Storms bring thunder, flash flooding risk to northern New England

Storms are moved New England Tuesday, with weather alerts in effect across the northern part of the region for much of the evening.

Flash flood warnings and severe thunderstorm warnings were in effect in parts of Maine, New Hampshire and Vermont. They have since expired.

See all severe weather alerts in your area here, and interactive weather radar below.

Although widespread flash flooding isn’t expected Tuesday, the sheer amount of rain in recent days has left the ground of New England – especially central, western and northern New England – unable to absorb much additional rain, so with downpours and thunder expected for some, it won’t take much for localized flash flooding to result. 

Tuesday starts quiet with only a few showers in northwest New England and a separate disturbance over the Atlantic set to scrape across Nantucket and perhaps the Outer Cape with a few showers from mid-morning to mid-afternoon.

By Tuesday afternoon, however, an approaching cold front and associated jet stream disturbance aloft will move into New England from northwest to southeast, triggering showers and thunderstorms, with the highest chance northwest of a line from Boston to Providence. 

Afternoon scattered showers and thunder will tend to converge by late day and evening over the deep interior, posing an elevated risk of flash flooding for Vermont into central New Hampshire, and perhaps in a few spots of central to western Massachusetts and western Connecticut if downpours sit long enough over these areas. 

That said, significant breaks of sun outside of any showers and downpours will boost temperatures into the 80s again Tuesday, with humidity creating a heat index value around 90 degrees at the warmest time of day. 

Any scattered showers and thunder fizzles early Tuesday night, leaving areas of fog behind with lows in the 60s, but Wednesday should bring a slight yet noticeable drop in humidity for most areas near and north of the Massachusetts Turnpike. Although this drop in humidity will reduce storm chance, it doesn’t eliminate the chance entirely, and areas south of the Pike will still have plenty of humidity, meaning renewed scattered storms will likely develop in the afternoon for these areas, in particular. 

A similar scenario of isolated to widely scattered storms is the expectation of our First Alert Team on Thursday, but returning deep atmospheric moisture Thursday night into Friday will elevate the chance of more numerous and widespread showers and thunderstorms. 

The passage of a cold front late Friday or Friday night will lower the number of showers and storms Saturday, though scattered afternoon thunder is still a distinct possibility. Then Sunday and Monday continue to look at least a bit less humid with a lower chance of storms for many. 

Heat rebuilds, along with humidity for the middle to end of next week, with temperatures nearing 90 by the end of next week.