Thursday 11:15 a.m.
Here is today's video. In addition to showing today's cold front, there is an emphasis on the storm threat for the Northeast Sunday night and Monday. Since that storm is not coming for at least three days, there are many things that can change. In a north to south distance of about 125 miles, storm can cause anything from a foot of snow with temperatures in the 20s to an inch of rain with readings in the 40s. There will be dangerous ice in the transition zone.
This map shows the pressure pattern at 10 a.m. A cold front can be identified by the change in curvature of the isobars. This change is easiest to see nearest the northern and southern ends of the front.
On this radar picture, you can see a line of snow squalls. These are possible from eastern Pennsylvania through New England this afternoon. They don't last long, but historically, this is the kind of setup that causes serious multiple vehicle accidents.
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.