After an incredible late spring and early summer stretch of weather, days like today have become harder to come by in July – sunshine and temperatures well into the 80s and pushing 90°. A flow of air thousands of feet above our heads, driven by the jet stream steering winds aloft, is flowing from western Canada to the Great Lakes and New England, carrying three features that will impact our forecast: energetic disturbances, cooler air and wildfire smoke. The wildfire smoke is the first and most apparent impact on New England’s sky Tuesday, carried east from wildfires in the Western US and Western Canada, thousands of feet aloft, the smoke will both add a haze to the Tuesday sky and provide some extra color to sunset Tuesday. The energetic disturbances caught in the flow of west and northwest wind aloft are set to arrive to New England Tuesday afternoon, raising the risk of showers and thunder – some possibly strong - in Northern and Western New England. Although Southern New and Eastern New England are far less likely to find Tuesday afternoon storms, an isolated shower can’t be ruled out in Eastern MA Tuesday afternoon, then the storms of Northern and Western areas may carry south and east while slowly weakening late Tuesday evening and overnight Tuesday night. Aside from the isolated showers, mariners will find a delightful Tuesday on the water with a nearly calm sea and very light wind. Changing weather Wednesday will be marked by a slow-moving cold front that will deliver occasional showers to Northern New England over much of the day, and afternoon through evening downpours and thunder to Southern New England, where damaging wind gusts and localized flash flooding will be possible given the expected strength of the storms. New air streams into New England by Thursday, lowering humidity dramatically and bringing fair and delightful weather. One quick-moving disturbance raises the chance of a passing shower slightly Friday before another shot of comfortable air with a fair sky to make Saturday the pick of the weekend. The unfortunate by-product of cool and comfortable air is, eventually, warmth and humidity returns this time of the year and when that happens, a collision of air means an increased chance of clouds, showers and rain. Right now, it looks like that transition from nice weather to showers happens from Saturday (nice) to Sunday (cloudy, showery). The chance of showers remains elevated into early next week but the weather pattern may start to move a little faster, with a day or so of spacing between shower chances by the way it looks right now in our exclusive First Alert 10-day forecast.
We're coming off a Sunday evening tornado touchdown in Somers, Connecticut, and although more showers, downpours and thunder will fall on a waterlogged New England region Monday, available energy in the atmosphere is less than in recent days, meaning flash flooding and severe weather are both much less likely. Our First Alert Team can’t say the threat for flash flooding is non-existent given the saturated ground, but conditions are less favorable for intense thunderstorms. The best weather Monday is found at the corners of New England: Northern ME, Northwest VT and the South Coast, all of which will see the most sun and fewest showers, while early fog to lots of clouds dominates for the rest of us. Showers will wane Monday night with clearing expected around and after midnight, save for some patchy fog, and this should result in sunshine Tuesday! With ample sun much of the day, high temperatures Tuesday will reach to between 85 and 90 degrees as continued humid air produces a heat index value of 90 to 95 for some, particularly in Southern New England. Although the number of late day and evening storms may be limited, Tuesday’s heat and humidity will provide fuel for storms that do develop, meaning some severe storms are possible during the late day and evening well ahead of a slow-moving cold front approaching from Canada. That same slow-moving front crosses New England on Wednesday, fueling multiple showers and thunderstorms, strongest during the afternoon, raising the risk for at least some severe weather and, moreover, for pockets of renewed flash flooding if recent recipients of heaviest rainfall are hit again. The good news comes behind Wednesday’s storms: less humid, comfortable air for a great Thursday. Friday may bring some showers with a disturbance aloft, but our forecast calls for comfortable air Saturday, which is likely to be the best day of the weekend. The problem with our nicer weather at the end of the week into Saturday is it’s coming courtesy of cooler, drier Canadian air – the reason that poses a problem is because, this time of the year, warmth and humidity will never stop battling to regain control…and that means we see a return of clouds, showers or rain each time the battle unfolds Right now, the next battle of air resulting in showers appears to begin Saturday evening or night and continue through Sunday, with at least and elevated chance of showers and thunder continuing into early next week.