The current weather pattern in place features a large ridge of high pressure which actually came off the Atlantic, moved west and has now established itself over the Ohio Vally, this upper level ridge is leading to a large dome of heat over the Central and eastern US
Currently as of 1030 AM most areas sit in the low to mid 90s with heat indices approaching the lower 100s , today and tomorrow is when the heat wave will peak with most areas hitting the mid to upper 90s , some lower 100s possible with heat indices ranging from 105-115 degrees , overall very dangerous conditions to stay outdoors in and the other big problem is low temperatures at night only in the mid 70s to around 80 there isn’t much relief at night especially with the humidity mixed in making heat indices in the mid 80s to low 90s lasting through much of the night, although I can’t rule out some isolated activity especially tomorrow afternoon as the high pressure begins to loosen its grip a bit, which could bring brief relief to very isolated areas, as the ridge moves southeast and we have an approaching cold front humidity will gradually rise over the next 48-72 hours as winds turn south-southwest
Relief is on the way though in the form of a strong cold front wich will drop south and east of of Canada . The front will begin to approach Saturday morning, and between all the heat/humidity over the area and the cooler drier Canadian air mass that will be moving in, plus a strong cold front will lead to moderate to high instability and thus a good chance of severe thunderstorms , especially Saturday afternoon/evening with the frontal passage although showers and storms will be possible at any time on Saturday , still on Saturday highs will be in the low to mid 90s for most areas besides high elevations where mid to upper 80s can be expected , and with incredibly high humidity levels expected it will feel much worse.
The SPC as put the whole area n a slight risk for severe weather at this time, I think there is potential for this to go higher over time in the next 2 days , highest threat with these storms will be flash flooding with very heavy downpours and damaging wind gusts in excess of 50 mph
Sunday will continue to be quite warm as the cool air mass stays a bit delayed but we will see humidity gradually fall through the day and winds gradually turn NW highs in the mid 80s to low 90s can be expected before the cooler air mas makes it here, with low to mid 80s expected through much if not all of next week with generally dry conditions and low humidity, lows in the upper 50s NE PA to mid 60s along the coast are expected so overall a very comfortable period of weather is expected.