Much of the northeastern United States avoided rounds of severe weather during the first part of this week, but luck may be running out for at least part of the region into Thursday night, AccuWeather meteorologists caution.

A wedge of cooler air centered over the North Atlantic and New England remained in place into Wednesday. This has forced complexes of storms to dive southward toward the Carolinas and Georgia this week after hammering the Great Lakes region, where they left hundreds of thousands without power amid sweltering heat.

A shift in the jet stream will help steer potent storms from the Midwest back toward the Northeast Thursday and Friday, forecasters say. Parts of the mid-Atlantic region got a sample of the pattern change late Wednesday night and Thursday morning as thunderstorms that erupted over the central Appalachians expanded toward the coast.

Severe thunderstorms will fire along and ahead of cooler and less humid air that will mark an end to highs in the 90s and low 100s in the Midwest. However, as more refreshing air arrives in the Midwest, the opposite will unfold in the Northeast.

The Northeast will experience a brief surge of that heat and high humidity from Thursday to Friday as weather systems begin to move along from west to east, according to AccuWeather Senior Meteorologist Dean DeVore.

"Temperatures in many areas will surge well into the 80s to lower 90s F," DeVore said.

GET THE FREE ACCUWEATHER APP

Have the app? Unlock AccuWeather Alerts™ with Premium+

The building heat will help give the storms that erupt a boost, experts say.

The main threat of severe weather will unfold into Thursday evening. Storms will first target portions of Ohio and the Canadian province of Ontario before expanding in coverage and strength in western portions of Pennsylvania and New York and northern West Virginia.

From there the storms will roll eastward, most likely at peak intensity across central and northern New York, central and eastern Pennsylvania and northern portions of Maryland and Virginia Thursday evening.

People in these areas should be prepared for rapidly changing weather conditions where fast-moving and strengthening storms can bring frequent lightning strikes, damaging winds, large hail and flash flooding, AccuWeather meteorologists say.

There is even the potential for a tornado to be spawned in a few of the strongest storms.

Major metro areas at risk for potentially damaging storms into Thursday evening include Pittsburgh, Harrisburg and Scranton, Pennsylvania, as well as Rochester and Binghamton, New York.

There is the risk that the storms may still pack a punch as they reach the cities of Washington, D.C., Baltimore and Philadelphia before weakening after dark Thursday farther to the east.

New York City will have thunderstorms track through the area Thursday night, but the storms will likely be past their peak intensity. Still, locally gusty winds and torrential downpours can cause problems on the roads, delays at the airports and difficult conditions for pedestrians.

On Friday, the cool front will press on toward the mid-Atlantic and New England coasts. There may be enough daytime heating ahead of the front to trigger locally heavy, gusty thunderstorms near and east of the Interstate 95 corridor, such as the beaches, in southeastern Virginia and in the Boston area.

In the wake of the front, temperatures will be slashed by an average of 10-20 degrees. "This means widespread highs in the 70s to low 80s are in store with nighttime lows ranging from the upper 40s and 50s in the mountains to the upper 50s and lower 60s in the major I-95 metro areas this weekend," DeVore said.

Temperatures in most areas of the Northeast this weekend will be 5-10 degrees below average for the middle of June, and most summertime outdoor activities can still be enjoyed this weekend thanks to abundant sunshine.

As the Northeast once again basks in temperatures more typical of May this weekend, heat will once again surge northward across the Plains and Mississippi Valley.