in the menu on the left side of the ndawn.org website. Inversion data can also be found on the NDAWN website in the table section of the current weather link.

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Using a planting date of May 1, 2017, the number of wheat growing degree days accumulated through June 20 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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