Thursday 10:30 a.m.
The high pressure area sponsoring sunny, warm weather in the Northeast now will be replaced by a cooler high pressure area from the Plains for the weekend. Meanwhile, we see a strong jet stream current coming into western Canada. As a ridge builds farther west, the current will be sent southeastward, and this should carve out a strong, chilly trough that will be over the Great Lakes by next Tuesday or Wednesday. Ahead of the strengthening trough, moist air from the Gulf states should flow northward. This could set off an area of significant rainfall between the Ohio Valley and East Coast before the cool air at ground level reaches these places. This video presents the general idea:
This map shows the detailed pressure pattern across the Northeast and Great Lakes this morning. The isobars extending from Kentucky to New York state show the southwesterly flow of warm air. The bend in the isobars (one in Missouri and the other in Michigan) shows the front that separates the warm air from the advancing cooler air. The flow is out of the north across much of Wisconsin.
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.