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.
Here's a cool fact: even when Death Valley, California, has a temperature of 110 or 120 degrees, you only have to go up a little more than 3.5 miles to find temperatures at or below freezing.
It appears the dry comfortable air mass now in the Northeast will be replaced by a humid flow from the South Atlantic states for the coming weekend. An upper-air forecast map sequence in the video shows how this could happen. The following map shows the predicted flow from Florida to New Jersey Friday night.
This map shows the pressure analysis for the Northeast and Great Lakes. The gusty flow on the west side of the low pressure area adds a real autumn feel to the air.
Since individual lines and clusters of thunderstorms have limited life spans and change character constantly, forecasting whether it will or won't rain at any one time this weekend is difficult at best. One solution is to have your tablet or phone available with the AccuWeather.com app so you can see where all the storms are at the times when it concerns you the most.
It does look warmer for the weekend, but every time the warm air tries to extend into New England it gets chopped down. There could be more showers at times Sunday and early next week as forest we can tell. If any forecast gives you a headache, why not take a friend's advice: Take two aspen; sequoia in the morning.
This map from 5AM ET shows the cold front that is continuing toward this Northeast and Middle Atlantic states. Temperatures stayed up in the 70s all night ahead of the front but it turned noticeably cooler after the front moved through.