Downpours, humidity to precede late-week cooling trend in East

Spotty showers will ramp up to downpours and thunderstorms by midweek before cooler air settles in and reverses the warming trend with higher humidity later this week in much of the East.

Back-to-back storms will swing through the Midwest and Northeast this week, the second of which will bring more downpours and disruptions starting at midweek. AccuWeather meteorologists say another shift in the weather pattern is in the offing in the wake of the second storm.

The first storm through Tuesday night will still produce clouds, spotty showers and thunderstorm activity—perhaps enough to disrupt some outdoor plans and projects in the central and southern Appalachians and Piedmont and the mid-Atlantic.

The second storm will be a bigger rainfall producer than the previous system for the central Appalachians, mid-Atlantic and parts of the Southeast. It's much more likely to produce downpours intense enough to lead to street and highway flooding in some cases from Wednesday to Thursday.

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The drenching downpours may hold off in New York City until late Wednesday night and may not reach Boston until Thursday. However, locations such as Philadelphia may be in the downpour zone by Wednesday evening, and people in Washington, D.C., may be dodging rain episodes at any time on Wednesday. Atlanta may be subject to spotty thunderstorm activity into Tuesday afternoon, then more general showers and thunderstorms are in store from Tuesday night to Wednesday.

Dry air in New England will initially resist showers. Still, even in this region, moisture will eventually prevail, and showers with spotty thunderstorms will prevail later this week.

Showers and thunderstorms may struggle to occur in much of the southeastern corner of the U.S., including the Florida Peninsula, most days this week.

Severe weather to shift eastward on Wednesday

The system moving eastward at midweek will likely be strong enough to set off locally severe thunderstorms with gusty winds from the eastern Great Lakes to the Ohio and Tennessee valleys and perhaps some of the western slopes of the Appalachians.

New pattern to emerge before the weekend

Following midweek downpours from the Appalachians and Piedmont areas to the mid-Atlantic and southern and western New England, a batch of unusually cool air will pivot southeastward across the Great Lakes to much of the Northeast later this week and this weekend.

The air coming in will produce temperature departures of 5-15 degrees below the historical average for early June. It will replace highs in the 70s to near 80 in the mountains and the 80s to near 90 in coastal areas, with highs mainly in the 60s to low 70s in the mountains and the 70s to near 80 in coastal areas.

Billowing clouds, showers and spotty thunderstorms are expected to accompany the cooldown. Most of the shower activity will be from the midday hours to the early evening, as the sun will drive them.

In some cases, the more robust showers can evolve into thundershowers with small hail and gusty winds.

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