Tuesday 9 a.m.
Yes, the GFS operational run from yesterday afternoon included a forecast map for the afternoon of Oct. 10 that suggested heavy wet snow would be falling over the higher elevations of central and northern Pennsylvania. That map is below. The output from the same model run 12 hours later shows no such thing... just a Great Lakes low pressure area causing showers with fairly mild temperatures. That map is below the snowy version.
At this point, we cannot put much faith in either idea.
In the shorter range, southwest winds are sponsoring a warmup in the Northeast from today into tomorrow. A cold front will then move though to cause some showers and in places a thunderstorm... followed by cooler air. The front will stall in Virginia or Norrth Carolina, and a low pressure area forming along the front can then bring rain to the Middle Atlantic states on Friday. The video has more.
A storm in the tropical Atlantic is being observed for possible strengthening. This map shows the variety of models purporting to show where the center will go. Most solutions suggest it stays well offshore, but you will notice a few outliers suggesting more threat.
For example, the purple line in the east marks the boundary between air coming in from the ocean and a southwesterly current of warmer air. That boundary was the scene of showers and thunderstorms when it was in the middle of Pennsylvania yesterday, and was associated with rain that moved through the Hudson Valley early this morning.
Looking ahead to late next week, some of the computer models suggest a hurricane could affect areas between the Gulf of Mexico and the Atlantic east of the Bahamas. We are entering the prime part of the Atlantic hurricane season, but at this point there is only one model I am prepared to accept:
The following map shows the individual members of the forecast for the 5,880-meter height line at 500mb. If the 500 mb height is that high, it usually means the weather at the ground in the Northeast is hot. However...
This pressure analysis was made using 9 a.m. ET data. The thin west-east black line is the boundary between hot and cool weather. A low pressure area is moving eastward along the boundary zone, causing showers and thunderstorms. The next low pressure area should send some of the rain farther north.
In the early to middle parts of next week, we expect to see a boundary zone separating hot, humid air to the south from cooler air to the north. A series of ripples or disturbances aloft moving west to east will take turns at enhancing or reducing the chance of showers and thunderstorms.