The high pressure area that brought cold air into the Northeast will move straight east. The clockwise flow around the high will create a southerly flow of mild air just in time to cause rain instead of snow in the I-95 corridor. I know this does not bring joy to those who like snow.
I like seeing it better than shoveling it!. When I was growing up, I used to be able to watch snow coming down for hours. The changing flake sizes and temporary increases or decreases in visibility were fascinating (the increases were not enjoyed because it could mean the snow is tapering off). My dad used to ask me why I wanted to see all the snowflakes falling when I could get a much better view of the SAME FLAKES if I would get busy and START SHOVELING!)
In any case, a strengthening low pressure area will probably be centered over or just west of Philadelphia on Wednesday morning, then pass over or west of Boston later in the day. That kind of track will pull very mild air up along the coast, and cities from Philadelphia to Boston would have morning temperatures around 60 on Wednesday. Places in the I-95 corridor could get 1-3 inches of rain. Stream and river levels are relatively low now, but street/highway flooding and stream rises are very likely. After the rain stops, most of the water will run off and drain. However, there can be icy spots and perhaps frozen car door locks Wednesday night.
Even though it will be progressively colder as you move west of the storm track, there will be enough warm air aloft to cause initial snow to mix with or change to rain for a while in Pittsburgh, Syracuse and Rochester (perhaps Buffalo, too). The changeover line will be very important because places that get all snow from a storm like this could get a foot. In the transition zone where it is above freezing aloft and close to freezing at ground level, it will be a very close call on whether or not there is significant icing. Ice makes it hazardous for walking and driving, and any place that gets a real buildup of ice can experience power outages that typically take quite a while to fix. Here is my forecast video.
Here is our preliminary snow forecast map. AccuWeather.com will have stories and updates throughout the Thanksgiving travel period.
A storm strengthening off the Middle Atlantic coast will cause episodes of rain and cool gusty winds from Maryland to Maine. The heaviest rain today is focused on the Washington, D.C., to New York City area. Later tonight and tomorrow, the heaviest rain and strongest winds (gusts of 30-40 mph) should spread northeastward across New England. As the storm slowly departs, the weather will improve from southwest to northeast. This map shows the circulation around the storm as of 9 a.m. ET.
The reason for this is a growing and then stalling storm aloft. This map shows the predicted circulation around the storm on Wednesday evening, showing how the moisture could keep going round and round until the storm leaves.
This mornng, showers were moving across the lower Great Lakes region. A band of thunderstorms developed near Chicago before 6:30 a.m. CT and reached the southwest Michigan shoreline an hour later (8:30 a.m. ET). The following maps show the shower zone and Chicago area lightning.
The tropics have been more active recently. This map shows various entities that area being tracked and analyzed. Hurricane Gonzalo stands out clearly.
A couple of days ago, the storm entering the East had a stronger circulation than it does now. Here is the pressure analysis from earlier this morning. Several minor disturbance can be seen, and trough lines representing those have been sketched on the map. Note that there is little difference in temperature from western Pennsylvania to Wisconsin.
The rain band is only 100-200 miles wide, but it is moving slowly. This map shows its location at 10 a.m. today. Once the main rain band passes, it won't be quite as warm as it was when the rain started. However, by mid-October standard, it will still be mild.