Today we flip the calendars to August, the last month of summer meteorologically. You'd think that maybe with the new month, we'd have a new weather pattern. Not the case. We're starting August pretty much the same way we started July - with a trough in the jet stream, and a slow moving closed low. I've attached two images from the GFS computer model's morning run. The first is the jet stream set-up for Sunday. If you click on the image to the left to enlarge it, you'll be able to see a well-defined trough in the jet stream over the Northeastern corner of the country, while there is a distinct ridge of high pressure centered over Oklahoma.
As a result, central portions of the nation, from the Gulf Coast all the way to South Dakota, high temperatures will be in the 90's and 100's this weekend. Therefore, several heat advisories have been issued by the National Weather Service through Sunday or Monday for many of those areas due to the heat and humidity. Back here in the Northeast, and especially in New England, it will be much cooler, with temperatures probably only topping off in the 60's in Northern Maine, 70's elsewhere in New England on both Saturday and Sunday, under mostly cloudy skies with scattered showers and thunderstorms. There could even be some severe thunderstorms in Southern New England on Saturday.
The map to the right is the prediction for Wednesday morning's jet stream. By then, you can see that the trough that will be over the Northeast during the weekend will be gone, and a more "zonal" flow of the jet stream will probably be established. Notice that the big ridge I was talking about of the central parts of the nation this weekend will flatten out as it moves toward the Eastern seaboard. Thus, I am not expecting temperatures in the 90's, but rather temperatures in the lower half of the 80's during the early and middle portions of the next work-week.
It will probably be dry on Monday and Tuesday across much of the Northeast, aside from a few showers in Northern New England on Monday. The next threat of rain does return for later Wednesday though, in the form of scattered showers and thunderstorms.
Have a good weekend!