A strong southwesterly flow of hot, tropically humid air will remain over our area this weekend.
The models have not been doing a stellar job in predicting the placement or timing of showers or thunderstorms that develop in the unstable atmosphere. The thunderstorms over the past week have been developing principally in areas of low level moisture convergence, a parameter difficult to predict in advance.
The pattern will be very hot and humid both Saturday and Sunday. Temperatures in the mid 90s with dew points in the mid 70s will make for oppressively hot conditions.
Regarding thunderstorms, most of the activity is still predicted to occur far north and far west of Philadelphia, but the models show scattered storms developing near PHL late afternoon and evening both Saturday and Sunday. Too difficult to predict in advance– I’ll update Saturday and Sunday mornings as to the best guess for thunderstorm development.
A frontal system will move through our area Friday night into Saturday morning and slowly through NJ on Saturday afternoon. Several days ago, it looked like there might be showers on Saturday in Philadelphia, but right now, it appears that skies will partly sunny during the day. Highs near 90 and humid. Showers possible in PHL during the afternoon, but most likely in NJ, especially eastward, at the shore.
Sunday will be mostly sunny and very warm. High 90. Much less humid.
An unsettled weather pattern is in store for this weekend as a result of surface low pressure moving over our area on Saturday from the west followed by weak low pressure lingering on Sunday. The precipitation will be heavy due to high precipitable water and high dew points and it will be enhanced by an upper air impulse fueling the dynamics.
Saturday will start out with some sunshine, but clouds should move in during the morning, followed by rain and thunderstorms moving in from the west as early as noon to 2 PM. The rain continues into Saturday night and the models are suggesting that the rain could be heavy. It will be very humid and warm. High temps will be about 85.
Sunday might be a bit better, as some sunshine should break out, but scattered showers and thunderstorms still possible. The showers will be scattered, more likely and more areal coverage in the afternoon. Warm and very humid with high temps near 87.
