Friday 10 a.m.
West to southwest winds are bringing hotter air into the Northeast today. A cold front from eastern Canada will move down the coast tonight and tomorrow. This will make it quite comfortable for most of New England and New York state, but its cooling effect will be less farther south. Meanwhile, moisture from Tropical Rainstorm Isaac is spreading northward through the Mississippi Valley and will then turn eastward. Please check back with us frequently this weekend to see the latest radar information and prospects for rainfall.
This map shows the pressure pattern as of 9 a.m. EDT today. You can see the west to east oriented isobars from northern Indiana and Michigan east to central New England. This is the main current of hot air. Farther north and west, you can see where the isobars bend around. The lines from north of Lake Superior head south to Wisconsin. That's where cooling is taking place now. The southerly and southeasterly flow in the southwest corner of the map shows part of the circulation around Isaac.
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.