Delightful midweek air with plenty of sun, before showers move in again

Amazingly, as a dome of exceptional heat becomes the nation’s main weather headline for the next few days, New England will remain entirely removed from hot temperatures. 

The reason is the jet stream – the fast river of air, flowing at high altitudes, that steers storms and separates cool air to the north from hot to the south – taking a southern dip, called a “trough,” over the Northeast. This allows cool air from Canada to pour south into New England, and cuts the heat off at the pass, keeping dangerous heat index values up to 115 degrees over the nation’s midsection and as far north as the Canada border, but west of New England. 

Instead, Wednesday brings another day of low humidity and tons of sunshine, with a very high ultraviolet index about the only culprit to be aware of when it comes to sunburns – otherwise, with fresh, clean air and comfortable temperatures in a light onshore breeze, the weather remains very easy going. The relaxed weather includes for beachgoers and mariners, with a one to two foot sea relaxing as the wind quiets even more late in the day. 

Clear sky and dry air will contribute to another cool night Wednesday night with widespread lows in the 50s and some pockets of 40s in sheltered valleys. Thursday will dawn with sunshine ahead of increasing clouds Thursday afternoon as a ribbon of showers – developing on the battle zone between cool and hot air nudging east through Upstate New York and into western New England Thursday afternoon and eastern New England by Thursday evening and night. 

Once the showers arrive to New England, they’ll last awhile, with off and on showers and periods of rain expected Friday as noticeably more humid air arrives, concurrent with a jet stream disturbance aloft. The humid feeling will very likely last into the weekend, with enough moisture in the air for a follow-up disturbance Saturday to touch off scattered showers and thunder at times, starting as soon as morning in northern New England and mostly in the afternoon for the southern half of New England. 

Even Sunday, as humidity lowers and disturbances aloft ease, a few showers still may pop up, particularly during the afternoon, though each day after Friday features noticeable improvement, leading into a nice start to next week.  The tropics will remain active, with now-Tropical Storm Franklin expected to intensify to a hurricane south of Bermuda by early next week, but as long as we continue seeing northern jet stream disturbances and surface cold fronts here in New England, the threat from tropical systems remains suppressed over the next several days.  Instead, we see the potential for some midweek showers next week then, perhaps a bit ironically, the potential for warmth to return as we start the new month of September.