Friday 10:40 a.m.
Chilly air is advancing into the Northeast this afternoon, and in many locations, tonight's chill will rival all-time records for the date. That's because the high pressure area marking the center of the chilly air mass will be right over the I95 corridor tomorrow morning, causing clear and calm conditions. Then, once the high moves to the east, a south to southwest flow of warmer air will become established. By Sunday afternoon, temperatures will be in the 60s throughout southern New England and 70 or higher farther south.
Strong thunderstorms from the middle of the country will head toward the western Great Lakes. The severe weather section at accuweather.com can be very helpful in explaining how these storms may affect you.
Tomorrow morning will be chilly in the Middle and North Atlantic states. Sam The Dog seems to like his early trip outside on cold mornings. I think it makes him appreciate the great usefulness of his fur coat.
The surface pressure pattern looks chaotic today, with a multitude of trough lines. A few of these can be caused by glitches in the data, but any of the real ones could be all that's required to organize a short band of showers or thunderstorms. However, these features tend to change character with time, or they disappear and new ones pop up.
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.