Thursday 9 a.m.
Thunderstorms that caused damaging winds in south-central Pennsylvania yesterday afternoon weakened as expected as they approached the I95 corridor. Cooler air follows the front, particularly in the Great Lakes region, where temperatures started the day well down in the 30s. A pocket of cold air aloft helped spawn showers over Wisconsin and Michigan overnight and this morning. In addition to some showers, there could be a thunderstorm at some spots farther east later today.
High pressure will strengthen over the Eastern states tomorrow and Saturday, then probably migrate to a location east of New England later Sunday into early next week. The resulting flow from the ocean can cause low-level moisture to increase, producing clouds and perhaps drizzle or a bit of rain in the Middle Atlantic states (less likely in New England). 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.
With a high pressure area over Maine, a low pressure area over western Indiana and an upper-air storm spinning over the western Great Lakes, the stage is set for wet weather in the Middle and North Atlantic states.
This map is a rainfall forecast from the NWS Middle Atlantic River Forecast Center located in State College, PA.
The upper-air flow forecast for this evening shows the trough that helps to support rainfall ahead of the cold front.
After reaching the 80s today from NYC to Boston, it might not be that warm again through much of next week.
A noticeable push of cooler air will spread southward from Ontario and Quebec into the eastern Great Lakes and New England between tomorrow and Saturday.
A cold front from eastern Canada will slide southward along the East coast between late Friday and the end of the weekend. For the area from Philadelphia to Boston, where temperatures will reach the summery 80s each day through Friday, it will mean a noticeable change to cooler weather.