Crop and Pest Report Weather Outlook for 7/28/16

A ridge of high pressure currently over the Pacific Northwest has adjusted the upper level wind flow over the northern plains.  Currently, the flow is from the northwest and this will continue to allow cooler Canadian air to dominate our weather for a couple of more days.  Western North Dakota will start recording warmer temperatures on Saturday, but eastern North Dakota will continue on the cool side until Sunday afternoon.  The warmer temperatures this weekend into the middle of next week will be associated with that ridge of high pressure to our west moving slowly over our region this weekend into the middle of next week.  This will bring back average to even slightly above average temperatures to the region.

Current 500 mb heights/anomalies

Current 500 mb heights/anomalies

Projected 500 mb heights/anomalies for 00Z Wednesday August 3 (7 pm CDT Tuesday)

Projected 500 mb heights/anomalies for 00Z Wednesday August 3 (7 pm CDT Tuesday)

 

Maximum temperatures in the 90s are foreseen on Sunday afternoon in western North Dakota and certainly a few other days the maximums may be near 90° in other locations throughout North Dakota into northwestern Minnesota.  Yet, the upcoming period of warmer temperatures does not look as warm, nor as humid, as the last surge of warm air from earlier this week into late last week.  This will mean fewer hours of relative humidity (RH) values above 85% as were recorded this past week (Figure 1).  Plus, with this period starting cool and with the expected upcoming warmth not being as extreme as what we recorded in the middle of July, these next seven days are expected to record about 10% fewer growing degree days (GDDs) than we measured in the past week.

Precipitation is expected to be either non-existent or not very widespread for the next few days.  With the cooler air from Canada also comes in drier air, meaning the wet locations will have an opportunity to dry off in the short term.  It does appear as the next surge of warmer air moves in, that the upper-level wind flow will transition to a southwesterly direction ushering in thunderstorms early next week (Sunday night into Monday Night).  Then there will probably be another threat of rain toward the middle of next week (late Wednesday/Thursday, August 3,4) as a period of cooler air moves back into the region.  Beyond this period there are indications that a warmer and drier pattern will emerge as we move toward the middle of August.  Meaning, there is still plenty of summer ahead of us.

Projected Hours with Relative Humidity above 85% from July 28 through August 3, 2016

Figure 1. Projected Hours with Relative Humidity above 85% from July 28 through August 3, 2016

 

Projected Growing Degree Days Base 50, 44 and 32 for the period July 28 through August 3, 2016

Figure 2: Projected Growing Degree Days Base 50, 44 and 32 for the period July 28 through August 3, 2016

Daryl Ritchison

 

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