Wednesday 8 a.m.
A cold front moving off the East coast is ushering in drier air, and places west of the I95 corridor should have fine weather through Friday. However, closer to the coast, it could be cloudy and wet because the front will stall offshore and a low pressure area may form along it.
Just looking at the morning pressure pattern (see map below the video) and the satellite pictures, it seems the dry air should spread all the way to the coast and the wet weather will all be offshore. However, most computer models show the upper-air winds shifting from westerly to southwesterly along the coast, and they show a band of clouds and rain forming from coastal Virginia to New Jersey and on northeastward through eastern New England.
If that happens, the moisture could easily stay in place on Friday. During the weekend, the next front from the west is likely to cause showers and thunderstorms on Saturday over the Great Lakes and Ohio Valley, with the showery weather heading toward the Middle Atlantic states and New England for Sunday.
(Note, when I just mention "the Northeast," I am referring to the area from Maryland to Maine and out through the eastern Great Lakes. If I think there will be noticeably different weather regimes within that large area, I may use Middle Atlantic states, eastern Great Lakes and/or New York and New England. Admittedly, I can be inconsistent with those descriptions. When you see the video and other pictures, the specific areas I am talking about may be clearer than what you get just from the text.)
Here is today's video:
For now, a northerly flow of drier and cooler air is coming into the the Northeast. However, if the front stalls and a low pressure area forms along it, moisture would return to the area over or east of I95 as early as tomorrow.
October colors scream for attention as summer's emerald draperies are splashed with auburn, set ablaze with firethorn, streaked with burnished copper, then saturated in chocolate just before Halloween.
A weak low pressure area may form along the first cold front as it moves southward and then stalls tomorrow. The map below shows where thunderstorms could break out tomorrow near the eastern Great Lakes. More extensive thunderstorm development is likely with the stronger cold front. That activity is shown in the Plains on this map.
Air comes downhill off the Rockies and warms at a rate of 5.6 degrees F for every thousand feet of descent. The warmed air then continues east. Moisture from the Pacific doesn't make it much past the Rockies and a southerly flow of moist air from over the Gulf of Mexico won't readily reach the northern half of the country. This map shows the flow.
This enhanced infrared satellite picture from midmorning shows the thickest clouds near the Atlantic and Gulf coasts, as well as near the Pacific coast from northern California through Oregon and Washington. Vast areas are dry.
Winds are light from the Interior Northeast out through the Great Lakes region. However, a storm off the North Carolina coast has been generating stronger winds. The difference across the region shows up well in this surface pressure map from 9 a.m. ET. The winds are strongest where the lines (isobars) are closest together.
Typically, late September is in the height of hurricane season. However, things are quiet for the moment. This map by Dan Kottlowski, AccuWeather Hurricane Expert, shows the situation. Keep in mind that the big storm of 2012, Sandy, was still more than a month away on this date two years ago.