Our weather pattern is going to take a transition to a more volatile state over the next week in the wake of the southern storm system that couldn't get north and bring us snow over President's Day weekend. Temperatures will moderate after a chilled start on Monday, with highs likely near 50 degrees as quickly as Tuesday. A weak disturbance will cross the region on Tuesday night, bringing some showers and sprinkles as it moves through. It'll be rather uneventful as it moves through and most spots will not get much more than a sprinkle or short round of showers.
The volatile, stormy look in the pattern will take hold later on this week with a storm system that will organize across the Midwest and lift into the Great Lakes. The lingering front from Tuesday's disturbance will hang across the region, separating building and significant warmth across the South from mild weather across the Northeast.
This front will have a couple of disturbances that meander along it, meaning that we could see some showers on Thursday morning and again Thursday night into Friday morning. The second of these disturbances may help push the front north of the region altogether as a warm front. Assuming this does indeed take place, temperatures on Friday could reach or breach 60 degrees throughout Eastern Pennsylvania as the Great Lakes low intensifies and blasts a cold front through the region late in the day.
Breezy, mild conditions on Friday could also include periods of rain and perhaps even thunderstorms.
The tease of Spring won't last though as the front signals a return to chill as high temperatures will drop back to around 40 on Saturday and in the 40's for next Sunday. While not arctic-like, it's certainly much more typical of February than the 50's we could see for a number of days this week.
In the longer range (into early March), we could see another significant storm system for the end of February (looks like rain this far away but it's still ten days away) and a beginning of a yo-yo temperature regime that is typical of the meteorological transition out of winter and into Spring.
Tom Thunstrom is the editor and publisher of Phillyweather.net. You can follow the site on twitter@phillywx.