A trough that is digging across the Northeast is projected to stall out on Friday across the East Coast, leading to a potentially showery day across the region as the trough "cut off" from the main jet stream in Canada, developing a weak upper level feature across the Mid Atlantic. Modeling has been rather consistent at being inconsistent in handling this upper level feature over the past day or two, with earlier modeling projections showing it would push into the Southeast, shifting to projections that the upper trough would linger nearby for a day or two with shower chances, now shifting again in last night's modeling.
What does this mean for you?
Friday is the clear cut and "easier" day to forecast -- showers will be around the region although placing them geographically may not be a lock. It does appear a wave of rain or showers will fire up along the stalling out front tonight, leading to an unsettled day for the region as showers move through. It appears most of the shower activity should move out of the city by Friday evening (as of now), although we could see some showers lingering through the night.
Saturday does provide a chance for a few showers but it does appear odds are dwindling as the upper level feature moves west. What is a recent change to the models is an earlier introduction to a ridge of high pressure that's projected in both the GFS and Euro to build over the Mid Atlantic, with the core of the upper level high to build over Pennsylvania. This would result in a return to highs in the 90's in the region, perhaps as early as Sunday, with a lower chance of storms. We can't completely rule out thunder from firing up but the odds of this morass of scattered storms continuing would diminish, if the models are right. The heat has been consistently modeled to develop next week -- but the earlier arrival is a recent change.
The unfortunate reality is that modeling has been rather fickle -- as it can be in summer as upper level features are much less pronounced -- with handling the upper level feature. That said, it will get warmer next week and we will be back in the sweat box of heat and humidity...perhaps earlier than what we were thinking. We'll keep you updated.