The tropical steam bath engulfing the Berkshires and the rest of the Northeast is expected to trigger thunderstorms, some of them potentially severe, until a cooldown Thursday.

The heat dome tightened its grip on the region Monday, with a high of 88 at Pittsfield Municipal Airport, though that was short of the record for the date, 92 in 1999.

High humidity, combined with pollen-laden mists drifting over parts of the county, continue to make outdoor events, work and play unpleasant, at best.

On Tuesday, the National Weather Service in Albany, N.Y., predicted that scattered to numerous afternoon showers and thunderstorms could dump heavy rain, especially if the storms move slowly or stall over the region. Isolated flash flooding is possible, especially in low-lying, poor-drainage and urban areas.

The likeliest prospects for foul weather are from 2 to 8 p.m. Tuesday, especially for areas along and south of the Massachusetts Turnpike, according to meteorologist Christina Speciale.

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“Heavy rainfall from storms could impact the afternoon commute, so, motorists are encouraged to drive cautiously and allow for extra travel time,” she stated.

More showers and thunderstorms Wednesday afternoon could prolong the risk of heavy rain and possible flash flooding in some areas, with more high humidity.

Both days will be unseasonably hot, with highs well up in the 80s. That is about 15 degrees above the average early June high of 73 in Berkshire County.

The leading edge of cooler air will arrive by Wednesday evening, in time for a refreshing four-day period Thursday through Sunday, mostly dry and with only a 30 percent possibility of scattered showers Friday. That’s good news for graduations and outdoor activities over the weekend.