New England sits on the cusp of significantly more humid air to our southwest, but remains in comfort for one more day. Nonetheless, being on the battle zone of two different air masses means variable clouds through the day with the most significant periods of sunshine during the afternoon to early evening.
Aloft, there’s enough dry air to preclude thunderstorm development in New England Tuesday afternoon, but as humidity streams in both at ground level and aloft, not only will the second half of Tuesday night turn less comfortable for those sleeping without air conditioning, but a few showers will crop up by dawn Wednesday.
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The air setting up shop in New England will be the most humid of the season thus far, and certainly sets up the most intense stretch of humidity, with dew point temperatures – the measure of the amount of moisture in the air – approaching or exceeding the oppressive 70 degree mark Wednesday into the weekend. Not only will the humidity make for a steam bath feeling Wednesday onward, but the increased moisture in the atmosphere will serve as fuel for scattered showers Wednesday morning, scattered showers and downpours during the afternoon and scattered strong thunderstorms, prompting the issuance of an NBC10 Boston/NECN First Alert Wednesday late day and evening.
With so much moisture in the air, rainfall rates will be exceptional in any storms, meaning ponding of water is likely under these storms. Strong wind gusts may cause localized damage, cloud-to-ground lightning will pose a threat and some hail is possible in stronger storms.
Isolated thunderstorms are possible Thursday afternoon or evening in exceptional heat and humidity but aren’t expected to be widespread – the bigger story will be high temperatures near 90 degrees with high humidity pushing the heat index into the 90s.
More tropical humidity is expected Friday, but attention will turn to an organizing storm center off the Mid-Atlantic coast that will be fueled by tropical moisture and is being watched closely not only by our First Alert Weather Team but also by the National Hurricane Center for possible development of a Tropical Depression or Tropical Storm.
Regardless of how organized the storm becomes, it represents a shot of tropically infused rain and gusty wind – so we’ve hoisted a First Alert for late Friday into early Saturday, though the impact of the system – from track to intensity - will depend entirely on how organized it becomes in the second half of this week, and will be one major focus of our Weather Team.
Lingering humidity and scattered storms are probable Sunday, with a bit less intense warmth and humidity expected toward the middle of next week with hints of another burst of warmth and humidity for the close of next week at the end of our exclusive First Alert 10-day forecast.