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.
This map shows where Hurricane Joaquin was just before 8 a.m. ET. You can also see the stripe of clouds centered just of the Middle and North Atlantic coasts.
There are competing forces acting on it, and each move it makes will place it under different influences. This has made it very difficult for computer models and meteorologists to judge where it will actually go. This is reflected in the track model collection on this map:
In assessing the final impact of the storm system coming into the East, there are three main components. First is the cold front coming across the Appalachians tonight in a very rich moisture field with ...
On this map, the cold front that will eventually move through the Northeast is in the far northwest corner of the picture. There are areas of showers moving northeastward well ahead of the front, but the steadiest rain is not likely until the cool air moves in and the front stalls.
The Midwest and Northeast are in the latitude zone where winds are primarily from the west. The direct opposite is the case today, as seen on this pressure analysis. The easterly flow brings in moisture from the Atlantic.
The infrared satellite picture below shows the cloudiness as of midmorning on Thursday. If it stays the way it is now, there is no problem in the Northeast. However, on another screen I have been watching the whole area expanding north and west, as indicated on the map.