By Matt Peterson

PHILADELPHIA (CBS) — As the first round of showers and storms clear off, the Delaware Valley will be sitting in a hot and very humid air mass once again. This means the region will get a new round of dangerous conditions to deal with Sunday afternoon.

Overall, it should be a partly cloudy afternoon. Highs today will soar into the lower 90s and when you add in the high humidity it could feel as hot as 100 to 105 degrees at times, especially across the I-95 urban corridor.

A heat advisory is in place for Philadelphia this afternoon. Due to the high heat and humidity, there is a chance for a couple of pop-up afternoon showers or thunderstorms mainly after about 5 p.m. as a weak surface cold front passes over the area.

If thunderstorms were to develop they could quickly become severe, with strong winds, heavy rain, and even an isolated tornado is possible.

There is a slight risk of severe weather across the Lehigh Valley and Poconos today. Storm chances will wain thrown the night but will still be possible.

Lows tonight should stay in the mid-70s.

The coming workweek is going to be fairly active for the first few days.

Monday clouds are expected to increase in the afternoon during what should be a pretty dry day across the region.

There is a slim chance for a couple showers or thunderstorms late in the day Monday, but the better chance for a passing storm will come overnight into Tuesday.

At this time the area could start to tap into some tropical moisture from Extra-Tropical Cyclone Isaias.

This means rain on Monday night could be heavy at times.

The main impact of Isaias is expected to come on Tuesday. This is when the remnants of the system will pass directly over the region.

We will likely be dealing with heavy rain and gusty winds all day.

The exact details on the timing and extent of the worst of impacts from Isaias are still being determined but we should be vigilant throughout Tuesday for dangerous weather.

By Tuesday night, Isaias should be making its exit to the north.

A surface front will be trailing behind the departing system, so a few lingering showers or a pop-up thunderstorm cannot be completely ruled out on Wednesday.

But, overall it looks like a day of just decreasing cloud cover and seasonable highs in the 80s.

Thursday high pressure will build into the area, leaving a mostly sunny day, seasonable highs and lower humidity.

A few more thunderstorms are possible Friday, with chances for 90s to return for the weekend.