Monday 9 a.m.
A cold front moved through the Northeast during the weekend and has continued to drift south toward the Carolinas. This front has terminated the extreme heat for the time being. Through yesterday, Chicago's July has run more than 12 degrees above average and is only 3 degrees away from what is typical, in San Antonio, Texas.
While the Northeast and Great Lakes face more dry weather, there may be a tendency for moisture to creep northward through the Middle Atlantic states later this week. You can see some hints of that in this video.
Much of the uncertainty later this week is caused by the weakness of the predicted upper air flow. Weak flow means little should change. This means wherever it is raining when the weak flow regime starts could get a lot of rain, but other places won't have any rain at all.
This map shows the weakness of the flow predicted to be over the East (except for northern New England) later this week.
In the Northeast, a high pressure area now in control will be reinforced by another high from northeastern Canada. In the "what could go wrong?" department, a batch of cloudiness has appeared east of New England and has been spreading southwestward toward the New Jersey coast this morning.
The clouds over parts of the region are starting to break up, a sign that the predicted drier air from the northeast is making progress.
Cloudiness covers a large area. A few pockets of clearing show up where south winds ride downhill from mountains to lowlands. Air warms and dries with descent. Notice clearing downwind (northwest of) the Smoky Mts.
So, there could be more showers at times late next week as forest we can tell. For now we are stumped. But, it is our beleaf that this weekend you will like being outside. I know a dogwood. It may be a little cool for the beech, but you can take your dog for walk in the bark. What about next weekend? Don't ax.
If the pattern turns out damp as suggested by this map for Sunday, it could turn gray and drizzly from D.C. to New York City for early next week. If the high does not move offshore and no disturbance approaches from the west, it would be sunny and warm.
Two things stand out: (1) a warmup this weekend and early next week (the top graph), and (2) the overall dryness for the weekend and early next week. This graph is for Philadelphia.