Northeastern US: Building heat into midweek to precede downpours fueled by Barry

By Kristina Pydynowski, AccuWeather senior meteorologist

AccuWeather RealFeel® Temperatures will be on the rise across the northeastern United States through the first half of this week before moisture from Barry arrives and triggers downpours.

While Monday will feel like a typical summer day in the Northeast, temperatures and humidity levels will climb for Tuesday and Wednesday.

High pressure sliding eastward will open the door for the steamier conditions to arrive, according to AccuWeather Meteorologist Randy Adkins.

"A moist, southwesterly flow of air setting up behind the departing high will help usher in a more humid air mass for the midweek period with temperatures at or above average for most," he said.

Widespread highs in the lower 90s will expand northward along the Interstate-95 corridor from Washington, D.C., to Philadelphia on Tuesday.

A few locations farther north will crack the 90-degree mark on Tuesday before highs in the 90s engulf nearly the entire I-95 corridor on Wednesday.

Similar highs will bake Allentown and Harrisburg, Pennsylvania, and Charlottesville, Virginia, at midweek.

When humidity is factored in, AccuWeather RealFeel® Temperatures will soar between 95 and 105 these days.

Residents will want to be sure to drink plenty of water, wear light clothing and take frequent breaks if strenuous activities cannot be avoided during the midday and afternoon hours to avoid suffering from heat-related illnesses.

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Taking a dip in your community's local swimming pool or heading to the beach is another great way to beat the heat, but be wary of thunderstorms that will erupt.

Barry, as a tropical rainstorm, will spread drenching showers and thunderstorms across the Ohio Valley and into the interior Northeast on Wednesday.

East of the Appalachian Mountains, spotty thunderstorms will ignite in the afternoon with more numerous showers and thunderstorms to follow at night and into Thursday as Barry's moisture surges eastward.

"Given how much moisture will be in place, there is the potential for heavy rainfall with any showers or thunderstorms that do develop," according to Adkins.

"Fortunately, downpours should be moving along rather briskly, so the threat for widespread flash flooding is low," he added.

A few issues can develop in low-lying and urban areas. Travelers, meanwhile, may encounter minor delays.

"Non-flooding downpours may not be a bad thing in areas where lawns are turning brown and gardens and crops are being stressed by hot weather and dry soil conditions that occasionally develop in July," according to AccuWeather Senior Meteorologist Alex Sosnowski.

While actual temperatures will be trimmed slightly as the downpours swing through, residents will not be treated to a reduction in the sweltering humidity. That will be the case even after the wet weather departs.

Instead, the door will swing wide open for more heat and high AccuWeather RealFeel® Temperatures to engulf the Northeast to end the week.

AccuWeather meteorologists will be closely monitoring the threat for clusters of severe thunderstorms to erupt along the rim of this heat in the Upper Midwest and dive into a part of the Northeast.

Download the free AccuWeather app for more details on temperature trends in your community. Keep checking back for updates on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.