Tuesday 10 a.m.
There's quite a contrast in conditions between Michigan and Massachusetts. At mid-morning, Detroit had some sunshine with south to southwest winds bringing in milder air. Meanwhile, in the I-95 corridor from Boston to Baltimore, dreariness greeted the dawn and dampness lingered. The surface pressure pattern helps explain this. Along the East Coast, the flow is coming from the Atlantic. The isobars bend around over the Appalachians, and the flow west of there is from southwest to northeast. The lines become closer together as you move north through Michigan, and the wind increases to match that. Finally, the isobars at the far upper-left corner of the map peel away from their tight packing and assume more of a west to east orientation. The change occurs along a cold front that will speed to the east and off the New England coast tomorrow night.
This video explores the current situation and how things should progress for the rest of the week and this weekend.
Wet weather is coming toward the Northeast, and episodes of rain may be spread out over a two- to three-day period. Supporting this idea is this satellite/radar image from mid-morning Monday showing pockets and bands of rain affecting several areas.
On this map from 10 a.m. ET Thanksgiving Day, you can see the high pressure area that is causing dry and mild weather in the East and the cold front farther west.
During the late afternoon and early evening hours, the cold front of a knife will slice through the turkey and cause it to accumulate 1-2 inches on plates...
This satellite picture shows clouds over parts New York and Pennsylvania, as well as areas of low clouds, fog and snow cover from Michigan to Illinois. Most of the Northeast should have at least some sunshine through Thanksgiving Day.
As we go through the week, the flow aloft over the East will become southwesterly. This will promote a major warmup. This map shows the projected upper-air flow for Thanksgiving afternoon:
A major snowstorm will affect the area from Iowa to Michigan tonight and tomorrow. At first, snow can melt on streets, but as it continues and the temperature drops, the area impacted by slippery conditions will increase dramatically. This map shows expected accumulations: