Big changes coming to Northeast following midweek heat, storms

By Alex Sosnowski, AccuWeather senior meteorologist

A taste of autumn is in store for the northeastern United States by this weekend, but not before more heat and locally severe thunderstorms roll through some areas through the middle days of this week.

Fans and air conditioners will continue to get a workout into midweek.

While portions of central and northern New England got a break from typical August heat and humidity on Tuesday, conditions remained very much like summer farther south and west through the mid-Atlantic and central Appalachians.

The humid air and heat helped to fuel pop-up thunderstorms Tuesday afternoon through Tuesday evening. Washington, D.C. was hit by one of these storms, unloading flooding rain and hail over the nation's capital. 

The storms that roll into Ohio and Kentucky are part of a long-lived complex of thunderstorms that has had a history of high winds with downed trees and power lines.

AccuWeather meteorologists are tracking a push of much cooler and less humid air from Canada.

That push will spread across the Great Lakes region on Wednesday.

Ahead of the autumnlike air, gusty and severe thunderstorms are forecast over central and eastern New York state and Pennsylvania, and northern and western New England during Wednesday to Wednesday evening.

The Wednesday storms are likely to affect portions of the Interstate 80, 81 and 87 corridors and target the metro areas of New York City and Albany, New York; Montreal, Quebec and perhaps as far south as the Philadelphia area and as far east as Boston.

The cooler air will begin to sweep across the eastern Great Lakes, central Appalachians and western New England during Wednesday night.

From Thursday to the first part of Friday, a weak storm system is expected to move eastward along the press of cool air. The main effect will be to delay the cooldown and lowering humidity a bit over parts of the Ohio Valley to the Chesapeake and Delaware Bay regions as well as southeastern New England.

Showers are likely just north of the storm track, while heavy, gusty and severe thunderstorms can occur in the warm and humid air to the south.

However, from later Friday to Saturday, cooler and less humid conditions are likely to push farther to the south and east. Only portions of southern West Virginia and Virginia may stay unsettled and humid for a time.

The weather forecast to settle in late this week and this weekend will bring a reduction in energy demands and bring an improvement to air quality. People who have difficulty with hot and humid weather and are forced to limit time outdoors will be able to enjoy the weather and get some fresh air this weekend.

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However, people who are sensitive to cool weather or sudden drops in temperature may need to swap shorts and short sleeves with long sleeves and a jacket or sweatshirt.

As the cooler and less humid air takes root across the North and over the mountains, highs in the upper 70s to the upper 80s F will be replaced with highs in the upper 60s to the upper 70s this weekend. Nighttime lows are forecast to be in the 40s and 50s.

Meanwhile, over the mid-Atlantic and southern New England coast, highs in the middle 80s to the middle 90s will be replaced with highs in the middle 70s to the middle 80s. Nighttime lows will range from the upper 50s to the upper 60s.

At this level, temperatures are more typical for the middle of September and after the recent warmth and humidity, it may feel more like early October, factoring in a breeze at times.

The official arrival of fall is not until 3:50 a.m. EDT on Monday, Sept. 23.

Warmth is likely to bounce back for the last full week of August in the Northeast.

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