Wednesday 10:30 a.m.
Today's Northeast video shows how the coming storm system should move and what its effects will be along the way. With such an energetic trough crossing a region with plenty of moisture and a large contrast in temperature, heavy rain will be common north of the storm track, and violent thunderstorms will be to the south.
This map shows the low pressure at the western edge. The isobars help define the location of the frontal boundary between the hot and cool air masses. Note how widely spaced these lines are in the middle of the map. In this area, the exact boundary is difficult to determine.
Please follow the unfolding storm situation with our stories and frequent videos (because this report is usually not updated).
I will be out of the office from Friday until the end of the month. I may post occasionally during the vacation.
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.