Summer heat and approaching cold front to fuel multi-day severe storm threat in the Northeast

As near-record heat builds across much of the East Coast alongside a humid air mass, weak disturbances will move through the region on Wednesday and Thursday.

This will help ignite scattered severe storms across the Northeast and Mid-Atlantic during the afternoon hours, all ahead of a greater risk for severe weather on Friday.

Starting on Wednesday, a weak dip in the jet stream will migrate across the region and move into an area with increasing stability.

WHAT IS THE JET STREAM?

During the peak heating hours of the day, with dew points climbing into the upper 60s, isolated storms capable of producing damaging wind gusts are possible across New York, Pennsylvania and New Jersey, as well as southward into the Delmarva region.

On Wednesday and Thursday, a Level 1 out of 5 severe storm risk is in effect from Richmond, Virginia, through Pittsburgh, Pennsylvania, and into Upstate New York.

Friday brings the highest risk for severe storms and includes portions of Kentucky through Upstate New York. A Level 2 out of 5 severe storm risk includes more than 50 million Americans.

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As southerly winds continue to pump record heat and high humidity into the region Friday afternoon, an approaching cold front will act as the focus for storm development, according to the FOX Forecast Center.

Storms are expected to develop across the lower Great Lakes and the upper Ohio Valley by early afternoon, with activity advancing east toward the Hudson Valley and southeast into the Mid-Atlantic through the evening.

The primary threats with these storms as they move east will be damaging winds and large hail, although a few tornadoes can't be ruled out.

By the end of the week, millions are expected to experience some of the warmest temperatures of the year across the East Coast.

HOW HIGH PRESSURE AND LOW PRESSURE DRIVE THE WEATHER

A powerful area of low pressure moves across central and southern Canada on Thursday and Friday, with high pressure positioned just off the East Coast.

Because of this, strong southerly winds will help draw heat and humidity all the way into New England.

DEW POINT VS. HUMIDITY: WHICH ONE IS A BETTER MEASURE OF HOW MUGGY THE AIR FEELS?

Starting Thursday, a very moist airmass will start to move into the Carolinas, Mid-Atlantic and Northeast, where dew points will climb into the upper 60s and low 70s. 

With high moisture in place and high temperatures surging to around 10 to 15 degrees above average, heat index values will be well into the mid 90s and low 100s.

Into Thursday and Friday afternoon, highs will reach the mid to upper 90s for many locations from Raleigh, North Carolina, through Washington, D.C., and up into New York City.

There are currently Heat Advisories in place for the New York City area. Many record-high temperatures are also possible later this week.

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Through Friday, more than 40 record highs could fall, including in cities such as Washington, D.C. and Philadelphia. These cities could also experience their hottest temperatures so far this year.

Stay with FOX Weather for the latest information about severe storms in the Northeast.