This video shows how weather systems should progress this week.
The cold front approaching the East shows up quite well in this pressure analysis. Several temperatures are plotted to give you a sense for how much the temperature changes behind the cold front. At Chicago, it went from 60 at 4 a.m. to 39 at 5:19, a 21-degree drop in little more than an hour.
There were tens of thousands of lightning strikes yesterday and last night, as shown on this map:
Last month, we looked at how the polar vortex high in the stratosphere had weakened then reversed to become a high pressure area. In midwinter, that change can signal colder, stormier weather for the Middle and North Atlantic states. This map shows the same high was in place on Sunday evening. This kind of occurrence in spring may not mean as much as it does in midwinter.
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.
Looking beyond next week, we see signs of something that has been missing in the Great Lakes and Northeast just about all summer: hot weather. That may change. Here is a computer model prediction of the upper air flow on Sunday, Aug. 24. Note how the flow appears to run from Arizona all the way to north of New England.
The following regional radar map shows that while there are not any large shields of steady rain, there are pockets and bands of rain and thunderstorms that contain heavy precipitation.