Relief from eastern US heat wave is on the way

An end of the heat is in sight for all of the Midwest and Northeast and much of the Southeast before the week comes to an end.

Major relief is on the way for the summer swelter that sent temperatures and humidity levels soaring, air conditioners working overtime, and people flocking to beaches and pools in the Midwest and the East. However, AccuWeather meteorologists say that while the humidity will come down in the North, it is likely to stick around in the Southeast.

Some of the worst days of the current heat wave will be Monday and Tuesday in much of the East. In some cases, the highest temperatures of the summer so far will be combined with high humidity. Temperatures Tuesday are forecast to reach 104 F in Washington, D.C., and Baltimore; 98 in Philadelphia; and 97 in New York City.

Even where temperatures don't quite reach the season-high mark, the combination of temperature, humidity, intense sunshine and light winds will push AccuWeather RealFeel® Temperatures well over 100, perhaps eclipsing 110 for a few hours in some locations.

Meanwhile, a cold front is gathering momentum over the Upper Midwest at the start of the week. The jet stream will give it an extra boost to move it along in the short term.

"The air coming in will be nothing short of refreshing compared to conditions in recent days and lingering for the first half of the week in the Northeast," AccuWeather Senior Meteorologist Dave Dombek said.

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In many cases, daytime highs will be slashed by 15-20 degrees Fahrenheit from the start of the week to Wednesday in the Midwest and Thursday in the Northeast. Highs ranging from the upper 80s to near 100 will be replaced with highs ranging from near 70 to the mid-80s. By the middle to late part of the week, nighttime lows will be well down into the 50s over much of the Midwest and the mountains of the Northeast.

The effect of the lower temperatures will be magnified by much less humid air. For millions in the Midwest and interior Northeast, this will be an extended period of comfortable conditions at a time of the year that is typically quite hot and humid.

Highs in the 90s to start the week will be swapped with highs in the 70s from Wednesday to Friday in Chicago. In Washington, D.C., highs in the low 100s will be replaced with highs in the middle to upper 80s from Thursday to the weekend. In the northern tier of the Midwest and Northeast, as well as the central Appalachians, going from routine highs near 90 to nighttime lows in the 50s may feel jarring for some.

Some of the biggest drops in daytime temperatures will be experienced over the interior Southeast, where highs near 100 into Wednesday will be swapped with highs in the lower 80s, in locations such as Greenville, South Carolina; Atlanta; Charlotte and Raleigh, North Carolina.

"The sweep of less humid air will be fairly swift from the Midwest to the interior Northeast," Dombek said, "But the front's forward speed will begin to slow along the New England and mid-Atlantic coasts.

As a result, showers and thunderstorms associated with the front may take the better part of Thursday to depart the coastal Northeast, and the big drop in humidity levels is not likely to occur along the Interstate 95 corridor of the region until Thursday evening or Friday morning.

The front is forecast to stall over the Southeast. The cooler air will be accompanied by multiple days of extensive clouds, showers and thunderstorms that can help ease drought problems from the latter part of the week into the weekend. However, humidity levels will remain high over much of the Southeast.

Showers and thunderstorms, with the likelihood of severe weather, will crescendo until the front moves through the Ohio Valley and eastern Great Lakes Tuesday and then much of the balance of the Northeast Wednesday. Showers and storms will congregate in the Southeast Thursday and Friday.

Any non-flooding downpours will be welcomed, as drought conditions have escalated quickly in recent weeks due to intense sunshine and missed opportunities for rain.

Once the cooler and less humid air settles into the Northeast, it is forecast to stick around through the weekend and perhaps into the start of next week. Humidity levels will creep back up over the Midwest starting this weekend, while warmth builds over the Southeast as high humidity levels linger.

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