Sunday dawns with pockets of clouds and fog that will burn off for a humid blend of sun and clouds, though an approaching disturbance Sunday afternoon and evening raises the chance of scattered showers and thunderstorms in Western New England - particularly Western Massachusetts through Connecticut.
The combination of high temperatures in the 80s, dew point temperatures in the 70s and a changing wind with height will favor some storms becoming strong in these western communities, and while they will weaken as they drift east, a Sunday evening storm can’t be ruled out in Rhode Island and on Cape Cod.
These scattered storms represent another, reinforcing push of hot and humid air that will be firmly in place Monday with high temperatures surpassing 90 degrees and heat index values in the lower to middle 90s, though the absence of any strong disturbance limits the chance of thunder.
Meanwhile, to our south, Isaias is forecast to draw north up the Eastern Seaboard - the exact storm track is to be determined, but a landfall in the Carolinas with a north-northeast motion up the coast is quite likely.
If the storm stays inland as it moves north, it will weaken steadily and deliver only a round of gusty downpours to most of New England Tuesday or Tuesday night - if Isaias stays over water and parallels the East Coast, it will maintain more strength and be a more dangerous storm for New England.
Although the strength of a large high pressure dome over the Western Atlantic favors a more inland track, there’s plenty of time and therefore plenty of uncertainty on how the storm will unfold.
Regardless, it should be exiting Wednesday, probably early, and more comfortable air arrives for the end of the week with temperatures in the 80s through the rest of the exclusive First Alert 10-day forecast.