Cool, dry air to follow stormy stretch in northeastern US

It was a stormy start to the week across the Northeast but forecasters say that changes are on the way that will bring cooler, drier and less humid air into the region.

The first part of June has started off warm across the region, with temperatures generally averaging 4-8 degrees Fahrenheit above normal. The warm weather has also been accompanied by a surge in humidity levels since last week, adding to the sticky and summery feel to the air.

On this image, captured on Monday afternoon, June 14, 2021, bubbly clouds associated with thunderstorms can be seen over the interior Northeast. Swirling clouds off the North Carolina coast were associated with Tropical Depression Two, which has since strengthened to Tropical Storm Bill. (CIRA at Colorado State/GOES-East)

Around the middle of June, average high temperatures range from the lower to middle 70s in New England, to the lower to middle 80s in the mid-Atlantic.

High temperatures were near to slightly above these seasonable marks to end the weekend, with humidity levels remaining high. This warm and humid environment provided a conducive environment for heavy to locally severe thunderstorms to develop as a storm system dropped southward.

Quarter-sized hail was spotted in Pennsylvania and Ohio on Sunday. In Allegheny County, Pennsylvania, hail fell for five minutes straight. Trees were downed in West Virginia, Maryland, Virginia, Ohio and Pennsylvania, some blocking roads and highways and downing power lines as they fell.

In Masontown, Pennsylvania, an entire mobile home park was submerged in water after thunderstorms led to flooding. According to a local reporter, eight people had to be evacuated but no injuries were reported.

These storms failed to whisk out the sticky air across the Northeast, and showers and thunderstorms once again erupted on Monday.

Similar to Sunday, these storms once again brought hail, damaging wind gusts along with flooding downpours. High wind reports were clustered around southeastern Ohio, the northern border of West Virginia and southwestern Pennsylvania along with a line of reports in central Pennsylvania. By Monday evening, over 25,000 customers were without power across Pennsylvania and New Jersey. The severe storms reached the Philadelphia, Baltimore and Washington, D.C., metro areas with damaging wind gusts and flooding downpours on Monday night.

The last of a series of disturbances to swing through the Northeast will bring showers and stray thunderstorms on Tuesday. Compared to the past few days, widespread severe weather is not anticipated, but any thunderstorm could cause brief downpours and gusty winds, along with dangerous lightning.

This last disturbance and an associated southward dip in the jet stream will protect the Northeast from an assault by Tropical Storm Bill, located off the coast of North Carolina and Virginia on Monday night. Winds from the jet stream dip are forecast to keep the tropical system well offshore of the U.S.

Forecasters say it will take until the middle of the week for drier air to completely overtake the region and diminish rain chances.

"By midweek, an area of high pressure will develop over the Great Lakes and pull drier air across much of the Northeast. Not only will this drier air help to suppress rain chances, it will also significantly lower humidity levels," AccuWeather Meteorologist Mary Gilbert said.

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The lower humidity will make it more comfortable for residents to exercise or partake in other strenuous activity outdoors.

Air conditioners and fans are also likely to be given a rest, replaced with fresh air from open windows.

"Many locations from Burlington, Vermont, to Washington, D.C., will experience high temperatures 4-8 degrees below average for the middle of June by midweek," Gilbert said.

Underneath mainly sunny skies on Wednesday and Thursday, high temperatures are expected to be generally in the 70s with some 60s across the northern tier.

The nighttime hours will be when the cooldown is likely to be most noticeable. Across the interior, lows in the 40s and 50s may require some residents with plans in the evening or early morning hours to break out a light jacket or long sleeves.

Warmer and more humid conditions are likely to quickly return for the end of the week as the next storm system approaches.

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