Over the course of the last few weeks, bouts of summer warmth have mostly failed to yield thunderstorms during the afternoon. Though a typical staple of a summer pattern, humidity to drive the storms has been largely absent, owing to repeated incursions of dry, Canadian air that affords daytime warmth with strong summer sun, but keeps the atmosphere unfavorable for deep, vertical cloud growth for thunderstorms, seen in hot and humid air masses.
There are indications this storm-free pattern will change somewhat this week, giving hope to a soaking rain for some New England communities, but also raising the prospect for some locally damaging storms to develop. Of course, for those with outdoor plans, the rhyming rule returns: "When thunder roars, go indoors" – if you are close enough to hear the thunder, then lightning is a concern.
As for the timing of thunderstorms in the coming days, most will focus on the passing of upper level atmospheric disturbances – traversing New England Monday overnight, Tuesday afternoon, Tuesday night and Wednesday afternoon.
After some light showers in far Northern and Western New England Monday afternoon, Monday night's showers develop over interior Southern and Central New England, and may contain a few downpours or rumbles of thunder, leaving some pockets of showers and rain for the Tuesday morning commute.
As Tuesday progresses, showers will tend to contract toward a slow-moving cold front entering Northern and Western New England, but also will become more intense, with some storms possibly becoming severe with locally damaging wind gusts in Vermont Tuesday afternoon or Western Massachusetts Tuesday evening.
Though it’s been dry lately, if storms follow the same path long enough, a few spots in Vermont could actually see some flash flooding, though that possibility is a bit more tenuous.
Some of these late Tuesday storms will meander through New England into the overnight, then a renewed disturbance Wednesday will couple with the very slow moving cold front, still draped across New England, to produce more widespread thunder, focused especially during the afternoon when some storms may reach severe limits due to locally damaging wind gusts again.
By Thursday, drier air will return to New England, though Friday and Saturday bring a renewed chance of scattered afternoon thunder – mostly over interior New England – before fantastic weather is likely to return for the July 4th holiday.