Thursday 10 a.m.
The moist air mass that was over the I-95 corridor yesterday has slipped offshore, and the drier air behind is promoting sunny weather. With the sunshine and a light flow from areas where it is hotter, temperatures will be heading high today through Saturday from Chicago to New York City. A strong low pressure area and cold front will come through the Great Lakes and Northeast later in the weekend. There could be some severe thunderstorms as that front advances. This video shows the basic forecast theme for the next few days.
This 24-hour lightning strike map (8 a.m. yesterday to 8 a.m. today EDT) shows the stunning boundary of the excessive heat wave that is roasting the south-central part of the country. South of the lightning zone, it's just searing sunshine with unrelenting heat. The picture probably contains the lightning strike that sent four people who were sitting under an umbrella at Wildwood, N.J., to the hospital. On a map with this scale, you can't see that one stroke, of course.
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.