Wednesday 8:30 a.m.
I've been trying to picture how the changing weather scene will appear in Chicago during the next few days. Today, it's almost like early spring. The temperature started at frosty levels but will head toward 50 this afternoon. Overnight, the temperature will drop through the 30s. Now, since snow, cold and wind have been mentioned as starting tomorrow, the first look outside may give the impression it was all hype. It's been a snowless winter so far, and we wake up Thursday morning and nothing drastic is happening. Then, as we go through the day, it starts to snow. At first, the snow melts because it has been mild and the cooling process will start out slowly. In the afternoon, it gets colder, the snow falls more heavily and we see everything getting covered. The snow hides the thin coating of ice forming underneath. Finally, the wind cranks up tomorrow night. As temperatures fall through the 20s, blinding snow is streaming almost horizontally. Travel becomes an ordeal. Snow on the ground drifts and whips around in little whirlwinds. The wind always makes those curls and twists on windy days, but unless the air is carrying something like leaves, or dust.... or snow... we don't notice it. As the snow continues through Thursday night, you can see it lit up by all the street lights... and the sky even has a tint of orange or red amidst the ocean of falling snow. On Friday, the snow is mostly over, but the wind continues to cause blowing, swirling and drifting. However, the cleanup is underway, and the weekend will be cold, but much less windy.
In Philadelphia and New York City, expect a dose of heavy rain tonight, then a drying trend tomorrow with a hint of spring in the air. On Friday, however, there will be a big change to colder weather. There should be some early showers, perhaps mixing with snow, then gusty winds will tell us that it really is January. One of the computer models transforms an Alberta clipper into a coastal storm on Sunday, but we'll have to examine that situation during the next few days to see whether the picture on screen takes on reality... or not.
In the interior sections of central and northern New England, tomorrow morning will turn quite snowy, and in the mountains and Vermont and New Hampshire the snow will continue at varying rates right through Friday with a foot of new snow quite possible. Will sunsets next week look like this?
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.