An Upper Air pattern shift continues on track to bring actual summer-like weather to Southeast Lower Michigan later this weekend. For those who have been waiting for some heat and humidity, this weekend into early next week should bring you some good old fashion summer time weather at times. High temperatures have already popped up well into the 80s recently and there is more heat from where that came from.
Note the shift in the NAO and associated AO (mentioned in the two cool summer months article recently) and what is projected by our ensemble members into mid August. The AO and NAO projections continue to show more of a neutral to positive trend for the near term, which intimates somewhat of a retraction north of the Polar jet that has been so strong this summer, though this could be temporary in nature.
In addition, looking at the resultant 500MB projection for this late weekend shows the broad ridge that has been over the west, moving into the Midwest and Great Lakes. The problem this summer has been that the unusually strong upper low pressure system over central and eastern Canada has been able to flatten any upper high pressure ridges that have been able to progress into the region. For several days now model guidance has been bringing the upper level ridge east (in varying degrees) with the GFS model one of the more aggressive ones.
In addition, check out the projected 6 to 10 day upper level pattern for next week (below) as a broad ridge encompasses much of the central part of the country. Being this upper wind forecast is still quite a ways out, they will be closely watched for its integrity as the time period draws closer .The latest forecast can be attained here.