Cooler today, then seasonably pleasant the rest of this week

Synopsis:

 

After the FROPA on Saturday, the 540-mb. height lines dove down towards PA yesterday and today. This translates into cooler weather for one more day, before we see a ridge of high pressure moving towards PA and bringing more seasonably pleasant temperatures with it. However, by Wednesday, we will see a cold front advancing towards the state, merging with a frontal boundary coming up from the Ohio River Valley. This will bring showers across PA, and possibly a few isolated thunderstorms as well. By Wednesday night, the cold front clears out, but the stalled frontal boundary stays behind. It will slide to the north again (the stalled frontal boundary, that is) by Friday and into the weekend, bringing scattered showers. Temperatures after today will stay seasonably pleasant, even after Wednesday's cold front passes through.

 

Short-term:

 

Still running cool today due to lowered 540-mb. height lines across PA. Leftover moisture in the upper levels will continue to give clouds to the western and central portions of PA (think widespread pancake cumulus), and temperatures will run a good 5-10 degrees below where they should be this time of year. However, by tomorrow, a decent-sized area of high pressure will move from the south and west over PA, which will provide a beautiful day for tomorrow. It will be short-lived, though, as clouds are once again on the increase for Wednesday's two systems that will clash just to the south of PA ...

 

Long-term:

 

A cold front is currently making its' way through central Canada, and will move south and east over the Great Lakes towards PA. It should pick up a decent amount of moisture moving over the Great Lakes - hence, a good chance of showers (and possibly a few isolated thunderstorms as well). Another system (a frontal boundary) is moving from the South towards the NE, and the two frontal systems are expected to merge by some point Wednesday. Once the cold front pushes through, this frontal boundary will move south for Thursday. However, by Friday, it looks to slide north again, and it will be a question of how much moisture is associated with it for Friday and into the weekend, and what areas of PA see showers. With the cold front passage on Wednesday, there really isn't any very cool air behind it, so temperatures will only fall a few degrees Thursday and into the weekend. Not too bad of a way to start the first full week of fall!