FIRST ALERT: Severe Thunderstorms, Tornado Touchdown Possible - NBC10 Boston

FIRST ALERT: Severe Thunderstorms, Tornado Touchdown Possible

Thursday's storms are expected to have the greatest impact on central and southern New England

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    Hot and Humid Wednesday With Scattered Afternoon Showers

    Wednesday: Hot and humid with scattered afternoon and evening strong storms. Highs around 90, heat index 95.

    Overnight Wednesday: Periodic showers and fog, rain south. Lows in the 70s, 60s north.

    Thursday: Cooler with showers and embedded downpours, some sun far north. Highs in the 70s.

    (Published Wednesday, July 17, 2019)

    Tropical air streaming north in association with the leftover moisture and energy associated with once-Hurricane Barry is now just a collection of variable clouds, erupting showers and thunderstorms and sultry air, but still will have enough of an impact on New England that we continue our First Alert on Wednesday.

    Showers and periodic rain in northern New England continue through the day, limiting any severe weather threat for northern areas but making for a wet day overall, while southern New England dips in and out of cloud cover but should get enough sun coupled with a southwest wind and tropical air to bump temperatures to near 90 degrees with humidity creating a "feels like" temperature in the lower to middle 90s.

    As a slowly approaching cold front interacts with the tropical air, thunderstorms will erupt in central and especially southern New England, and these thunderstorms will grow strong, with all producing torrential rain thanks to the humid air, and some growing strong enough to focus localized damaging wind gusts.

    In tropical air, the clouds develop near to the ground, which raises the possibility of a brief tornado touchdown. Though not likely, it’s also not impossible, so our team will be fixated on the radar, including our exclusive Storm Ranger mobile Doppler radar that we’ll deploy to central Massachusetts Wednesday afternoon and evening.

    Wednesday night, the rain slowly settles south over far southern New England as thunder diminishes, and Thursday we’ll see areas of showers and embedded downpours cropping up over the southern half of New England, while northern New England stays dry.

    The most noteworthy weather feature Thursday may be the new air: much cooler with highs only in the 70s and noticeably less humid near and north of the Massachusetts Turnpike. Heat is poised to return from west to east Friday, and while there’s some uncertainty about just how hot Friday afternoon becomes, Saturday’s heat will be dangerous, with actual highs nearing 100 degrees and heat index or "feels like" temperatures around 105.

    This poses a risk for those with no cooling options at home and encourages cooling centers and splash pads to open across the region, especially considering Saturday night low temperatures will likely be either side of 80 degrees, meaning little rest for the body for folks without air conditioning before temperatures climb back into the 90s Sunday.

    The heat should break sometime Monday with thunderstorms, some of which may crop up again Tuesday before new air arrives for the middle of next week in our exclusive First Alert 10-day forecast.

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