The weather pattern has taken a pretty quick turn over the past 48 hours, from a nice trough and comfortable conditions to now a strong ridge, a southwest flow and oppressive heat/humidity over the forecast area with current temperatures in the upper 80s to mid 90s area wide and heat indices ranging from the mid 90s to lower 100s ! It does appear some locations will tie or break the record high for today but just as quickly as the heat came in, it will come to and end
We see on the 500 mb map our next trough is dropping south and east out of Canada , and with it is a pretty strong cold front that will slowly pass through the area tomorrow night into early Friday . Thursday will continue to be very warm and humid, although not quite as warm as today as an increase in cloud cover is expected and as the cold front comes closer the temperatures aloft will cool just a tad, it will still be oppressive though with widespread mid to upper 80s (perhaps an isolated 90 degree reading) with dew points in the lower to mid 70s and heat indices in the mid to upper 90s , and lower 80s in the higher elevations with heat indices in the upper 80s to around 90, lows tonight will only fall into the lower to mid 70s for most of the forecast area with some urban locations perhaps being trapped In the upper 70s to around 80 for LOW temperatures along with very high humidity and similar temperatures for tomorrow night are expected
I also can’t rule out an isolated to widely scattered storms late this afternoon and evening for NE PA through Central PA as a shortwave disturbance moves through Central /West PA later today, some of which can be strong to severe, highest threat being very heavy rain and gusty winds, most of the activity should remain west of the forecast area though.
Starting tomorrow afternoon we will see the cold front begin to move in, so storm chances will pick up again for NE-Central PA later in the afternoon, there is the chance for a bit more widespread severe weather over these locations , then the front will march towards coastal locations later tomorrow night and early Friday morning, I don’t expect this to be a big deal for a majority of the forecast area as the best dynamics will be to the north and the timing wont be so good for severe weather either , but still scattered storms are expected, highest threat again is very heavy rain and slow-moving storms. Areas like Connecticut, especially NW portions could also see the stronger to severe activity as you will be closer to the best dynamics .
The front will clear the coast early on Friday and a MUCH cooler and drier air mass will take hold through much of next week , Friday will be in the 70s for most of the area with widespread 40s to low 50s for lows Friday night-early Saturday and Saturday and Sunday most of the area will struggle in the mid to upper 60s, low 60s NE PA-NW CT and low 70s in urban locations , lows will be widespread in the 40s with perhaps some 30s possible for the coldest interior locations . as we head into early next week we will see a reinforcing shot of polar air which will keep these temps around through mid-late week.