We've just experienced a tremendous fall weekend weather-wise here in the Bluff City. Cool mornings (41 degrees for an average low at WXLIVE! in Bartlett the past 4 mornings) and pleasant afternoon highs (averaging 71 since last Thursday) have made for a very nice stretch of weather. According to the MWN forecast, that should last another 3 days with dry weather, highs in the lower 70s, and lows a little warmer - in the mid 50s - through Wednesday.
That's when things will change. An upper-level low pressure system will develop at the base (southern end) of a trough now over the Pacific Northwest. By mid-week, that low will strengthen over the Plains and move slowly southeast towards the Mid-Mississippi Valley. The closed low is forecast to affect our region Thursday and Friday (see the image below valid Friday evening and note the concentric black circles and yellow/orange shading over the center of the U.S.). This low will mean plenty of clouds, rain, possibly a few thundershowers, and cooler weather for Thursday and Friday. By Saturday it will pick up speed moving east and we should again see high pressure return for at least the latter half of the weekend and early next week.
The extended range guidance is indicating a more active pattern for late October-early November with below normal temps.