After a week of warm, some would call it hot, and humid weather, the next 7 days are projected to transition to cooler and less humid conditions. The ridge of high pressure that has been in the Gulf of Alaska fairly consistently for the past several months will be reforming after a brief break these past 10 days. This pattern shift will be the principal reason for the changes we will likely be experiencing in the next week.
Although changes are expected, the next couple of days the warm and humid conditions will continue. Thunderstorms, with localized heavy downpours will continue especially today through Saturday. Western North Dakota will be impacted by the cooler weather on Saturday, with all areas experiencing cooler conditions on Sunday. There appears to be a brief shift to warmer temperatures on Monday, before a return to cooler weather again on Tuesday that may last the rest of next week.
These cooler temperature days are projected to generally have maximums in the mid to upper 70s with minimums in the 50s. This will reduce the number of Growing Degree Days (GDDs) over what accumulated over this past week. In addition, with an air mass that originated in Canada frequently in place over the region, it will mean lower atmospheric moisture content in the air (lower dew points) most days. That in combination with less frequent rain episodes (after Saturday) should lead to fewer hours with relative humidity at or above 85% in most locations during this forecast period.
Projected Growing Degree Days, base 34°, 44° and 50° for the period July 16 through July 22, 2015 are presented in Figure 2 and the number of hours expected to be at or above 85% can be found in Figure 3. A return to average or above average temperatures are expected for the end of July.